Support of this research by the National Science Foundation through grants 1254545 and 1437814 is gratefully acknowledged.

NOTE: tBuLi solutions (1.7 M in pentane) and anhydrous tert-butylamine were purchased and used immediately, without purification. In our experience, this protocol works best with freshly-purchased reagents. Standardization of the organolithium reagent may be employed via titration with dibromoethane28, diphenylacetic acid29, or N-pivaloylanilines30, since concentrations of commercial organolithium reagents may vary and the quality of reagents degrades over time. Pentane was purified using a solvent purification system. Solvents were degassed and stored over activated molecular sieves for 24 hr before use.
1. Preparation of Hood Space
NOTE: See Figure 1.
<ol>
	<li>Clear a hood of all clutter.</li>
	<li>Fill a small beaker with a volume of toluene approximately equal to the volume of organolithium reagent to be used (here, 10 ml for the small-scale protocol and 50 ml for the large-scale protocol) and cover with an appropriately-sized watch glass.</li>
	<li>Prepare a beaker of isopropanol with a volume approximately 5 times the amount of organolithium reagent to be used (here, 50 ml for the small-scale and 250 ml for the large-scale) and cover with an appropriately-sized watch glass.</li>
	<li>Prepare a beaker containing dry ice pellets filled up to the volume line approximately 10 times the volume of organolithium reagent to be used (here, 100 ml for the small scale and 500 ml for the large-scale).</li>
	<li>Before proceeding further, inspect the seal/cap of the lithiating agent for corrosive buildup. If the seal is compromised, dispose of the reagent by slowly adding it to 8-10x its volume of dry ice in a beaker.</li>
</ol>
2. Procedure for Small-scale Lithiation in a Hood
NOTE: See Figure 1.
<ol>
	<li>Charge a 25 ml Schlenk flask with a stir bar and neat tBuNH2 (1.8 ml, 17.1 mmol) and fit it with a rubber septum.</li>
	<li>Degas the neat tBuNH2 by opening the Schlenk flask stopcock and turning the Schlenk line to vacuum briefly (~1 sec; tBuNH2 is volatile and will evaporate if held under vacuum). Immediately backfill with inert gas by turning the Schlenk stopcock to inert gas. Repeat twice more. Close the flask stopcock to isolate the flask.</li>
	<li>Prepare an inert gas blanket by attaching three tubes to a glass &#34;T&#34; adapter. Attach one tube to an inert gas source, a second to an oil bubbler, and a third to a Luer-lock needle adapter.</li>
	<li>Purge the blanket apparatus with inert gas for 5 min.</li>
	<li>Slow the flow rate so that a few bubbles per second pass through the oil bubbler.</li>
	<li>Insert the inert gas blanket needle into the septum of the reaction flask and immerse the flask in a dry ice/acetone bath with a magnetic stirrer. Stir gently until the flask has cooled.</li>
	<li>Clamp the tBuLi bottle (25 ml, 1.7 M in pentane) to a ring stand and remove the outer cap. If present, remove any Parafilm and wipe away any grease.</li>
	<li>Select a 20 ml glass syringe and an appropriately-sized plunger. The plunger should slide in easily and should not be able to wiggle or rattle. If a thumb is placed over the syringe tip to seal it, the plunger should not be easily pulled out.</li>
	<li>Fit the 20 ml glass syringe with a long (12 inches), flexible syringe needle. Always be certain to select a syringe with a volume at least double the volume of the reagent to be drawn, and always be sure to attach the needle securely to the syringe.</li>
	<li>Remove the needle adapter for the inert gas blanket from the reaction flask and move it to the tert-butyllithium bottle, piercing the bottle septum to put the reagent bottle under ambient inert gas pressure.
	<ol>
		<li>Alternatively, use a septum-inlet transfer adapter from the reagent vendor as an inert gas blanket. Attach the septum-inlet transfer adapter to the reagent bottle and open the side and top caps. Attach a Schlenk hose to the side arm and purge with inert gas. While purging, replace the top cap with a septum. Leave the Schlenk line stopcock open to the septum-inlet transfer adapter to keep it under positive pressure. 
		NOTE: The commercial vendor suggests the use of a pressurized inert gas source instead of a blanket. This permits the reagent to be &#34;pushed&#34; into the syringe instead of drawn in by pulling the syringe. If the back-pressure setting is not right, over-pressurization can cause the plunger to be pushed out, exposing the reagent to air. Further, back pressure requires the experimenter to apply an equal and opposite pressure on the plunger with the thumb once the desired volume is reached so that the volume in the syringe is held constant. This can cause the reagent to squirt when the needle is pulled from the septum. Thus, the authors prefer the use of an ambient pressure inert gas blanket.</li>
	</ol>
	</li>
	<li>Purge the syringe with inert gas. Open an unoccupied Schlenk hose to inert gas so that there is a gentle flow of inert gas out of the Schlenk hose. Place the needle of the syringe loosely into the end of the hose and draw the plunger in and out several times to purge the interior of the syringe with inert gas.</li>
	<li>With the syringe plunger fully depressed, pierce the bottle septum and immerse the needle in the reagent.</li>
	<li>Gently draw back the plunger until an excess (~11 ml) of reagent has been drawn into the syringe (never invert the reagent bottle). Expel the headspace gas and excess reagent from the syringe by flexing the needle so that the syringe points up and then depressing the plunger until there is no headspace and there is 10.0 ml of reagent in the syringe. At this point, relax the flexion of the syringe needle, turning the syringe right side up.</li>
	<li>With the syringe needle still in the bottle septum, move the inert gas blanket needle adapter back to the reagent flask septum and pierce it.</li>
	<li>Remove the syringe needle from the bottle septum using a free hand (never pull on the syringe to remove the needle, as the needle may pop off). Some flames may be observed upon removal of the needle from the septum. Pierce the rubber septum of the reaction flask with the long syringe needle and suspend it above the stirred tBuNH2.</li>
	<li>Depress the plunger slowly to add all the tBuLi solution dropwise to the stirred tBuNH2.</li>
	<li>Remove the long syringe needle from the septum, leaving the inert gas blanket needle in the reaction flask septum.</li>
	<li>Remove the watch glass from the beaker of toluene and draw a volume of toluene approximately equal to the volume of tBuLi used (~10 ml) into the syringe to dilute the residual tBuLi.</li>
	<li>Remove the watch glass from the isopropanol beaker, place the long needle into the isopropanol, and empty the dilute solution in the syringe into the isopropanol.</li>
	<li>Rinse the syringe several more times with isopropanol to remove residual reagent, after which the syringe is clean.</li>
	<li>Seal the tBuLi reagent bottle septum with some grease to avoid leaks at the puncture sites and place a piece of Parafilm over the greased septum. Replace the outer cap.</li>
	<li>Remove the flask from the ice bath and stir under an ambient inert gas atmosphere until it comes to room temperature.</li>
	<li>Remove the inert gas blanket needle.</li>
