TGK承认国际研究生院慕尼黑工业大学的科学与工程（IGGSE）提供的财政支持。香港承认的鼎力支持中心综合蛋白质科学慕尼黑（CIPSM）。

注:从供应商处获得的所有试剂和溶剂，无需进一步纯化即可使用。 注意:使用前请咨询所有相关材料安全数据表（MSDS）。进行化学合成（ 例如，通风柜，护目镜，手套，实验室外套，全长裤，不露脚趾的鞋子）时，请利用一切适当的安全设备。 1.胍基化的前体的合成<ol><li> 烷基化物种 <ol><li> 甲基化种 <ol><li>溶解将1.0g N，N&#39; -二叔丁氧羰基-1H-在10mL的干-吡唑-1-甲脒（3.2毫摩尔，1当量）和1.0克三苯基膦（PPH 3，3.8毫摩尔，1.2当量）在使用在室温下（RT）橡胶隔膜的惰性气氛的50mL圆底烧瓶中的四氢呋喃（THF）。使用注射器（4.8毫摩尔，1.5当量）和升添加无水甲醇194μL等它搅拌在RT。 </li><li>单独地，制备在小玻璃瓶中与747μL二异丙基偶氮二羧酸酯（DIAD，3.8毫摩尔，1.2当量）在2mL无水THF中的溶液。在搅拌的同时，用注射器（在15分钟）DIAD在THF滴加该溶液添加到的N，N&#39; -二叔丁氧羰甲基-1H-吡唑-1-甲脒，PPH 3和甲醇溶液中。让该溶液在RT下搅拌2个小时。 </li><li>除去使用旋转蒸发器减压除溶剂，将粗产物溶解在1mL的二氯甲烷（DCM）。在戊烷溶液加载闪式柱（2.5厘米×20厘米），在10％乙酸乙酯100g硅胶的（EtOAc）纯化。加载在柱的溶解的粗产物和压力（1.5巴）下加入溶剂。 </li><li>收集的级分（溶剂系统:等度10％的EtOAc在戊烷中），识别由薄层色谱（TLC）的所需化合物斑点，并收集它（R F = 0.4，乙酸乙酯/戊烷1:9，UV）。合并所需使用旋转蒸发器，以得到0.85g标题化合物，为黄色粘性油状物（2.6毫摩尔，81％收率）的级分并在减压下蒸发溶剂。存储在RT进一步使用，得到化合物。 </li></ol></li><li> 己胺改性品种 <ol><li>溶解1.0克N，N&#39; -二丁氧羰基-1H-吡唑-1-甲脒（3.2毫摩尔，1.0当量），将0.9g DDE -6-氨基己醇（3.8毫摩尔，1.2当量）的，和1.0克使用在室温下橡胶隔膜加入PPh 3（3.8毫摩尔，1.2当量）在10毫升在惰性气氛的50mL圆底烧瓶中的干燥THF中的。 </li><li>单独地，制备在小玻璃瓶中与747μL的DIAD（3.8毫摩尔，1.2当量）在2mL无水THF中的溶液。在搅拌的同时，DIAD在THF滴加该溶液添加到N的溶液，用注射器N&#39; -二叔丁氧羰甲基-1H-吡唑-1-甲脒，PPH 3，和DDE -6-氨基己醇（在15分钟内） 。让该溶液在RT下搅拌2个小时。 </li><li>除去使用旋转蒸发器减压除溶剂，采取在1毫升DCM中的粗产物的。在戊烷/ EtOAc中的溶液加载闪式柱（2.5厘米×20厘米）用100克二氧化硅（2:1）。适用于该列的溶解粗产物和压力（1.5巴）下添加溶剂。 </li><li>收集的级分（溶剂系统:等度2:1戊烷/ EtOAc）纯化，识别与TLC所需级分，并收集它们（R F = 0.66，2:1个戊烷/ EtOAc中，UV）。合并所需的部分并使用旋转蒸发器，得到1.6g的标题化合物，为黄色粘性油状物（2.8毫摩尔，产率88％）在减压下蒸发溶剂。存储在RT进一步使用，得到化合物。 </li></ol></li></ol></li><li> 酰化物种（2个反应步骤） <ol><li>溶解1.4克S- -methylisothiuronium半硫酸盐（10毫摩尔，1.0当量）和2.2克二（ 叔丁基）二碳酸酯（10毫摩尔，1.0当量）在剧烈搅拌响DCM的两相溶液/ 饱和水性 。 碳酸氢钠和让它在RT下搅拌24个小时。 </li><li>分离各层在分液漏斗和三次用DCM萃取水相。合并有机相，用Na 2 SO 4干燥它们，并使用旋转蒸发器在减压下除去溶剂。取在1毫升己烷的粗产物的。 </li><li> 1己烷/乙酸乙酯:以4:1的溶液加载闪式柱（2.5厘米×20厘米）用100克二氧化硅。加载在柱的溶解的粗产物。在压力下加入溶剂。识别与TLC（溶剂系统中的所希望的部分:4:1己烷等度/乙酸乙酯（检测UV:254纳米），并收集它们（R = 0.30）。 </li><li>合并所需的部分并使用旋转蒸发器，以获得1.1g标题化合物，为黄色粘性油状物（5.8毫摩尔，58％收率）在减压下蒸发溶剂。存储所述试剂，N - （ 叔丁氧羰） - S- -Methylisothiourea，在RT下供进一步使用。 </li><li>溶解250毫克N - （ 叔丁氧羰） -在10mL无水N，N-二甲基甲酰胺（DMF）s -methylisothiourea（1.3毫摩尔，1.0当量）在50mL的圆底烧瓶中，在惰性气氛中在RT。添加用注射器N，N-二异丙基乙胺（DIPEA）的440μL（2.6毫摩尔，2当量）。在搅拌的同时，添加245μLAC 2 O（5.2毫摩尔，4.0当量）的使用注射器逐滴并让它在RT下搅拌1个小时。 </li><li>过量的甲醇（2毫升）添加到使用注射器的混合物，并让它在RT下搅拌15分钟。除去使用旋转蒸发器在减压下除去溶剂。取在1毫升DCM中的粗产物的。 </li><li> 1己烷/乙酸乙酯3:在3溶液加载闪式柱（2.5厘米×20厘米）用60克二氧化硅1。溶解的粗产物施加到柱上。添加溶剂（3:1己烷/ EtOAc）和压力（1.5巴）。识别所需的级分用TLC（3:1己烷/乙酸乙酯，UV:220纳米），和colLECT他们（R F = 0.62）。 </li><li>合并所需的部分并使用旋转蒸发器，以获得210毫克的标题化合物，为白色固体（0.9毫摩尔，产率70％）在减压下蒸发溶剂。存储在RT以供进一步使用的化合物。 </li></ol></li></ol> 2.环肽前体的合成<ol><li> 装载和封盖TCP树脂 <ol><li>添加1.00克2- chlortriyl酰氯（CTC）树脂（0.9毫摩尔/克）和320毫克使Fmoc-Gly-OH（1.2当量）中的入塑料20毫升的注射器用玻璃料。制备313μLDIPEA（2个当量）在5mL无水DCM中的溶液并将其添加到所述注射器。让它转动，以便使用旋转单元在RT 1个小时。 </li><li>同时，准备5的2-mL溶液:1个甲醇/ DIPEA（V / V;封盖溶液）。添加封盖解决注射器，让它旋转，另外的15分钟。用DCM（5×）和DMF（3×）洗涤树脂。 </li></ol></li><li> 树脂上Fmoc去保护<ol><li>用DMF中的20％哌啶处理树脂结合使Fmoc-Gly 10分钟，然后5分钟。用DMF（3×）洗涤树脂。 </li></ol></li><li> 树脂上的Fmoc-ORN（DDE）的耦合-OH <ol><li>添加934毫克的Fmoc-L-ORN（DDE）-OH（2当量），684毫克1- [双（二甲基氨基）亚甲基] -1H-1,2,3-三唑并[4,5-B]吡啶鎓-3- OXID六氟磷酸盐（HATU）（2当量），和245毫克1-羟基-7-氮杂苯并三唑（加入HOAt）（2当量），以一个小的玻璃小瓶中，并在5毫升DMF中溶解。加入DIPEA的814μL。 </li><li>添加该溶液至Fmoc-脱保护的，洗涤和树脂结合的甘氨酸并让它旋转1个小时。用DMF（3×）洗涤树脂。 </li></ol></li><li> 树脂上Fmoc去保护 <ol><li>处理树脂结合的Fmoc-ORN（DDE）-Gly用在DMF中20％哌啶10分钟，然后5分钟。用DMF（3×）洗涤树脂。 </li></ol></li><li> 树脂上的Fmoc-VAL-OH的偶联 <ol><li>添加610毫克的Fmoc-VAL-OH（2当量），684毫克的HATU（2当量），和245毫克的加入HOAt（2当量），以一个小的玻璃小瓶中，并在5毫升DMF中溶解。加入DIPEA的814μL。 </li><li>此溶液添加到Fmoc基脱保护，洗涤和树脂结合的ORN（DDE）-Gly并让它旋转1个小时。 </li></ol></li><li> 树脂上Fmoc去保护 <ol><li>处理树脂结合的Fmoc-VAL-ORN（DDE）-Gly用在DMF中20％哌啶10分钟，然后5分钟。用DMF（3×）洗涤树脂。 </li></ol></li><li> 树脂上甲基化的N- <ol><li>用DCM（3×）洗涤树脂。在DCM中溶解887毫克2- nitrobenzenesulfonylchloride（ 邻 -NBS-CL，4当量），并添加1.2毫升2,4,6-三甲基吡啶（10当量）。 </li><li>添加该溶液到树脂结合的肽，并让它在室温下孵育20分钟。 </li><li>用CH 2 Cl 2（3×），并用THF（5×）洗涤树脂。制备具有1.18克的PPh 3（5当量）和在THF中的甲醇的365μL的溶液。收藏此解决注射器。 </li><li>在2mL THF中制备具有DIAD的883μL的溶液，并把它添加到注射器中。让它孵育15分钟。用THF（5×），用DMF（5×）洗涤树脂。 </li></ol></li><li> Ø-NS脱保护 <ol><li>准备用570μL巯基乙醇（10.0当量）和672μLdiazabicycloundecen的（DBU）在2mL DMF中的溶液。收藏此解决方案的注射器，让它孵化5分钟。 </li><li>重复脱保护步骤，然后用DMF（5×）洗涤树脂。 </li></ol></li><li> 树脂上的Fmoc-D-的Phe-OH的偶联 <ol><li>添加697毫克的Fmoc-D-PHE-OH（2当量），684毫克的HATU（2当量），和245毫克加入HOAt（2当量）的至小玻璃瓶中，并在5毫升DMF中的溶解。加入DIPEA的814μL。 </li><li>添加该溶液至Fmoc-脱保护的，洗涤和树脂结合的肽，并让它旋转1个小时。 </li></ol></li><li> 树脂上Fmoc去保护 <ol><li>治疗树脂-Bound用DMF中的20％哌啶10分钟，然后进行5分钟的肽。用DMF（3×）洗涤树脂。 </li></ol></li><li> 树脂上的Fmoc-天冬氨酸（OT丁基）-OH的偶联 <ol><li>添加741毫克的Fmoc-天冬氨酸（OT卜）-OH（2当量），（2当量），684毫克的HATU和245毫克加入HOAt（2当量）至小玻璃瓶中，将其溶解在5mL的DMF。加入DIPEA的814μL。 </li><li>添加该溶液至Fmoc-脱保护的，洗涤和树脂结合的肽，并让它旋转1个小时。 </li></ol></li><li> 从树脂上的线性肽的裂解 <ol><li>用DCM洗涤树脂（3x）和随后制备六氟异丙醇（HFIP）的DCM溶液的10毫升（1:4; V / V）。 </li><li>添加该溶液至树脂，让它旋转15分钟。收集在一个圆底烧瓶中的溶液。重复切割和使用旋转蒸发器蒸发溶剂。 </li></ol></li><li> 线性肽的环化 <ol><li>迪ssolve 384毫克的NaHCO 3（5.0当量）和叠氮磷酸二苯的582μL（DPPA）（3.0当量）在50mL DMF中的并将其添加到粗产物。让它搅拌过夜，或直到没有线性肽与ESI-MS（10小时）17观察到。 </li><li>在减压下，减少溶剂使用旋转蒸发器小体积。制备氯化钠（盐水）的饱和水溶液。使用巴斯德吸管，所述环化肽滴添加至40毫升饱和NaCl水溶液在一个离心管中。 </li><li>离心悬浮液（5000×g下，5分钟），并用HPLC级水（2×）洗涤沉淀物。冻干产品。 </li></ol></li></ol> 3.胍基化和脱保护解决方案<ol><li> 胍基与量身订做的前体 <ol><li>溶解在DMF中的小体积少量（ 例如，25毫克）的脱保护的正交环肽（ 例如，2米L）。添加2当量。的胍基化前体和2当量。 DIPEA的溶液中，并让它在RT下搅拌2个小时。 </li><li>监视与HPLC-MS的反应的进展。反应完成后，除去溶剂，再溶解guanidinylated环状在乙腈肽，并进行半制备型HPLC纯化16。 </li></ol></li><li> 酸不稳定的侧链保护基团的去除 <ol><li>制备2毫升含三氟乙酸（TFA），水和三异丙基硅烷（TIPS）的溶液（95 / 2.5 / 2.5; V / V / V）。添加该溶液到纯化的产物在一个小的玻璃瓶中并让它在室温搅拌至少1小时。观察与ESI-MS 17的完全脱保护。 </li><li>在减压下蒸发溶剂至小体积。制备冰冷醚和在50毫升离心管中加入10毫升。通过添加它沉淀使用巴氏吸管在冰冷醚去保护的肽滴。离心悬浮液（5000×g下，5分钟），得到颗粒。 </li><li>洗用冰冷的乙醚沉淀和离心它（5000×g下，5分钟，2次）。溶解产物在2毫升的HPLC级水中，用半制备型HPLC纯化16它。 </li></ol></li></ol> 4.分析数据和用于纯化参数<ol><li> 分析性HPLC-ESI-MS <ol><li>使用C18柱（12纳米孔径3μm的粒径，125毫米×2.1毫米）或C8柱（20纳米的孔径，5μm的粒子的LCQ质谱仪进行分析型HPLC-ESI-MS尺寸，250毫米×2.1毫米），用H 2 O（0.1％v / v甲酸）/乙腈（0.1％v / v甲酸）作为洗脱剂。 </li></ol></li><li> 半制备性HPLC <ol><li>用ODS-A柱（20×250毫米，5微米），8毫升/分钟的流速，和线性渐变执行使用制备型HPLC仪器半制备性HPLC的H 2 O（0.1％V / V TFA）和乙腈（0.1％体积/体积TFA）。 </li></ol></li></ol>

