A conceptual extension of the cycloSal‐pronucleotide approach is presented. The characteristic feature of the new cycloSal‐derivatives of the anti‐HIV active nucleoside analogue d4T 1 is the incorporation of an enzymatically cleavable carboxylic ester moiety with the intention to trap the triesters inside cells (”lock‐in”‐concept). CycloSal‐triesters bearing different ester groups in the 3‐or 5‐position
介绍了环Sal-核苷酸方法的概念扩展。抗 HIV 活性核苷类似物 d4T 1 的新环盐衍生物的特征是掺入了可酶切的羧酸酯部分,目的是将三酯捕获在细胞内(“锁定”概念)。描述了在环Sal部分的3-或5-位带有不同酯基的环Sal-三酯。令人惊讶的是,只有乙酰基酯和乙酰丙酸酯在 CEM 细胞提取物中容易裂解,而烷基酯被发现是稳定的。尽管如此,在体外抗 HIV 检测中,大多数化合物实现了胸苷激酶旁路,从而证明它们至少充当核苷酸传递系统。†为了纪念和庆祝 Leroy B. Townsend 教授 70 岁生日。
Twisted Amides as Selective Acylating Agents for Hydroxyl Groups under Neutral Conditions: Models for Activated Peptides during Enzymatic Acyl Transfer Reaction
The highly twisted amide 2 served as a selective acylating agent; for dials under neutral conditions. The reaction of primary-secondary dials with 2 led to the corresponding primary alkyl monopivalates. For dials containing alcoholic and phenolic hydroxyl groups, alcoholic hydroxyl groups were selectively acylated under neutral conditions, whereas, the opposite selectivity was observed under basic conditions, similar to the cases using acyl halides or acid anhydrides. Although 1 and 3 were unreactive to alcohols, 5-10 having substituent groups at C-4 were reactive to alcohols to give the corresponding acetates or benzoates.
Second-GenerationcycloSal-d4TMP Pronucleotides Bearing Esterase-Cleavable Sites — The “Trapping” Concept
An extension of the cycloSal-pronucleotide approach is presented. Attachment of an enzyme-cleavable ester/acylal group to the cycloSal-d4TMP triesters should allow these compounds to be trapped intracellularly after cleavage. The ester/acylal groups were introduced in the 3- or 5-position of the cycloSal ring system, and surprising differences were observed in hydrolysis studies in CEM cell extracts
Selective pivaloylation of Hydroxyl Groups by 3-Pivaloyl-1,3-thiazolidine-2-thione Under Neutral Conditions
作者:Shinji Yamada
DOI:10.1016/0040-4039(92)88169-6
日期:1992.4
conditions, 3-pivaloyl-1,3-thiazolidine-2-thione (PTT) was found to act as a selective pivaloylating reagent for hydroxyl groups. The primary hydroxyl groups of diols containing primary and secondary hydroxyl groups, and the phenolic hydroxyl groups of the diols having alcoholic and phenolic hydroxyl groups were selectively pivaloylated by PTT.