Selective Wittig olefination in aqueous media for the rapid preparation of unsaturated 7,3-lactone-α-d-xylofuranose derivatives

A highly efficient and rapid protocol for the preparation of the title compounds 1a and 1b from d-glucose derivatives 2a and 2b, respectively, is reported. To this end, highly selective Wittig olefination in aqueous media was developed for the elaboration of α,β-unsaturated acids 5a and 5b, which when treated with DCC, lactonization was accomplished and the title compounds 1a and 1b were obtained in only three sequential steps with overall yields of 85% and 88%, respectively. Additionally, the Z-selectivity was studied by analyzing conformational models of its corresponding oxophosphorinane intermediaries.