	<li>Store the flask at -30 &#176;C overnight. After this time, white powdery solid of [LiNHtBu]8 will be observed.</li>
	<li>Filter the solution, rinse the solid with cold pentane under an inert atmosphere, and dry in vacuo.</li>
</ol>
3. Procedure for Large-scale Lithiation in a Hood
<ol>
	<li>Charge a 100 ml Schlenk flask with a stir bar and neat tBuNH2 (9 ml, 85.5 mmol) and fit it with an addition funnel that holds at least 50 ml. Clip the addition funnel to the flask using a keck clamp. Cap the top of the addition funnel with a rubber septum. Close the addition funnel&#39;s stopcock.</li>
	<li>Degas the neat tBuNH2 by opening the Schlenk flask stopcock and turning the Schlenk line to vacuum briefly (~1 sec; tBuNH2 is volatile and will evaporate if held under vacuum). Immediately backfill with inert gas by turning the Schlenk stopcock to inert gas. Repeat twice more. Close the flask stopcock to isolate the flask and the addition funnel.</li>
	<li>Prepare an inert gas blanket by attaching three tubes to a glass &#34;T&#34; adapter. Attach one tube to an inert gas source, a second to an oil bubbler, and a third to a Luer-lock needle adapter.</li>
	<li>Purge the blanket apparatus with inert gas for 5 min.</li>
	<li>Slow the flow rate so that a few bubbles per sec pass through the oil bubbler.</li>
	<li>Clamp the tBuLi bottle to a ring stand and remove the outer cap. Remove any Parafilm and wipe away any grease.</li>
	<li>Transfer the inert gas blanket to the septum of the addition funnel. Lower the flask into a dry ice bath to cool.</li>
	<li>Using another inert gas line, apply a gentle flow of inert gas to the tBuLi bottle.</li>
	<li>Insert one end of a cannula into the tBuLi bottle and suspend it above the solution.</li>
	<li>Insert the other end into the addition funnel so that the tip is below the pressure equalizing side-arm.</li>
	<li>Lower the end of the cannula above the tBuLi into the liquid and control the speed of addition via the inert gas line. Fill the addition funnel to the 50 ml line.</li>
	<li>When the addition is complete, remove the cannula end from the lithiating reagent solution and leave it suspended above the tBuLi reagent.</li>
	<li>Remove the opposite end of the cannula from the addition funnel.</li>
	<li>Remove the end of the cannula in the tBuLi bottle. Then, remove the inert gas line from the tBuLi bottle.</li>
	<li>Turn the stopcock on the addition funnel to add the tBuLi dropwise to the stirring tBuNH2.</li>
	<li>Seal the tBuLi reagent bottle septum with some grease to avoid leaks at the puncture sites and place a piece of Parafilm over the greased septum. Replace the outer cap.</li>
	<li>Remove the addition funnel from the Schlenk flask using the following steps:
	<ol>
		<li>Place the Schlenk flask under positive pressure of inert gas by opening the Schlenk flask stop cock and the Schlenk line stop cock. Remove the keck clamp and the addition funnel from the Schlenk flask. The flask will be protected by a flow of inert gas out of the flask, but the addition funnel may smoke or flame briefly upon exposure to air.</li>
		<li>Wipe away the grease on the inner neck of the Schlenk flask using a paper towel wetted with hexanes and repeat until the ground glass of the flask appears dry. Stopper the flask with a rubber septum.</li>
		<li>Place the inert gas blanket needle into the Schlenk flask septum.</li>
	</ol>
	</li>
	<li>Remove the flask from the ice bath and stir under an ambient inert gas atmosphere until it comes to room temperature.</li>
	<li>Remove the inert gas blanket needle.</li>
	<li>Store the flask at -30 &#176;C overnight. After this time, white powdery solid of [LiNHtBu]8 will be observed.</li>
	<li>Filter the solution, rinse the solid with cold pentane under an inert atmosphere, and dry in vacuo.</li>
</ol>
4. Procedure for Lithiation in a Glovebox
<ol>
	<li>Bring all reagents, a reaction flask, a stir bar, a stopper, and a greased desiccator (or another sealable container to be used for waste) into the glovebox via the antechamber.</li>
	<li>Charge a flask with a stir bar and degassed neat tBuNH2 (1.8 ml, 17.1 mmol). Cover the flask with a glass stopper or septum to prevent evaporation of volatile tert-butyl amine.</li>
	<li>Clamp the tBuLi bottle (25 ml, 1.7 M in pentane) to a ring stand and remove the outer cap. Optional: Remove the septum cap using a bottle opener, with the bottle firmly clamped in place. Once the bottle cap is removed, do not remove the bottle from the glovebox until empty. If removed, carefully quench the remaining tBuLi in a hood with an appropriate quenching reagent such as dry ice or isopropanol.</li>
	<li>Prepare a small vial of ~10 ml toluene to wash the syringe after the addition.</li>
	<li>Fit a 20 ml syringe with a needle. Always be certain to select a syringe with a volume at least double the volume of the reagent to be drawn, and always be sure to attach the needle securely to the syringe.</li>
	<li>Insert the needle into the tBuLi reagent and gently draw the plunger back until an excess (~11 ml) of reagent has been drawn into the syringe. Then, invert the syringe, pointing the needle up.</li>
	<li>Hold a paper towel near the needle and gently depress the plunger to remove the headspace gas until a microdroplet of reagent emerges from the end of the needle. Remove excess reagent from the syringe by placing the needle into the reagent bottle and depressing the plunger until 10.0 ml of reagent remains in the syringe. If any reagent solution spills, wipe it up with a paper towel or Kimwipe and place the waste into the waste desiccator.</li>
	<li>Remove the stopper or septum from the reaction flask and slowly add the tBuLi to the stirred tBuNH2. Since the reaction is performed without a cold bath, take care to avoid adding the reagent too quickly, as the exotherm can cause boiling. Stopper the reaction flask.</li>
	<li>Draw toluene from the toluene vial into the syringe to dilute the residual reagent, and place the syringe, needle, and any paper towel waste into the desiccator. Seal the desiccator.</li>
	<li>Re-cap and store the tBuLi reagent bottle, preferably in a glovebox freezer to improve longevity.</li>
	<li>Remove the sealed desiccator containing the used glassware, the syringe with toluene, and any paper towels from the glovebox, and immediately place it into a hood.</li>
	<li>Open the desiccator and empty the syringe containing dilute tBuLi into a beaker of isopropanol to quench the reagent. Rinse the syringe several more times with isopropanol.</li>
	<li>Store the reaction flask at -30 &#176;C overnight, after which time white powdery solid of [LiNHtBu]8 are observed.</li>
	<li>Filter the solution, rinse the solid with cold pentane under an inert atmosphere, and dry in vacuo.</li>
</ol>
5. How to Abort the Reaction or in Case of Fire
NOTE: See Figure 1.
<ol>
	<li>If at any point the reaction needs to be aborted, slowly empty any unused organolithium reagent in the syringe into the dry ice. Flames may occur as the reagent is emptied, but the dry ice should quench them.</li>
	<li>If at any point the toluene or isopropanol catches fire, simply place the watch glass onto the beaker so that the flames will be smothered.</li>
	<li>If a circumstance ever occurs where a fire cannot be quenched by this method, immediately use the fire extinguisher.</li>
	<li>In the unlikely event that hair or clothing catches fire, immediately use the safety shower.</li>
</ol>

