Access to d- and l-Psicose Derivatives via Hydroxy Methylation of Ribono Lactone

Abstract

2,3,5-Tri-O-benzyl- and 2,3,5-tri-O-methyl-d-ribono-γ-lactone were converted with (methoxyethoxymethoxy)methyl and benzyloxy tributylstannane into the corresponding protected d-psicoses as mixtures of anomers in 31%–72% yield. Treatment of 2,3,5-tri-O-methyl-l-ribono-γ-lactone with benzyloxy tributylstannane afforded the corresponding l-psicose derivative as an anomeric mixture in 72% yield. Both methylated psicoses were further converted into 1,2-O-isopropylidene-3,4,6-tri-O-methyl-d- and l-psicofuranosides, the respective α- and β-anomers of which could be separated and characterized.