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Cell Biol. 197 (1), 131-140 (2012).</li><li>Hersel, U., Dahmen, C., Kessler, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RGD+modified+polymers:+biomaterials+for+stimulated+cell+adhesion+and+beyond.">RGD modified polymers: biomaterials for stimulated cell adhesion and beyond.</a> Biomaterials. 24 (24), 4385-4415 (2003).</li><li>Auernheimer, J., Dahmen, C., Hersel, U., Bausch, A., Kessler, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoswitched+Cell+Adhesion+on+Surfaces+with+RGD+Peptides.">Photoswitched Cell Adhesion on Surfaces with RGD Peptides.</a> J. Am. Chem. Soc. 127 (46), 16107-16110 (2005).</li><li>Corradini, D., Eksteen, E., Eksteen, R., Schoenmakers, P., Miller, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of HPLC. , (2011).</li><li>de Hoffmann, E., Stroobant, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Mass Spectrometry: Principles and Applications. , (2007).</li><li>Frank, A. O., 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=Conformational+Control+of+Integrin-Subtype+Selectivity+in+isoDGR+Peptide+Motifs:+A+Biological+Switch.">Conformational Control of Integrin-Subtype Selectivity in isoDGR Peptide Motifs: A Biological Switch.</a> Angew. Chem. Int. Ed. 49 (48), 9278-9281 (2010).</li><li>Rossiter, S., 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=Selective+substrate-based+inhibitors+of+mammalian+dimethylarginine+dimethylaminohydrolase.">Selective substrate-based inhibitors of mammalian dimethylarginine dimethylaminohydrolase.</a> J. Med. Chem. 48 (14), 4670-4678 (2005).</li><li>Weiss, S., Keller, M., Bernhardt, G., Buschauer, A., K&#246;nig, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N(G)-Acyl-argininamides+as+NPY+Y(1)+receptor+antagonists:+Influence+of+structurally+diverse+acyl+substituents+on+stability+and+affinity.">N(G)-Acyl-argininamides as NPY Y(1) receptor antagonists: Influence of structurally diverse acyl substituents on stability and affinity.</a> Bioorg. Med. Chem. 18 (17), 6292-6304 (2010).</li><li>Hammerschmidt, F., Kvaternik, H., Schweifer, A., Mereiter, K., Aigner, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+Synthesis+of+No-Carrier-Added+[*I]MIBG+and+Its+Precursor.">Improved Synthesis of No-Carrier-Added [*I]MIBG and Its Precursor.</a> Synthesis. 44 (21), 3387-3391 (2012).</li></ol>