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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+convenient+method+for+estimation+of+alkyllithium+concentrations.">A convenient method for estimation of alkyllithium concentrations.</a> J Org Chem. 41 (10), 1879-1880 (1976).</li><li>Suffert, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+direct+titration+of+organolithium+reagents+using+N-pivaloyl-o-toluidine+and/or+N-pivaloyl-o-benzylaniline.">Simple direct titration of organolithium reagents using N-pivaloyl-o-toluidine and/or N-pivaloyl-o-benzylaniline.</a> J Org Chem. 54 (2), 509-510 (1989).</li><li>Barnett, N. D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+octameric+structure+of+the+lithium+primary+amide+[{ButN(H)Li}8]+and+its+implication+for+the+directed+synthesis+of+heterometallic+imide+cages.">Novel octameric structure of the lithium primary amide [{ButN(H)Li}8] and its implication for the directed synthesis of heterometallic imide cages.</a> Chem Comm. 32 (20), 2321-2322 (1996).</li><li>Sigma-Aldrich. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Technical Bulletin AL-134: Handling Air-Sensitive Reagents. , (2012).</li></ol>

The authors have nothing to disclose.

For this lithiation experiment, tert-butyl lithium amide (LiNHtBu) is synthesized via lithiation of tert-butyl amine (tBuNH2) using tert-butyl lithium (tBuLi), forming isobutane as a side product. The described protocol is a modification of a previously-reported protocol31 and proceeds according to the following reaction:
tBuNH2 + tBuLi&#160; &#8594;&#160; tBuH + 1/8 [LiNHtBu]8. &#160; &#160;&#160; (2)
The original report for the synthesis of LiNHtBu differs from this protocol in that it employed the use of less reactive n-butyl lithium as the organolithium reagent. In general, one should always choose the less reactive organolithium reagent whenever possible. However, for the purpose of this paper, the authors have elected to demonstrate the safe usage of the more reactive tert-butyl lithium solution so that viewers can observe the proper handling of the most challenging reagent. This protocol may be easily applied to the use of the less reactive organolithium reagents.
Critical Steps 
Due to the highly pyrophoric nature of organolithium reagents, all operations must be carried out under inert atmosphere conditions, necessitating the use of a Schlenk or inert gas line, or an inert atmosphere glovebox. While operation in a glovebox is a far simpler approach, it is associated with its own risks, different from those of performing lithiations on an inert gas line. Either of these approaches therefore requires great care and adherence to protocol. Described here are two protocols for lithiation: one on an inert gas (Schlenk) line, and one within a glovebox. When performing a lithiation on an inert gas line, a familiarity with the operation of air-free glassware and protocols is invaluable. However, since different laboratories may adopt slightly different practices, a step-by-step protocol for each method is thoroughly described. The chemical vendor offers its own recommended glassware apparatus and protocol for proper use of air-sensitive reagents32. The Protocol section outlines a procedure similar to the vendor&#39;s, but which has been modified to maximize safety and ease, specifically for alkyllithium protocols. The detailed procedure is available in the Protocol section, but here, some important points are highlighted to maximize safety and success.
NOTE: Never work in the laboratory alone. 
PPE 
An extremely important consideration is the use of proper personal protective equipment (PPE), which for lithiation includes a proper-fitting lab coat, safety glasses, long pants (preferably made of non-flammable material), closed-toed shoes, and a hair tie (if applicable). While best practices can ensure that no fires occur in most cases, tert-butyl lithium is extremely pyrophoric, and accidents can happen. When they do, the safety of the researcher is better secured if they are shielded by the proper PPE. The UCLA alumna&#39;s most significant mistakes were that she performed a lithiation with no laboratory coat and that she was wearing clothing made of flammable material20.
Ventilation 
Lithiations outside the glovebox should always be performed in a hood. If a clear hood is not available, do not perform a lithiation until a clear, uncluttered hood space free of other flammable chemicals is secured. The sash should be lowered as much and as often as possible. An additional mistake of the UCLA alumna was that there were other flammables in the hood (hexanes), which spilled and caught fire, igniting her clothes20.
Inert Gas 
A lithiation requires the use of inert gas. A Schlenk line (double manifold switchable between inert gas and vacuum) is ideal, though any inert gas source with good flow control will work.
Syringe 
Glass syringes are preferable to plastic syringes due to their chemical inertness and smoother plunger motion. A long (1-2 ft)32, flexible needle must always be attached securely to the delivery syringe. Another of the UCLA alumna&#39;s mistakes was the use of a too-short (1.5 inches)20 needle, which may have necessitated inverting the reagent bottle to draw the reagent into the syringe, which can lead to spills and fire. Thus, a long needle should always be used so that the bottle does not need to be inverted. The needle should be attached securely so that it does not pop off during reagent delivery. Luer-lock style syringes (Figure 2) are best. If using a push-on &#34;slip-tip&#34; syringe needle system, ensure that the needle is extremely well attached before proceeding. A syringe should always be selected that is at least twice the volume of the desired quantity of organolithium reagent32. This is due to the fact that head space always occupies some volume of the syringe while drawing a reagent. Another of the UCLA alumna&#39;s mistakes was the use of a syringe that was too small. When the syringe reached capacity, it likely popped open, splashing tBuLi onto her unprotected arm20.
Quenching Agents 
