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。
New Stereoselective β-<i>C</i>-Glycosidation by Uncatalyzed 1,4-Addition of Organolithium Reagents to a Glycal-Derived Vinyl Oxirane
作者:Valeria Di Bussolo、Micaela Caselli、Mauro Pineschi、Paolo Crotti
DOI:10.1021/ol034662f
日期:2003.6.1
[reaction: see text] Epoxide 4 is generated in situ from d-glucal-derived hydroxy mesylate 3. Reaction of epoxide 4 with a series of alkyl- and aryllithium reagents affords 2,3-unsaturated beta-C-glycosides with excellent 1,4-regioselectivity and complete stereoselectivity for the beta-glycoside. Other organometallicreagents demonstrate more complex behavior in their reactions with epoxide 4.