C-glycofuranosides via tandem Wittig-Michael sequence using a thiazole-armed phosphorane. A route to C-furanosyl α-hydroxy propanals and propionic acids

Abstract

The reactions of 2-thiazolylcarbonylmethylenetriphenylphosphorane with five protected D-furanoses (manno, ribo, arabino, xylo, and lyxo) in refluxing toluene lead to mixtures of α- and β-1-C-(2-thiazolacyl)-glycosides (66 – 93 % overall yield). The β-linked C-glycosides derived from 2,3:5,6-di-O-isopropylidene- D-mannnofuranose was reduced to (R) and (S) akohols which after protection as O-benzyl ethers were transformed to α-alkoxy aldehydes by thiazole-to-formyl conversion; the aldehydes were oxidized to the corresponding α-alkoxy acids.