A small beaker containing toluene (volume approximately equal to the volume of organolithium reagent to be delivered) should be located in the hood within reach of &#8211; but not right next to &#8211; the reaction vessel. A watch glass appropriately sized to cover this beaker in case of fire should also be placed over the beaker. This beaker will be used to dilute the residual reagent contaminating the syringe after the reagent addition (Figure 1).
A second beaker containing isopropanol (volume approximately five times the volume of organolithium reagent to be delivered) should also be located in the hood within reach of &#8211; but not right next to &#8211; the reaction vessel. A second watch glass appropriately sized to cover this beaker in case of fire should also be placed on top of the beaker. This vessel is used to quench the residue left in the syringe after the addition (Figure 1).
Third, a beaker of dry ice (approximately ten times the volume of organolithium reagent to be delivered) should be located in reach of the reaction vessel. In the event of the syringe needle coming loose, or something else going wrong, this dry ice may be used to quench the remaining organolithium reagent in the syringe (Figure 1).
Finally, a fire extinguisher should be located nearby in case of emergency, and the location and proper operation of the safety shower should be noted.
The Reagent Bottle 
Outside the glovebox, use only organolithium reagent bottles with septum-sealed bottle caps (Figure 3). The purchase of small bottles is recommended since 1) organolithium reagents degrade over time, and long-term storage is not recommended, 2) septa can degrade over time, exposing the reagent to air, and 3) small volumes of pyrophorics are less dangerous than large volumes. The organolithium reagent bottle should be set on the bench and clamped to a ring stand before use (Figure 1).
The Reaction Vessel 
The reaction vessel should be oven- or flame-dried and cooled to room temperature under an inert atmosphere to ensure that no traces of water exist on the sides of the glass. The vessel containing the reagent to which the organolithium solution will be added should be clamped above a stir plate and degassed to remove air. This may be done either by purging the vessel with inert gas or by performing several evacuation-inert gas fill cycles on a Schlenk line. Alternatively, the flask can be charged with reagents and solvent in an inert atmosphere glovebox and sealed before removal from the glovebox. The degassed flask should be fitted with a septum and protected by an inert gas blanket (see Protocol and Figure 1). If the synthetic protocol permits, the flask should also be immersed into a cold bath such as dry ice/acetone to control the exotherm that will result when the organolithium reagent is added.
Notes on Lithiation in an Inert-atmosphere Glovebox 
The use of air-free gloveboxes makes the handling of air-sensitive reagents vastly simpler, but it comes with its own risks. Since organolithium reagents are shielded from air in the glovebox, it is easier to become complacent and careless. While handling the reagents is simpler, a spill within the glovebox creates a dilemma: the spilled reagent must be wiped up with paper towels, but then the pyrophoric reagent and flammable cloth must be removed from the box and placed back into air, at which point, they will immediately catch fire. To avoid these hazards, reagents and reaction flasks should always be clamped securely within the glovebox, and open bottles and flasks should never be moved or handled by hand. Any materials containing residual reagent should be removed from the glovebox in a sealed desiccator (or similar container) and moved to a hood before being opened and exposed to air.
Know the Location and Operation of Emergency Equipment 
Know the location and operation of the lab&#39;s fire extinguisher, so that in the event of a fire that cannot be put out by smothering with a watch glass, one can react quickly and decisively. Know also the location and operation of the laboratory&#39;s safety shower. In the unlikely event that a piece of clothing catches fire, immediately use the safety shower. If someone else&#39;s clothes catch fire, immediately direct them to the safety shower. If the laboratory does not have both a safety shower and a fire extinguisher, do not attempt a lithiation reaction. What may have been the final opportunity to save the life of the UCLA alumna was missed when neither she nor the postdoc working with her used the safety shower or an extinguisher to extinguish the flames. Rather, her postdoctoral coworker attempted to pat out the flames with a lab coat, which also caught fire. Ultimately, she sat on the floor while her postdoctoral coworker attempted to put out the flames by pouring beakers of water, filled from the sink, on the flames20.
Organolithium reagents are excellent for the deprotonation of weakly-acidic hydrogens or for acting as a source of alkyl groups, and they are more aggressive and reactive than the more standard Grignard reagents. Limitations of this technique can include kinetically sluggish reactions, in which case modification of the protocol can aid the chemical transformation19. Additionally, the high reactivity of organolithiums can interfere with desired chemistry. For instance, carbanions are generally excellent nucleophiles. Attempted deprotonation of an electrophilic substrate (such as a carboxylic acid) is likely to lead to nucleophilic attack instead of deprotonation. Thus, chemical knowledge and intuition is required when selecting reagents of this (or any) sort. Lithiation reactions will continue to play a role in synthetic organic and inorganic chemistry for the foreseeable future, and thus, an understanding of safe use is essential. Lithiation reactions are accomplished safely every day, and there is no cause to fear performing this reaction chemistry. However, the reagents deserve a measure of respect and care. It is essential that the multiple required fail-safes be followed to avoid the possibility of injury. In this protocol, a step-by-step procedure for a safe lithiation reaction is demonstrated and published as an open access article so that any researcher in the world can use it as training, free of charge. As such, the authors hope that this report may make the lithiation protocol accessible to a wide array of groups and prevent future tragedies.