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为胍基化的前体是正交脱保护的环肽衍生物，（C（OrnD（OT丁基）GF（N Me）的V）），这是通过固相肽合成（SPPS）的标准Fmoc方案合成。鸟氨酸被用作正交保护的衍生物，羰基（Fmoc-ORN（DDE）-OH），其可以与肼在DMF中的肽支架的环化反应后进行脱保护。该肽的前体是由化合物沉淀，并通过随后的冷冻干燥纯化。 为胍基烷基化的前体可以在在一步反应良好的产率从商业上可获得的物质起始Ñ，N&#39; -二叔丁氧羰基-1H-通过在Mitsunobu条件下进行烷基化反应-吡唑-1-甲脒（PPH 3来获得，DIAD，THF）19，10。有了这个反应，种类繁多的前体是ACCEssible由相应的醇。与烷基化的前体的胍基化反应产生在一个干净的反应所定义的产物。如果反应物的完全转化在2个小时后，未观察到，该反应应当继续。下的协议中给出的条件下，只有轻微的副产物形成的;然而，更高的量的杂质不能排除所有，特别是不同的保护，携带更大的部分的基板。 如果使用胍官能化肽（更长的接头）时，DDE保护基上的连接体的末端胺被移除，并且可以通过酰胺偶合缀合成相应的酸。 DDE的脱保护中的2％肼在DMF中的溶液中进行，并产生正交脱保护肽，其应该在进一步使用之前进行纯化（ 例如，半制备型HPLC）。在这种情况下，一个简单的乙酰化反应原位进行。 如果使用乙酰化胍，不同前体的战略应适用。选自S -methylisothiourea开始，两步反应顺序需要20。首先，必须乙酰化之前用选择的一种酸（在此，乙酸）中进行21 号第 -methylisothiourea的单保护的Boc。的胍基化反应是一个非常干净的和快的反应，酸不稳定的侧链保护基团的最终脱保护后得到最终的化合物。 如在引言中已经说明的，该方法允许对任何肽胍基的修饰和官能化。我们证明这种技术在整合素配体，其允许，在这种情况下，配位体的亚型选择性的调整。未修饰的整联蛋白拮抗剂是西仑吉肽双选择性为素αvβ3/α5β1亚型。通过的端子Nω的甲基化胍基，联蛋白αvβ3选择性配体产生。这阻止了在α5β1唯一地观察到，因而灭活该整联配体的重要端上的相互作用。与素αvβ3亚型的结合位点的主要相互作用是一种端上相互作用不是由这种相互作用10干扰。 通过具有较长的接头单元修改所述配体（"官能化"），两个目标可以一气呵成达到:产生选择性通过与α5β1亚型打破端上的相互作用和，在另一侧，连接体指出的结合袋，允许缀合到大的实体（ 例如，螯合剂或用于成像技术的荧光染料）10。

其中在天然配体中最丰富的药效基团是胍基，其参与多种相互作用1,2。例如，它可作为在氢键相互作用的电位四倍氢供体并参与静电相互作用，例如盐桥或阳离子-π相互作用。在药物化学，该组中的药物和药物候选4，经常发现，虽然很常作为胍模拟物5,6。其原因胍模拟物的开发是去除普遍存在的，带正电荷的胍基团，以及作为配体的亲脂性的调整。在肽配体，唯一的胍基的氨基酸是精氨酸，其因此通常在肽配体的生物活性区域中发现。 一个非常PR用于含精氨酸的配体家族ominent例子是RGD结合整联亚家族。通常，整联是一类细胞粘附受体，它们接管重要的功能在所有高等生物的。其中的一些功能，包括细胞粘附，迁移和细胞存活。因此，它们也参与病理指示，诸如癌症和纤维化。整合素是选自由α-和β亚单位构成24个目前已知的整联亚型的异源二聚体跨膜蛋白;其中8识别的三肽序列精氨酸-甘氨酸-天冬氨酸（RGD =）在它们的配体7。所述结合区域位于在细胞外部分，即所谓的整头组8这两个亚型之间的接口。 RGD由两个共同相互作用确认:金属离子依赖性的粘附位点（MIDAS）区域，该区域位于β亚基和结合在配体的羧酸（侧茶在ASP的）;和胍组中的配体，其位于α亚基。大多数整联亚型是混杂和共享至少它们的天然细胞外基质（ECM）配体9的一部分。因此，人工整合素配体的发展，主要的焦点是，除了具有高结合亲和力的亚型选择性。最近，我们能够出台针对亚型选择性配体的产生的关键因素:胍组。通过不同的修饰，所述αv-和双选择性配体α5含整亚型可以通过简单的修改的胍基团，然后它可以区分不同的α亚基10变成选择性的化合物。 在αV的口袋，所述胍基经由二齿盐桥与Asp218 11,12相互作用侧面上 。这种相互作用Ç一个也α5β1可以观察到（在此，用Asp227在α5），但是另外，端部上有Gln残基（Gln221）的胍基团的相互作用，观察到有13。因此，我们修改了胍组中的两个相对的方式:在一种情况下，通过与胍基的Nδ的甲基化阻止侧上相互作用，而在其他情况下，与胍Nω的甲基化，阻断端上的相互作用。出人意料的是，这个小的修改导致了配体完整的选择性转变。除了烷基化，新功能化方法本出版物中介绍。对于这种类型的配体pentapeptidic的经典官能的方法是通过不参与结合的氨基酸的侧链共轭（ 例如，K在C（RGDfK））14，15。这里，我们表明，官能化也可以通过修改胍 - 这对于结合至关重要 - 与酰基或烷基化连接基。上的正电荷，对于结合是必需被保留，并且模型表明，长链分出来的结合口袋的，因此提供进一步的接头的附接的理想可能性和标记单元（ 例如，荧光标记物或分子螯合剂成像）。 在这项工作中，我们集中在对于胍基的含精氨酸的配体的变形例的制备步骤。这涉及Nω甲基化的物质的合成，以及与较长的接头单元胍。不同的修饰包括酰基和烷基。

