(tert-butyl)dimethylsilyl]oxy}-7-oxa-bicy clo[2.2.1]heptan-2-one ((+)-5) and its enantiomer (-)-5, obtained readily from the Diets-Alder addition of furan to 1-cyanovinyl acetate. can be converted with high stereoselectivity into 8-oxabicyclo[3.2.1]octane-2,3.4.6,7-pentol derivatives (see 23- 28 in Scheme 2). A precursor of them, (1R,2S,4R,5S,6S,7R,8R)-7-endo-(benzyloxy)-8-exo-hydroxy-3,9-dioxatricycl
对映体纯 (+)-(1S4S,5S 6S)-6-endo-(benzyloxy)-5-exo-[(tert-butyl)dimethylsilyl]oxy}-7-oxa-bicy clo[2.2.1]heptan- 2-one ((+)-5) 及其对映异构体 (-)-5,很容易通过 Diets-Alder 将
呋喃添加到 1-
氰基
乙酸乙烯酯中获得。可以以高立体选择性转化为 8-oxabicyclo[3.2.1]octane-2,3.4.6,7-pentol 衍
生物(参见方案 2 中的 23-28)。它们的前体,(1R,2S,4R,5S,6S,7R,8R)-7-endo-(benzyloxy)-8-exo-hydroxy-3,9-dioxatricycl o[4.2.1.0(2.4)]non -.5-endo-yl benzoate ((-)-19), 转化为 (1R,2R,5S, 6S,7R