reattivi di organo-litio (RLI) sono basi potenti che sfruttano i legami non polari, forti di idrocarburi per generare basi coniugate che possono deprotonate quasi qualsiasi composto di acidità anche moderata. Essi servono come alternative più aggressivi ad ammidi litio (ad esempio, LDA) e reagenti di Grignard. La loro incredibilmente forte basicità li rende di grande utilità nella sintesi organiche e inorganiche, e la loro ampia applicabilità è stata accuratamente descritta in diverse recensioni recenti 1-3. reattivi di organo-litio possono facilmente deprotonate acidi estremamente deboli quali alcoli, ammine, e idrocarburi sia benzilici e alifatici. La reazione è guidato dalla formazione di una stalla forte, legame, alchile CH. Li + R - + HX → LiX + RH (1) Concetti generali circostanti reattivi di organo-litio sono stati esaminati 4-7, ma noiqui evidenziare l&#39;utilità di questi reagenti di sfruttare la diversa pK a valori di più idrocarburi differenti per selezionare una base coniugata con appropriata alimentazione deprotonating. Per esempio, poiché l&#39;acidità di idrocarburi alifatici diminuisce con livelli crescenti di sostituzione (ad esempio, 1 °&gt; 2 °&gt; 3 °), terz -butyllithium è il reagente alkyllithium più aggressivo, mentre metillitio è il più delicato. Fenillitio è notevolmente più mite rispetto metillitio a causa della capacità del fenilico di delocalizzare la carica dell&#39;anione fenile deprotonato. Così, i reattivi di organo-litio più comunemente usati sono, in ordine crescente di basicità: PHLI &lt;Meli &lt;BuLi &lt;s -BuLi &lt;t BuLi. Mentre precisi valori di pK a delle alcani protonati sono difficili da misurare a causa della loro mancanza di acidità, pK approximate un valori sono forniti nella tabella 1 7-10 unlungo con altri reagenti protici incontrate comunemente deprotonato da reattivi di organo-litio in chimica sintetica. Tabella 1 prevede, in sintesi, uno strumento visivo per prevedere quali basi possono essere usati per deprotonate che acidi. Al di là di chimica acido-base, i reagenti alkyllithium sono state sfruttate in chimica inorganica e organometallica come mezzo per fornire leganti a base di carbonio 11,12, reagenti transmetallate nella catalisi 13-15, o facilitare la reattività organometallica da fotolito legame M-Me omolisi 16, 17. Mentre reagenti alkyllithium sono termodinamicamente basi molto forti, la loro reattività può essere lenta in alcune reazioni, che richiede l&#39;ottimizzazione delle condizioni di reazione 18. Generalmente, il loro comportamento cinetico può essere migliorata mediante sostituzione dello ione litio acido Lewis con un acido debole Lewis come il potassio, come si vede nella generazione di &quot;base di Schlosser&quot; di BuLi e tert potassio </em&gt; -butoxide 19. Mentre l&#39;utilità dei reattivi di organo-litio in sintesi è innegabile, l&#39;uso di questi reagenti richiede precauzioni appropriate. I reagenti sono piroforico, reagire violentemente in aria o con acqua e con una reazione esotermica vigorosa. Essi generano organiche volatili che spesso accendono a causa delle alte temperature di decomposizione. Così, gli incendi possono verificarsi durante lithiations, in particolare quando accurate procedure operative standard non vengono seguite. Più infame è il caso di un allieva di laurea di recente laureato della University of California, Los Angeles (UCLA), che lavora come assistente di ricerca. Come risultato di un tragico incidente durante una reazione litiazione con il reagente organolitio più reattiva, litio terz butil, lo studente ricevuto ustioni fatali quando una siringa piena di soluzione venne a parte e acceso i vestiti 20. Tra gli errori commessi erano l&#39;uso di una siringa impropriamente dimensioni unND ago, la mancanza di dispositivi di protezione adeguati (DPI), e un fallimento per usare la doccia di sicurezza disponibili 20. La natura sensibile dei reagenti carbanion comuni ha ispirato lo sviluppo di alternative più sicure in solventi ad alta polarità 21, come eutettiche miscele di solventi 22-24, e per i reagenti di Grignard, anche l&#39;acqua 25-27. Tuttavia, la versatilità di reattivi di organo-litio li rende di continuo programma di utilità per il prossimo futuro. L&#39;obiettivo di questo protocollo e sperimentare visualizzato è quello di dimostrare un approccio approfondito e attento a litiazione, accessibile a qualsiasi studente di chimica ben addestrato, che ha bisogno di reattivi di organo-litio. La nostra speranza è che questo protocollo di accesso aperto illustrerà che cosa fare (e cosa non fare) per ottenere un litiazione di successo e sicuro, che altri laboratori possono utilizzare questa pubblicazione come una risorsa di formazione, e che attraverso questo approfondita, demonstrati visivasu, futuri incidenti possono essere evitati. Qui, un protocollo sicuro per litiazione utilizzando litio tert-butil più reattiva viene descritta, che può essere adattato per l&#39;uso con i reagenti organolitio meno reattivi.

