Synthesis of 4-Substituted 5-Amino-2-(β-D-ribofuranosyl)thiazoles and 4-Substituted 5-Amino-2-(β-D-ribofuranosyl)selenazoles and Their Respective Conversion into 2-(β-D-Ribofuranosyl)thiazolopyrimidines and 2-(β-D-Ribofuranosyl)selenazolopyrimidines. A New Synthesis ...

Article abstract of DOI:10.1021/jo00210a033

A novel ring closure has been devised to produce fully substituted thiazoles and selenazoles from the condensation of thio- and selenoates with various 2-aminoacetonitrile derivatives.The syntheses of methyl 2,5-anhydroallonothioate (3) and methyl 2,5-anhydroallonoselenoate (4) from methyl 2,5-anhydroallonimidate are described.The condensations of these carboxylates with the appropriate 2-aminoacetonitrile derivatives to give the corresponding 5-amino-2-(β-D-ribofuranosyl)thiazole and -selenazole nucleosides bearing the carboxamide (10 and 13) ethyl carboxylate (11 and 14), and cyano (12) functions at the four positions are reported.Further manipulation of these functionalized thiazoles and selenazoles yielded the corresponding thiazolo- and selenazolo<5,4-d>pyrimidine nucleosides (20, 21, and 22), as well as a thiazolo<5,4-d><1,2,3>triazine nucleoside (23).New syntheses of tiazofurin (1) and selenazofurin (2) via the reductive dediazotization products of ethyl 5-amino-2-(β-D-ribofuranosyl)thiazole-4-carboxylate (11) and ethyl 5-amino-2-(β-D-ribofuranosyl)selenazole-4-carboxylate (14) are also reported.