Fragmentation of carbohydrate anomeric alkoxy radicals. synthesis of polyhydroxy piperidines and pyrrolidines related to carbohydrates

Abstract

Imino sugars of the piperidine and pyrrolidine types can be specifically obtained when protected 5-amino-5-deoxyfuranopentoses, 5-amino-5-deoxyfuranohexoses, 6-amino-6-deoxyfuranohexoses, and 6-amino-6-deoxypyranohexoses undergo a tandem alkoxy radical β-fragmentation−intramolecular cyclization reaction. The reaction is promoted by the system: iodosylbenzene−iodine under mild conditions. The tert-butoxycarbonyl, benzyloxycarbonyl, and diphenylphosphinoyl radicals have been studied as amino-protecting groups. Using this methodology, polyhydroxylated pyrrolidines of the d-erythrofuranoses 34 and 35, d-threofuranose 36, l-xylofuranose 42, and d-arabinofuranose 43 series and polyhydroxylated piperidines of the d-arabinopyranose type 37 and 38 were obtained.