<table><tbody><tr><td>&lt;em&gt;N,N&amp;prime;&lt;/em&gt;-Di-Boc-1H-pyrazole-1-carboxamidine, 98%&amp;nbsp;</td><td>Sigma Aldrich</td><td>434167&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>Triphenylphosphine, 99%</td><td>Sigma Aldrich</td><td>T84409&amp;nbsp;SIGMA-ALDRICH</td><td></td></tr><tr><td>Tetrahydrofuran, &gt;99.5%</td><td>Carl Roth</td><td>4745</td><td></td></tr><tr><td>Tetrahydrofuran anhydrous, 99.8%</td><td>Carl Roth</td><td>5182</td><td></td></tr><tr><td>Methanol anhydrous, 99.8%</td><td>Sigma Aldrich</td><td>322415&amp;nbsp;SIGMA-ALDRICH</td><td></td></tr><tr><td>Diisopropyl azodicarboxylate, 98%</td><td>Sigma Aldrich</td><td>225541&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>Dichlormethan, for synthesis, 99.5%</td><td>Carl Roth</td><td>8424</td><td></td></tr><tr><td>Silica gel for flash chromtaography</td><td>Sigma Aldrich</td><td>60738&amp;nbsp;SIGMA-ALDRICH</td><td></td></tr><tr><td>n-Pentane, 99%</td><td>Carl Roth</td><td>8720</td><td></td></tr><tr><td>n-Hexane, 99%</td><td>Carl Roth</td><td>CP47</td><td></td></tr><tr><td>Ethylacetate, 99.5%</td><td>Carl Roth</td><td>7338</td><td></td></tr><tr><td>Aminohexanol, 95%</td><td>Sigma Aldrich</td><td>A56353&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>&lt;em&gt;S&lt;/em&gt;-Methylisothiourea hemisulfate, 98%</td><td>Sigma Aldrich</td><td>M84445 ALDRICH</td><td></td></tr><tr><td>Di-&lt;em&gt;tert&lt;/em&gt;-butyl dicarbonate, 99%</td><td>Sigma Aldrich</td><td>205249&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>&lt;em&gt;N,N&lt;/em&gt;-Dimethylformamid, 99.8%</td><td>Carl Roth</td><td>A529</td><td></td></tr><tr><td>&lt;em&gt;N,N&lt;/em&gt;-Diisopropylethylamin, 99.5%</td><td>Carl Roth</td><td>2474</td><td></td></tr><tr><td>Acetic anhydrid, 99%</td><td>Carl Roth</td><td>4483</td><td></td></tr><tr><td>Chlortrityl resin</td><td>Carbolution</td><td>CC11006</td><td></td></tr><tr><td>Fmoc-Gly-OH, 98%</td><td>Carbolution</td><td>CC05014</td><td></td></tr><tr><td>Piperidin, 99%</td><td>Sigma Aldrich</td><td>104094&amp;nbsp;SIGMA-ALDRICH</td><td></td></tr><tr><td>Fmoc-Orn(Dde)-OH</td><td>Iris-Biotech</td><td>FAA1502</td><td></td></tr><tr><td>HATU, 99%</td><td>Carbolution</td><td>CC01011</td><td></td></tr><tr><td>HOAt, 99%</td><td>Carbolution</td><td>CC01004</td><td></td></tr><tr><td>Fmoc-Val-OH</td><td>Carbolution</td><td>CC05028</td><td></td></tr><tr><td>2-Nitrobenzenesulfonyl chloride, 97%</td><td>Sigma Aldrich</td><td>N11507&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>2,4,6-Collidine, 99%</td><td>Sigma Aldrich</td><td>27690&amp;nbsp;SIGMA-ALDRICH</td><td></td></tr><tr><td>Mercaptoethanol, 99%&amp;nbsp;</td><td>Sigma Aldrich</td><td>M6250&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>Diazabicycloundecen, 98%</td><td>Sigma Aldrich</td><td>139009&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>Fmoc-D-Phe-OH, 98%</td><td>Sigma Aldrich</td><td>47378&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>Fmoc-Asp(OtBu)-OH, 98%</td><td>Carbolution</td><td>CC05008</td><td></td></tr><tr><td>Hexafluoroisopropanol</td><td>Carbolution</td><td>CC03056</td><td></td></tr><tr><td>Diphenylphosphoryl azide, 97%</td><td>Sigma Aldrich</td><td>178756&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>TFA, 99.9%</td><td>Carl Roth</td><td>P088</td><td></td></tr><tr><td>Triisopropylsilan, 98%</td><td>Sigma Aldrich</td><td>233781&amp;nbsp;ALDRICH</td><td></td></tr><tr><td>Acetonitrile, HPLC grade</td><td>Carl Roth</td><td>HN44</td><td></td></tr></tbody></table>

modification and functionalization of the guanidine group by tailor-made precursors

胍组是在药物化学中最重要的药效基团之一。携带胍基的唯一的氨基酸是精氨酸。在本文中，提供了一种用于在肽配体的胍基的修饰的简单方法，用RGD结合整联配体的一个例子。据最近表明，胍基团在这些配位体的不同修改允许亚型的选择性调节（ 例如，αV亚型和α5之间）。此外，通过胍基的功能化以前未知的策略被证明，而合成的方法在本文件中审查。这里所描述的修改涉及末端（Nω）烷基化和乙酰化胍基。用于合成，量身定做的前体分子被合成，然后将其进行反应与正交脱保护的胺来传送预修饰胍组。对于烷基化胍的合成中，基于N-前体，N&#39; -二叔丁氧羰甲基-1H-吡唑-1-甲脒用于合成酰化化合物，选择为N -Boc- S的相应的酰化衍生物的前体-甲基异硫脲，其可以在一个和两个步骤的反应来获得。

环肽前体合成的线性肽，环化，和正交DDE脱保护。在沉淀后，所述化合物的纯度用HPLC-MS（ 图1）进行分析。以监测反应的进展，2小时的反应时间（ 图2）之后进行的HPLC分析。 有关胍基残基较大，在2小时反应时间通常是不够的。在这种情况下，继续反应，并用LC-MS监测。进行反应和最终的脱保护后，使用半制备型HPLC设备（产率通常在低毫克范围）纯化的化合物。最终化合物用HPLC-MS进行分析，以评估纯度（参见图3）。 少量称重到微量离心管中，并稀释<html>用DMSO以获得用于在ELISA状，固相结合分析中的化合物的生物学评价的杆溶液。结果示于图4中描绘。标准分子西仑吉肽（未修饰的胍基团）被包括作为参考。所有化合物对整联蛋白αvβ3亚型和高选择性对α5β1的相对高的亲和力。 <img alt="图1" src="/files/ftp_upload/54873/54873fig1.jpg" /> 图1:HPLC-MS谱:正交DDE脱保护的衍生物的C（梯度10-90％乙腈（ACN）中的两相溶剂体系中与H 2 O和ACN）（OrnGD（OT丁基）F（N我）V ）（计算质量:602.34克/摩尔），线性肽进行环化反应后得到，随后的DDE脱保护，和沉淀。ANK"&gt;点击此处查看该图的放大版本。 <img alt="图2" src="/files/ftp_upload/54873/54873fig2.jpg" /> 图2:HPLC-MS谱（梯度:10-90％ACN在两相溶剂体系用H 2 O和ACN）正交脱保护的环肽的胍基化反应和胍基化甲基化前体后，将反应混合物的。除了产物峰（R T = 7.50分钟，计算质量=858.49克/摩尔），仅过量胍基化的前体（R T = 6.38分钟）和碱DIPEA（R T = 0.90分钟）的可观察到。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54873/54873fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/54873/54873fig3.jpg" /> 图3:脱保护后的粗化合物2（R T = 3.69分钟，计算质量=603.32克/摩尔）:HPLC-MS谱（10-90％ACN在用H 2 O和ACN的双相溶剂系统梯度）之前的半制备纯化的对酸不稳定的侧链。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54873/54873fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/54873/54873fig4.jpg" /> 图4:在溶液和生物学评价胍的官能化。复合 1，具有未改变的胍基，是西仑吉肽。在该手稿解决的修饰是本甲基化的（2）中 ，官能化（在此，乙酰氨基己烷; 3），和乙酰化（4）的衍生物。 Ť他结合亲和力使用分离的蛋白质18固相结合测定来确定。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54873/54873fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

