The <i>ortho</i>-substituent on 2,4-bis(trifluoromethyl)phenylboronic acid catalyzed dehydrative condensation between carboxylic acids and amines
作者:Ke Wang、Yanhui Lu、Kazuaki Ishihara
DOI:10.1039/c8cc02558d
日期:——
2,4-Bis(trifluoromethyl)phenylboronic acid is a highly effective catalyst for dehydrative amidation between carboxylic acids and amines. Mechanistic studies suggest that a 2 : 2 mixed anhydride is expected to be the only active species, and the ortho-substituent of boronic acid plays a key role in preventing the coordination of amines to the boron atom of the active species, thus accelerating the amidation
Use of N-trifluoroacetyl-protected amino acid chlorides in peptide coupling reactions with virtually complete preservation of stereochemistry
作者:Paul A Jass、Victor W Rosso、Saibaba Racha、Nachimuthu Soundararajan、John J Venit、Andrew Rusowicz、Shankar Swaminathan、Julia Livshitz、Edward J Delaney
DOI:10.1016/j.tet.2003.02.002
日期:2003.11
The use of protected amino acid chlorides for peptide coupling reactions has long been avoided due to the extensive racemization that commonly occurs during either the acid chloride formation or the coupling reaction itself. Conditions are described which allow N-trifluoroacetyl-protected amino acid chlorides to be generated in high purity and with high retention of stereochemical integrity. Control
由于在酰基氯的形成或偶联反应本身中通常发生广泛的消旋作用,长期以来一直避免使用受保护的氨基酸氯化物进行肽偶联反应。描述了允许以高纯度和高保留的立体化学完整性产生N-三氟乙酰基保护的氨基酸氯化物的条件。温度控制是控制外消旋作用的主要因素,使用Vilsmeier试剂可方便地在低温下快速形成酰氯。当偶联N时,立体化学完整性得到进一步保持-三氟乙酰基酰氯是在Schotten-Baumann条件下与氨基酸酯一起使用的,具体控制pH值,温度和搅动。偶合的第二级速率常数和与外消旋相关的氮杂内酯形成的速率常数分别测量为4260和3.6 L / mol s。这种高速率差异使反应可以在胺酯最少过量的情况下进行,并使其适合于连续加工。描述了优选的偶联条件对一系列氨基酸偶联的适用性。
Synthesis of Novel 1-Oxo-2,3,4-trisubstituted Tetrahydroisoquinoline Derivatives, Bearing Other Heterocyclic Moieties and Comparative Preliminary Study of Anti-Coronavirus Activity of Selected Compounds
作者:Meglena I. Kandinska、Nikola T. Burdzhiev、Diana V. Cheshmedzhieva、Sonia V. Ilieva、Peter P. Grozdanov、Neli Vilhelmova-Ilieva、Nadya Nikolova、Vesela V. Lozanova、Ivanka Nikolova
DOI:10.3390/molecules28031495
日期:——
tetrahydroisoquinoline (THIQ) derivatives bearing other heterocyclicmoieties in their structure were synthesized based on the reaction between homophthalic anhydride and imines. Initial studies were carried out to establish the anti-coronavirus activity of some of the newly obtained THIQ-derivatives against two strains of human coronavirus-229E and OC-43. Their antiviral activity was compared with that of their