<table border="0" cellpadding="0" cellspacing="0" width="610">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Schlenk Flask, 25 mL</td>
			<td style="width:111px;">Chemglass</td>
			<td style="width:119px;">AF-0520-02</td>
			<td style="width:167px;">25mL Flask, Reaction, 14/20 outer joint, 2mm glass stpk, Airfree, Schlenk</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Rubber Septum</td>
			<td style="width:111px;">Chemglass</td>
			<td style="width:119px;">CG-3024-01</td>
			<td>Septum stopper, suba-seal, For 14/20-14/35 outer joints and 12.5mm ID tubing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Stir Bar</td>
			<td style="width:111px;">Fisher Scientific</td>
			<td style="width:119px;">14-512-130</td>
			<td>Various sized stir bars</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">tert-butyllithium</td>
			<td style="width:111px;">Sigma-Aldrich</td>
			<td style="width:119px;">186198-4X25ML</td>
			<td>1.7M t-butyllithium in pentane, 4 x 25mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">tert-butylamine</td>
			<td style="width:111px;">Sigma-Aldrich</td>
			<td style="width:119px;">391433-100ML</td>
			<td>tert-butylamine, purified by redistillation, &#62;99.5%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">hexanes</td>
			<td style="width:111px;">Fisher Scientific</td>
			<td style="width:119px;">H292-4</td>
			<td>4L, certified ACS, hexanes, &#62;98.5%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">isopropanol</td>
			<td style="width:111px;">Fisher Scientific</td>
			<td style="width:119px;">A416-4</td>
			<td>4L, 2-propanol, certified ACS plus, &#62;99.5%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Dry ice</td>
			<td style="width:111px;">Airgas</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">Pure Solv Solvent Purification System</td>
			<td style="width:111px;">Inert Technology</td>
			<td style="width:119px;">MD-5</td>
			<td>Alumina collumns through which fresh, degassed solvents are passed to remove water.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:215px;">Aldrich Sure/Seal septum-inlet transfer adapter</td>
			<td style="width:111px;">Sigma-Aldrich</td>
			<td style="width:119px;">Z407186</td>
			<td>Adapter for removal of air-sensitive reagents under nitrogen blanket</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">&#160;Keck Standard Taper Clips</td>
			<td style="width:111px;">Chemglass</td>
			<td>CG-145-03</td>
			<td>clamp for securing glassware connections</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:215px;">Addition Funnel</td>
			<td style="width:111px;">Kontes</td>
			<td style="width:119px;">K634000-0060</td>
			<td>Funnel for dropwise addition of reagent to flask</td>
		</tr>
	</tbody>
</table>

a protocol for safe lithiation reactions using organolithium reagents

reattivi di organo-litio sono potenti strumenti nella cassetta degli attrezzi del chimico sintetico. Tuttavia, la natura estrema piroforico dei reagenti più reattivi garantisce la tecnica corretta, una formazione approfondita e corretta dispositivi di protezione individuale. Per aiutare nella formazione dei ricercatori svolta reattivi di organo-litio, un approfondito, step-by-step di protocollo per l&#39;uso sicuro ed efficace di terz -butyllithium su una linea di gas inerte o all&#39;interno di un cassetto portaoggetti è descritto. Come reazione di modello, preparazione di litio tert-butil amide dalla reazione di tert-butil ammina con un equivalente di litio tert-butil è presentato.

The typical yield of this reaction is ~670 mg (8.5 mmol, ~50%). Additional crops of crystals may be obtained by concentrating the filtrate and chilling the solution. However, purity is often compromised by additional crops. When this protocol is followed carefully by a prepared and practiced researcher, it generally proceeds without incident. In our experience, in the rare cases when the reaction must be aborted or a fire occurs, the availability of watch glass covers, dry ice, and isopropanol quench beakers, and the localization of the operation in a hood provide sufficient contingency.
Confirmation of the product by NMR (Figure 4) or X-ray diffraction is necessary, as the use of impure or water-contaminated reagents frequently leads to failure to obtain the desired product. The 1H NMR spectrum shows two peaks, as expected, in a ratio of 1:9 (representing, respectively, the single amide proton and the nine tert-butyl protons). Indexing of a crystal grown from pentane or hexane is consistent with the reported crystal structure of the product31. NMR (400 MHz, benzene-d6) &#948; -1.53 (s, 1H, NH), 1.37 (s, 9H, But). Unit cell: P2/n, a = 12.05(2), b = 12.62(2), c = 18.24(3) &#197;, &#946; = 105.52(5)&#176;, V = 2672(14) &#197;3.
<img alt="Figure 1" src="/files/ftp_upload/54705/54705fig1.jpg" /> 
Figure 1: Apparatus Diagram. The appearance of the interior of a hood for reaction outside the glovebox is shown. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54705/54705fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54705/54705fig2.jpg" /> 
Figure 2: The Syringe with Needle. A 10 ml syringe with a needle attached using a Luer-lock tip is shown. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54705/54705fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/54705/54705fig3.jpg" /> 
Figure 3: Septum-sealed Bottle Cap. The reagent is sold by the vendor with a sealed metal bottle cap with a rubber septum that may be pierced with a needle. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54705/54705fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" src="/files/ftp_upload/54705/54705fig4.jpg" /> 
Figure 4: 400 MHz 1H NMR Spectrum of LiNHtBu in C6D6. The NMR spectrum of the product shows the expected two signals for the amide and tert-butyl protons, with an integral ratio of 1:9, respectively. Residual protiosolvent signal is labelled with *. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54705/54705fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table fo:keep-together.within-page="1">
	<tbody>
		<tr>
			<td>Acid</td>
			<td>pKa</td>
			<td>Base</td>
		</tr>
		<tr>
			<td>i-butane7</td>
			<td>&#62;51</td>
			<td>tBuLi</td>
		</tr>
		<tr>
			<td>n-butane (2o carbon) 7</td>
			<td>~50</td>
			<td>s-BuLi</td>
		</tr>
		<tr>
			<td>n-butane (1o carbon) 7</td>
			<td>~50</td>
			<td>BuLi</td>
		</tr>
		<tr>
			<td>methane7</td>
			<td>48</td>
			<td>MeLi</td>
		</tr>
		<tr>
			<td>benzene7</td>
			<td>43</td>
			<td>PhLi</td>
		</tr>
		<tr>
			<td>toluene7</td>
			<td>40</td>
			<td>TolLi</td>
		</tr>
		<tr>
			<td>R2NH8</td>
			<td>36</td>
			<td>RNHLi</td>
		</tr>
		<tr>
			<td>ArNH29</td>
			<td>31</td>
			<td>ArNHLi</td>
		</tr>
		<tr>
			<td>ROH9</td>
			<td>15</td>
			<td>ROLi</td>
		</tr>
		<tr>
			<td>ArOH8,9</td>
			<td>10</td>
			<td>ArOLi</td>
		</tr>
	</tbody>
</table>
Table 1: pKa values of Hydrocarbons and Their Corresponding Lithiated Conjugate Bases.