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Modification and Functionalization of the Guanidine Group by Tailor-made Precursors

一种用于基于使用所述相应的前体的烷基改性胍的合成方案被呈现。

修改和胍集团的官能通过量身定制的前兆

The guanidine group is one of the most important pharmacophoric groups in medicinal chemistry. The only amino acid carrying a guanidine group is arginine. ...

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视频: Modification and Functionalization of the Guanidine Group by Tailor-made Precursors

Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

One of the main benefits to using poly(ethylene glycol) (PEG) macromers in hydrogel formation is synthetic versatility. The ability to draw from a large variety of PEG molecular weights and configurations (arm number, arm length, and branching pattern) affords researchers tight control over resulting hydrogel structures and properties, including Young&#8217;s modulus and mesh size. This video will illustrate a rapid, efficient, solvent-free, microwave-assisted method to methacrylate PEG precursors into poly(ethylene glycol) dimethacrylate (PEGDM). This synthetic method provides much-needed starting materials for applications in drug delivery and regenerative medicine. The demonstrated method is superior to traditional methacrylation methods as it is significantly faster and simpler, as well as more economical and environmentally friendly, using smaller amounts of reagents and solvents. We will also demonstrate an adaptation of this technique for on-resin methacrylamide functionalization of peptides. This on-resin method allows the N-terminus of peptides to be functionalized with methacrylamide groups prior to deprotection and cleavage from resin. This allows for selective addition of methacrylamide groups to the N-termini of the peptides while amino acids with reactive side groups (e.g.&#160;primary amine of lysine, primary alcohol of serine, secondary alcohols of threonine, and phenol of tyrosine) remain protected, preventing functionalization at multiple sites. This article will detail common analytical methods (proton Nuclear Magnetic Resonance spectroscopy (;H-NMR) and Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-ToF)) to assess the efficiency of the functionalizations. Common pitfalls and suggested troubleshooting methods will be addressed, as will modifications of the technique which can be used to further tune macromer functionality and resulting hydrogel physical and chemical properties. Use of synthesized products for the formation of hydrogels for drug delivery and cell-material interaction studies will be demonstrated, with particular attention paid to modifying hydrogel composition to affect mesh size, controlling hydrogel stiffness and drug release.

Microwave-assisted Functionalization of Polyethylene glycol and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

This video will illustrate a rapid, efficient method to methacrylate poly(ethylene glycol), enabling chain polymerizations and hydrogel synthesis. It will demonstrate how to similarly introduce methacrylamide functionalities into peptides, detail common analytical methods to assess functionalization efficiency, provide suggestions for troubleshooting and advanced modifications, and demonstrate typical hydrogel characterization techniques.

保利的微波辅助功能化（乙二醇）和On-树脂链聚合反应，并形成水凝胶的肽使用

One of the main benefits to using poly(ethylene glycol) (PEG) macromers in hydrogel formation is synthetic versatility. The ability to draw from a large ...

科研

化学

Nucleoside Triphosphates - From Synthesis to Biochemical Characterization

The traditional strategy for the introduction of chemical functionalities is the use of solid-phase synthesis by appending suitably modified phosphoramidite precursors to the nascent chain. However, the conditions used during the synthesis and the restriction to rather short sequences hamper the applicability of this methodology. On the other hand, modified nucleoside triphosphates are activated building blocks that have been employed for the mild introduction of numerous functional groups into nucleic acids, a strategy that paves the way for the use of modified nucleic acids in a wide-ranging palette of practical applications such as functional tagging and generation of ribozymes and DNAzymes. One of the major challenges resides in the intricacy of the methodology leading to the isolation and characterization of these nucleoside analogues.
	
	In this video article, we present a detailed protocol for the synthesis of these modified analogues using phosphorous(III)-based reagents. In addition, the procedure for their biochemical characterization is divulged, with a special emphasis on primer extension reactions and TdT tailing polymerization. This detailed protocol will be of use for the crafting of modified dNTPs and their further use in chemical biology.

The protocol described herein aims to explain and abridge the numerous obstacles in the way of the intricate route leading to modified nucleoside triphosphates. Consequently, this protocol facilitates both the synthesis of these activated building-blocks and their availability for practical applications.

核苷三磷酸 - 从合成到生化特征

The  traditional strategy for the introduction of chemical functionalities is the  use of solid-phase synthesis by appending suitably modified ...

High-throughput Synthesis of Carbohydrates and Functionalization of Polyanhydride Nanoparticles

