Model Syntheses of Thiazolidine Nucleoside Analogues
摘要:
The syntheses of racemic thiazolidinyl thymine and cytosine derivatives 6a and 6b, and 10a and 10b, prototypes of a novel family of heterosubstituted nucleosides, have been achieved from rhodanine (3) or thiazolidine (7) by a short sequence of steps. The key reaction involved efficient coupling of silylated thymine and cytosine to N-Boc-protected 4- and 5-acetoxythiazolidines, 5 and 9, assisted by tert-butyldimethylsilyl trifluoromethanesulfonate.
The syntheses of racemic thiazolidinyl thymine and cytosine derivatives 6a and 6b, and 10a and 10b, prototypes of a novel family of heterosubstituted nucleosides, have been achieved from rhodanine (3) or thiazolidine (7) by a short sequence of steps. The key reaction involved efficient coupling of silylated thymine and cytosine to N-Boc-protected 4- and 5-acetoxythiazolidines, 5 and 9, assisted by tert-butyldimethylsilyl trifluoromethanesulfonate.
Substrate acidities and conversion times for reactions of amides with di-tert-butyl bicarbonate
作者:Marvin M. Hansen、Allen R. Harkness、D. Scott Coffey、Frederick G. Bordwell、Yongyu Zhao
DOI:10.1016/0040-4039(95)01931-7
日期:1995.12
The conversion time tor 4-dimethylaminopyndine catalysed reaction of amides with di-tert-butyl dicarbonate varies dramatically with substrateacidity. The pKa's in DMSO of some amides are determined to support correlation of reactivity with substrateacidity. Particularly acidic substrates, such as 4-thiazolidinone, readily react with a variety of dialkyl dicarbonates. Less acidic substrates react