New Stereoselective β-Glycosylation via a Vinyl Oxirane Derived from d-Glucal
摘要:
[reaction: see text] The reaction of the vinyl oxirane 1 derived from D-glucal with a series of O-nucleophiles (alcohols, phenol, and diacetone D-glucose) affords the corresponding 2-unsaturated beta-O-glycosides in a completely stereoselective way (syn 1,4-addition pathway). Epoxide 1 is generated in situ by treatment of the corresponding hydroxy mesylate 2 with t-BuOK in anhydrous benzene.
在与O-,C-,N-和S-亲核试剂的加成反应中,研究了衍生自d-葡糖醛的6- O -Trity1-(1a)和6-(O-苄基)-取代的环氧化物(1b)。通常根据亲核体与环氧乙烷氧配位的能力观察到1,4-区域和β-立体选择性或抗1,2-加成途径。当将TMSN 3或LiN 3用作基于叠氮化物的亲核试剂时,还会观察到1,2-syn加成途径。