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design efficacious vaccines carriers. Nanoparticle-based platforms can prolong the persistence of vaccine antigens, which could improve vaccine immunogenicity1. Several biodegradable polymers have been studied as vaccine delivery vehicles1; in particular, polyanhydride particles have demonstrated the ability to provide sustained release of stable protein antigens and to activate antigen presenting cells and modulate immune responses2-12.
The molecular design of these vaccine carriers needs to integrate the rational selection of polymer properties as well as the incorporation of appropriate targeting agents. High throughput automated fabrication of targeting ligands and functionalized particles is a powerful tool that will enhance the ability to study a wide range of properties and will lead to the design of reproducible vaccine delivery devices.
The addition of targeting ligands capable of being recognized by specific receptors on immune cells has been shown to modulate and tailor immune responses10,11,13 C-type lectin receptors (CLRs) are pattern recognition receptors (PRRs) that recognize carbohydrates present on the surface of pathogens. The stimulation of immune cells via CLRs allows for enhanced internalization of antigen and subsequent presentation for further T cell activation14,15. Therefore, carbohydrate molecules play an important role in the study of immune responses; however, the use of these biomolecules often suffers from the lack of availability of structurally well-defined and pure carbohydrates. An automation platform based on iterative solution-phase reactions can enable rapid and controlled synthesis of these synthetically challenging molecules using significantly lower building block quantities than traditional solid-phase methods16,17.
Herein we report a protocol for the automated solution-phase synthesis of oligosaccharides such as mannose-based targeting ligands with fluorous solid-phase extraction for intermediate purification. After development of automated methods to make the carbohydrate-based targeting agent, we describe methods for their attachment on the surface of polyanhydride nanoparticles employing an automated robotic set up operated by LabVIEW as previously described10. Surface functionalization with carbohydrates has shown efficacy in targeting CLRs10,11 and increasing the throughput of the fabrication method to unearth the complexities associated with a multi-parametric system will be of great value (Figure 1a).

In this article, a high throughput method is presented for the synthesis of oligosaccharides and their attachment to the surface of polyanhydride nanoparticles for further use in targeting specific receptors on antigen presenting cells.

碳水化合物和聚酸酐纳米粒子功能化的高通量合成

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design ...

生物工程

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.

一个直接的，早期胍基协议的复杂含氨基胍，天然产物合成

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

Facile Preparation of 4-Substituted Quinazoline Derivatives

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted 2-aminobenzophenones and thiourea in the presence of dimethyl sulfoxide (DMSO). This is a unique complementary reaction system in which thiourea undergoes thermal decomposition to form carbodiimide and hydrogen sulfide, where the former reacts with 2-aminobenzophenone to form 4-phenylquinazolin-2(1H)-imine intermediate, whilst hydrogen sulfide reacts with DMSO to give methanethiol or other sulfur-containing molecule which then functions as a complementary reducing agent to reduce 4-phenylquinazolin-2(1H)-imine intermediate into 4-phenyl-1,2-dihydroquinazolin-2-amine. Subsequently, the elimination of ammonia from 4-phenyl-1,2-dihydroquinazolin-2-amine affords substituted quinazoline derivative. This reaction usually gives quinazoline derivative as a single product arising from 2-aminobenzophenone as monitored by GC/MS analysis, along with small amount of sulfur-containing molecules such as dimethyl disulfide, dimethyl trisulfide, etc. The reaction usually completes in 4-6 hr at 160 &#186;C in small scale but may last over 24 hr when carried out in large scale. The reaction product can be easily purified by means of washing off DMSO with water followed by column chromatography or thin layer chromatography.

A protocol for facile preparation of 4-substituted quinazoline derivatives from 2-aminobenzophenones, thiourea and dimethyl sulfoxide is presented.

的4-取代喹唑啉衍生物简便制备

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted ...

Chemoselective Modification of Viral Surfaces via Bioorthogonal Click Chemistry

The modification of virus particles has received a significant amount of attention for its tremendous potential for impacting gene therapy, oncolytic applications and vaccine development.1,2,3 Current approaches to modifying viral surfaces, which are mostly genetics-based, often suffer from attenuation of virus production, infectivity and cellular transduction.4,5 Using chemoselective click chemistry, we have developed a straightforward alternative approach which sidesteps these issues while remaining both highly flexible and accessible.1,2
The goal of this protocol is to demonstrate the effectiveness of using bioorthogonal click chemistry to modify the surface of adenovirus type 5 particles. This two-step process can be used both therapeutically1 or analytically,2,6 as it allows for chemoselective ligation of targeting molecules, dyes or other molecules of interest onto proteins pre-labeled with azide tags. The three major advantages of this method are that (1) metabolic labeling demonstrates little to no impact on viral fitness,1,7 (2) a wide array of effector ligands can be utilized, and (3) it is remarkably fast, reliable and easy to access.1,2,7
In the first step of this procedure, adenovirus particles are produced bearing either azidohomoalanine (Aha, a methionine surrogate) or the unnatural sugar O-linked N-azidoacetylglucosamine (O-GlcNAz), both of which contain the azide (-N3) functional group. After purification of the azide-modified virus particles, an alkyne probe containing the fluorescent TAMRA moiety is ligated in a chemoselective manner to the pre-labeled proteins or glycoproteins. Finally, an SDS-PAGE analysis is performed to demonstrate the successful ligation of the probe onto the viral capsid proteins. Aha incorporation is shown to label all viral capsid proteins (Hexon, Penton and Fiber), while O-GlcNAz incorporation results in labeling of Fiber only.
In this evolving field, multiple methods for azide-alkyne ligation have been successfully developed; however only the two we have found to be most convenient are demonstrated herein &#x2013; strain-promoted azide-alkyne cycloaddition (SPAAC) and copper-catalyzed azide-alkyne cycloaddition (CuAAC) under deoxygenated atmosphere.

Adenovirus particles are engineered to contain either the unnatural amino acid analogue azidohomoalanine or the azido sugar O-GlcNAz. The azide group of each is chemoselectively ligated via "click" chemistry reactions as a means of viral surface modification.

通过Bioorthogonal点击化学化学选择性病毒表面改性

The modification of virus particles has received a significant amount of attention for its tremendous potential for impacting gene therapy, oncolytic ...

免疫与感染

Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines

Decomposition of N-tosyl-1,2,3-triazoles with rhodium(II) acetate dimer in the presence of alcohols forms synthetically versatile N-(2-alkoxyvinyl)sulfonamides, which react under a variety of conditions to afford useful N- and O-containing compounds. Acid-catalyzed addition of alcohols or thiols to N-(2-alkoxyvinyl)sulfonamide-containing phthalans provides access to ketals and thioketals, respectively. Selective reduction of the vinyl group in N-(2-alkoxyvinyl)sulfonamide-containing phthalans via hydrogenation yields the corresponding phthalan in good yield, whereas reduction with sodium bis(2-methoxyethoxy)aluminumhydride generates a ring-opened phenethylamine analogue. Because the N-(2-alkoxyvinyl)sulfonamide functional group is synthetically versatile, but often hydrolytically unstable, this protocol emphasizes key techniques in preparing, handling, and reacting these pivotal substrates in several useful transformations.

