Application de la réaction de Wittig à la synthèse de dérivés de bromoénosuloses et d'esters bromoénuroniques. Note de laboratoire

Abstract

Use of the Winig reaction for the synthesis of derivatives of bromoenosuloses and bromoenuronic esters SummaryTreatment of 3-0-benzyl (or 3-0-methyl)-1,2-O-isopropy~idene-u-~-xylo-pentodialdo-1,4-furanoses (2 or 1) with acetylbromomethylidenetriphenylphosphorane (3), benzoylbromomethylidenetriphenylphosphorane (4) or bromoethoxycarbonylmethylidenetriphenylphosphorane (5) gave in good to excellent yields the expected enose (6-11). In all cases but one (8 where some 10% of the E-isomer was formed) the reaction led to the exclusive formation of the 2-isomer whose configuration was established by NMR.