Watch this Scientific Journal Video about A Protocol for Safe Lithiation Reactions Using Organolithium Reagents at JoVE.com

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

The safe and proper use of organolithium reagents is described.

Un protocollo per reazioni sicuro litiazione Utilizzando organolitio Reagenti

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents ...

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Nanyang Technological University

Research

JoVE Journal

Chemistry

30.7K Views.  Temple University. The safe and proper use of organolithium reagents is described.

Video: A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Unsymmetrical 1,2-diols are hardly accessible by reductive pinacol coupling processes. A successful execution of such a transformation is bound to a clear recognition and strict differentiation of two similar carbonyl compounds (aldehydes &#8594; secondary 1,2-diols or ketones &#8594; tertiary 1,2-diols). This fine-tuning is still a challenge and an unsolved problem for an organic chemist. There exist several reports on successful execution of this transformation but they cannot be generalized. Herein we describe a catalytic direct pinacol coupling process which proceeds via a retropinacol/cross-pinacol coupling sequence. Thus, unsymmetrical substituted 1,2-diols can be accessed with almost quantitative yields by means of an&#160;operationally simple performance under very mild conditions. Artificial techniques, such as syringe-pump techniques or delayed additions of reactants are not necessary. The procedure we describe provides a very rapid access to cross-pinacol products (1,2-diols, vicinal diols). A further extension of this new process, e.g. an enantioselective performance could provide a very useful tool for the synthesis of unsymmetrical chiral 1,2-diols.

A novel account for the synthesis of unsymmetrical 1,2-diols based on a retropinacol/cross-pinacol coupling mechanism is described. Due to the catalytic execution of this reaction a considerable improvement compared to conventional cross-pinacol couplings is achieved.

Retropinacol / Cross-Pinacol Coupling Reazioni - Una catalitico Accesso al 1,2-asimmetriche Dioli

Unsymmetrical 1,2-diols are hardly accessible by reductive pinacol coupling processes. A successful execution of such a transformation is bound to a clear ...

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Chimica

A Simple and Rapid Protocol for Measuring Neutral Lipids in Algal Cells Using Fluorescence

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay.

A simple protocol to determine the neutral lipid content of algal cells using a Nile Red staining procedure is described. This time-saving technique offers an alternative to traditional gravimetric-based lipid quantification protocols. It has been designed for the specific application of monitoring bioprocess performance.

Una semplice e rapida il protocollo per la misurazione lipidi neutri in cellule algali Uso fluorescenza

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal ...

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible to ensure consistent product quality over time using this technique. We here show how to interface a commercially available flow unit with a Raman spectrometer. The Raman flow cell is placed after the back-pressure regulator, meaning that it can be operated at atmospheric pressure. In addition, the fact that the product stream passes through a length of tubing before entering the flow cell means that the material is at RT. It is important that the spectra are acquired under isothermal conditions since Raman signal intensity is temperature dependent. Having assembled the apparatus, we then show how to monitor a chemical reaction, the piperidine-catalyzed synthesis of 3-acetylcoumarin from salicylaldehyde and ethyl acetoacetate being used as an example. The reaction can be performed over a range of flow rates and temperatures, the in-situ monitoring tool being used to optimize conditions simply and easily.

Real-time monitoring allows for fast optimization of reactions performed using continuous-flow processing. Here the preparation of 3-acetylcoumarin is used as an example. The apparatus for performing in-situ Raman monitoring is described, as are the steps required to optimize the reaction.

Monitoraggio in tempo reale delle reazioni eseguita utilizzando la lavorazione a flusso continuo: La preparazione di 3-Acetylcoumarin come un esempio

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible ...

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important structural element found in many complex natural products and pharmaceuticals. Owing to the continual discovery of new guanidine-containing natural products and designed small molecules, rapid and efficient guanidinylation methods are of keen interest to synthetic and medicinal organic chemists. Because the nucleophilicity and basicity of guanidines can affect subsequent chemical transformations, traditional, indirect guanidinylation is typically pursued. Indirect methods commonly employ multiple protection steps involving a latent amine precursor, such as an azide, phthalimide, or carbamate. By circumventing these circuitous methods and employing a direct guanidinylation reaction early in the synthetic sequence, it was possible to forge the linear terminal guanidine containing backbone of clavatadine A to realize a short and streamlined synthesis of this potent factor XIa inhibitor. In practice, guanidine hydrochloride is elaborated with a carefully constructed protecting array that is optimized to survive the synthetic steps to come. In the preparation of clavatadine A, direct guanidinylation of a commercially available diamine eliminated two unnecessary steps from its synthesis. Coupled with the wide variety of known guanidine protecting groups, direct guanidinylation evinces a succinct and efficient practicality inherent to methods that find a home in a synthetic chemist&#39;s toolbox.

Here, we present a protocol for direct, early stage guanidinylation that enables rapid total synthesis of aminoguanidine-containing small organic molecules. An advanced synthetic intermediate used in the synthesis of a blood coagulation factor XIa inhibitor was prepared using this protocol.

Un diretto, Early Stage Guanidinylation protocollo per la sintesi di complessi Aminoguanidine contenenti prodotti naturali

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important ...

A Protocol for the Production of Gliadin-cyanoacrylate Nanoparticles for Hydrophilic Coating

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules. Alkyl cyanoacrylate is a monomer that instantly polymerizes at RT when it is applied to the surface of materials. Its polymerization reaction is initiated by the trace amounts of weakly basic or nucleophilic species on the surface, including moisture. Once polymerized, the polymerized alkyl cyanoacrylates show a strong affinity with the object materials because nitrile groups are in the backbone of poly (alkyl cyanoacrylate). Proteins also work as initiator for this polymerization because they contain amine groups that can initiate the polymerization of cyanoacrylate. If aggregated protein is used as an initiator, protein aggregate is surrounded by the hydrophobic poly(alkyl cyanoacrylate) chains after the polymerization reaction of alkyl cyanoacrylate. By controlling the experimental condition, particles in the nanometer range are produced. The produced nanoparticles readily adsorb to the surface of most materials including glass, metals, plastics, wood, leather, and fabrics. When the surface of a material is sprayed with the produced nanoparticle suspension and rinsed with water, the micellar structure of nanoparticle changes its conformation, and the hydrophilic proteins are exposed to the air. As a result, the nanoparticle-coated surface changes to hydrophilic.