Preparation of N-2-alkoxyvinylsulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines

Representative experimental procedures for the synthesis of N-(2-alkoxyvinyl)sulfonamides and subsequent conversion to phthalan and phenethylamine derivatives are presented in detail.

准备n-(2-alkoxyvinyl) 磺胺从n-tosyl-1,2,3-triazoles 和随后转换为取代 Phthalans 和 Phenethylamines

Decomposition of N-tosyl-1,2,3-triazoles with rhodium(II) acetate dimer in the presence of alcohols forms synthetically versatile ...

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Disaccharide nucleosides, which consist of disaccharide and nucleobase moieties, have been known as a valuable group of natural products having multifarious bioactivities. Although chemical O-glycosylation is a commonly beneficial strategy to synthesize disaccharide nucleosides, the preparation of substrates such as glycosyl donors and acceptors requires&#160;tedious protecting&#160;group manipulations and a purification at each synthetic step. Meanwhile, several research groups have reported that boronic and borinic esters serve as a protecting or activating group of carbohydrate derivatives to achieve the regio- and/or stereoselective acylation, alkylation, silylation, and glycosylation. In this article, we demonstrate the procedure for the regioselective O-glycosylation of unprotected ribonucleosides utilizing boronic acid. The esterification of 2&#39;,3&#39;-diol of ribonucleosides with boronic acid makes the temporary protection of diol, and, following O-glycosylation with a glycosyl donor in the presence of p-toluenesulfenyl chloride and silver triflate, permits the regioselective reaction of the 5&#39;-hydroxyl group to afford the disaccharide nucleosides. This method could be applied to various nucleosides, such as guanosine, adenosine, cytidine, uridine, 5-metyluridine, and 5-fluorouridine. This article and the accompanying video represent&#160;useful (visual) information for the O-glycosylation of unprotected nucleosides and their analogs for the synthesis of not only disaccharide nucleosides, but also a variety of biologically relevant derivatives.

Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides

Here, we present protocols for the synthesis of disaccharide nucleosides by the regioselective O-glycosylation of ribonucleosides via a temporary protection of their 2&#39;,3&#39;-diol moieties utilizing a cyclic boronic ester. This method applies to several unprotected nucleosides such as adenosine, guanosine, cytidine, uridine, 5-methyluridine, and 5-fluorouridine to give corresponding disaccharide nucleosides.

苷 2 ', 3 ' -二醇酯对双糖苷合成的选择性O-糖基化

Disaccharide nucleosides, which consist of disaccharide and nucleobase moieties, have been known as a valuable group of natural products having ...

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyl(tropone)iron

aza-Michael adducts of tricarbonyl(tropone)iron are synthesized by two different methods. Primary aliphatic amines and cyclic secondary amines participate in a direct aza-Michael reaction with tricarbonyl(tropone)iron under solvent-free conditions. Less nucleophilic aniline derivatives and more hindered secondary amines add efficiently to the cationic tropone complex formed by protonation of tricarbonyl(tropone)iron. While the protocol utilizing the cationic complex is less efficient overall for accessing the aza-Michael adducts than the direct, solvent-free addition to the neutral complex, it allows the use of a broader range of amine nucleophiles. Following protection of the amine of the aza-Michael adduct as a tert-butyl carbamate, the diene is decomplexed from the iron tricarbonyl fragment upon treatment with cerium(IV) ammonium nitrate to provide derivatives of 6-aminocyclohepta-2,4-dien-1-one. These products can serve as precursors to diverse compounds containing a seven-membered carbocyclic ring. Because the demetallation requires protection of the amine as a carbamate, the aza-Michael adducts of secondary amines cannot be decomplexed using the protocol described here.

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyltroponeiron

Representative experimental procedures for the addition of amine nucleophiles to tricarbonyl(tropone)iron and subsequent demetallation of the resulting complexes are presented in detail.

通过三碳基(特罗酮)铁制备6-氨基环丙烯-2,4-dien-1-1衍生物

aza-Michael adducts of tricarbonyl(tropone)iron are synthesized by two different methods. Primary aliphatic amines and cyclic secondary amines participate ...

The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications

The use of polymers as biomaterials has provided significant advantages in therapeutic applications. In particular, the possibility to modify and functionalize polymer chains with compounds that are able to improve biocompatibility, mechanical properties, or cell viability allows the design of novel materials to meet new challenges in the biomedical field. With the polymer functionalization strategies, click chemistry is a powerful tool to improve cell-compatibility and drug delivery properties of polymeric devices. Similarly, the fundamental need of biomedicine to use sterile tools to avoid potential adverse-side effects, such as toxicity or contamination of the biological environment, gives rise to increasing interest in the microwave-assisted strategy.
The combination of click chemistry and the microwave-assisted method is suitable to produce biocompatible hydrogels with desired functionalities and improved performances in biomedical applications. This work aims to synthesize RGD-functionalized hydrogels. RGD (arginylglycylaspartic acid) is a tripeptide that can mimic cell adhesion proteins and bind to cell-surface receptors, creating a hospitable microenvironment for cells within the 3D polymeric network of the hydrogels. RGD functionalization occurs through Huisgen 1,3-dipolar cycloaddition. Some PAA carboxyl groups are modified with an alkyne moiety, whereas RGD is functionalized with azido acid as the terminal residue of the peptide sequence. Finally, both products are used in a copper catalyzed click reaction to permanently link the peptide to PAA. This modified polymer is used with carbomer, agarose and polyethylene glycol (PEG) to synthesize a hydrogel matrix. The 3D structure is formed due to an esterification reaction involving carboxyl groups from PAA and carbomer and hydroxyl groups from agarose and PEG through microwave-assisted polycondensation. The efficiency of the gelation mechanism ensures a high degree of RGD functionalization. In addition, the procedure to load therapeutic compounds or biological tools within this functionalized network is very simple and reproducible.

We present a protocol for the synthesis of RGD-functionalized hydrogels as devices for cell and drug delivery. The procedure involves copper catalyzed alkyne-azide cycloaddition (CuAAC) between alkyne-modified polyacrylic acid (PAA) and a RGD-azide derivative. The hydrogels are formed using microwave-assisted polycondensation and their physicochemical properties are investigated.