Phosphonate versus phosphorane method in the synthesis of higher carbon sugars. Preparation of D-erythro-L-manno-D-gluco-dodecitol

Abstract

Higher sugar (C₁₂ and C₁₃) dialdose precursors 5, 10 and 15 were obtained by a coupling of C₇-phosphorane 1 or C₇-phosphonates 2 and 13 with C₅- or C₆-sugar aldehydes. These compounds were converted into higher dialdoses by (i) stereoselective reduction of a carbonyl group with zinc borohydride followed by (ii) osmylation of the resulting allylic alcohols. One of these derivatives – compound 8a – was converted into D-erythro-L-manno-D-gluco-dodecitol 23 on a 0.5 g scale.