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic. The produced nanoparticle is an assembly of gliadin-cyanoacrylate diblock copolymers. Spray coating with the produced nanoparticle changes the surface of target material to a hydrophilic surface.

Un protocollo per la produzione di nanoparticelle gliadina-cianoacrilato per rivestimento idrofilo

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray ...

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic nature of the monomer is conserved. The resulting polymer, polynorbornene, has a very high glass transition temperature, Tg, and interesting optical and electrical properties. However, the polymerization of functional norbornenes by this mechanism is complicated by the fact that the endo substituted norbornene monomer has, in general, a very low reactivity. Furthermore, the separation of the endo substituted monomer from the exo monomer is a tedious task. Here, we present a simple protocol for the polymerization of substituted norbornenes (endo:exo ca. 80:20) bearing either a carboxylic acid or a pendant double bond. The process does not require that both isomers be separated, and proceeds with low catalyst loadings (0.01 to 0.02 mol%). The polymer bearing pendant double bonds can be further transformed in high yield, to afford a polymer bearing pendant epoxy groups. These simple procedures can be applied to prepare polynorbornenes with a variety of functional groups, such as esters, alcohols, imides, double bonds, carboxylic acids, bromo-alkyls, aldehydes and anhydrides.

We describe the catalytic insertion polymerization of 5-norbornene-2-carboxylic acid and 5-vinyl-2-norbornene to form functional polymers with a very high glass transition temperature.

Un protocollo semplice ed efficiente per l&#39;inserimento catalitica polimerizzazione di norborneni funzionali

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Un protocollo ottimizzato per la radiomarcatura efficiente di oro nanoparticelle utilizzando un<sup&gt; 125</sup&gt; Azide gruppo I-etichettati protesico

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

The MPLEx Protocol for Multi-omic Analyses of Soil Samples

Mass spectrometry (MS)-based integrated metaproteomic, metabolomic, and lipidomic (multi-omic) studies are transforming our ability to understand and characterize microbial communities in environmental and biological systems. These measurements are even enabling enhanced analyses of complex soil microbial communities, which are the most complex microbial systems known to date. Multi-omic analyses, however, do have sample preparation challenges, since separate extractions are typically needed for each omic study, thereby greatly amplifying the preparation time and amount of sample required. To address this limitation, a 3-in-1 method for the simultaneous extraction of metabolites, proteins, and lipids (MPLEx) from the same soil sample was created by adapting a solvent-based approach. This MPLEx protocol has proven to be both simple and robust for many sample types, even when utilized for limited quantities of complex soil samples. The MPLEx method also greatly enabled the rapid multi-omic measurements needed to gain a better understanding of the members of each microbial community, while evaluating the changes taking place upon biological and environmental perturbations.

A protocol is presented for simultaneously extracting metabolites, proteins, and lipids from a single soil sample, allowing reduced sample preparation times and enabling multi-omic mass spectrometry analyses of samples with limited quantities.

Il protocollo MPLEx Multi-omic nell'analisi di campioni di terreno

Mass spectrometry (MS)-based integrated metaproteomic, metabolomic, and lipidomic (multi-omic) studies are transforming our ability to understand and ...

Separation of Aldehydes and Reactive Ketones from Mixtures Using a Bisulfite Extraction Protocol

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer by generating a charged structure provides an opportunity to use extraction as a simple purification technique. By combining the use of a miscible organic solvent with saturated sodium bisulfite, aldehydes and reactive ketones can be successfully transformed into charged bisulfite adducts that can then be separated from other organic components of a mixture by the introduction of an immiscible organic layer. Here, we describe a simple protocol for the removal of aldehydes, including sterically-hindered neopentyl aldehydes and some ketones, from chemical mixtures. Ketones can be separated if they are sterically unhindered cyclic or methyl ketones. For aliphatic aldehydes and ketones, dimethylformamide is used as the miscible solvent to improve removal rates. The bisulfite addition reaction can be reversed by basification of the aqueous layer, allowing for the re-isolation of the reactive carbonyl component of a mixture.

Here, we present a protocol to remove aldehydes and reactive ketones from mixtures by a liquid-liquid extraction protocol directly with saturated sodium bisulfite in a miscible solvent. This combined protocol is rapid and facile to perform. The aldehyde or ketone can be re-isolated by the basification of the aqueous layer.

Separazione di aldeidi e chetoni reattive da miscele utilizzando un protocollo di estrazione di bisolfito

The purification of organic compounds is an essential component of routine synthetic operations. The ability to remove contaminants into an aqueous layer ...

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. Recently, we have developed a two-step strategy for ketone enolate umpolung that has enabled the development of methods for chlorination, azidation, and amination using azoles. In addition, we have developed C-C bond&#8211;forming arylation and allylation reactions. At the heart of these methods is the preparation of the intermediate and highly reactive enolonium species prior to addition of a reactive nucleophile. This strategy is thus reminiscent of the preparation and use of metal enolates in classical synthetic chemistry. This strategy allows the use of nucleophiles that would otherwise be incompatible with the strongly oxidizing hypervalent iodine reagents. In this paper we present a detailed protocol for chlorination, azidation, N-heteroarylation, arylation, and allylation. The products include motifs prevalent in medicinally active products. This article will greatly assist others in using these methods.

A two step one-pot protocol for the umpolung of ketone enolates to enolonium species and addition of a nucleophile to the &#945;-position is described. Nucleophiles include chloride, azide, azoles, allyl-silanes, and aromatic compounds.

Un protocollo in due fasi per Umpolung funzionalizzazione di chetoni Via Enolonium le specie

&#945;-Functionalization of ketones via umpolung of enolates by hypervalent iodine reagents is an important concept in synthetic organic chemistry. ...