D:A-friedo-18β-lup-19-en-3-one was transformed into D:B-Friedo-18β,19αH-lup-5-en-3β-ol by two routes, 1) bromination-dehydrobromination of an enol benzoate of D:A-friedo-18β,19αH-lupan-3-one and 2) BF3·Et2O-catalyzed backbone rearrangement of 3β,4β-epoxy-D:A-friedo-18β, 19αH-lupane. The 18βH,19αH-configuration in these D:A- and D:B-friedo-type lupane derivatives was determined by means of X-ray diffraction for a 3α,4α-epoxide derived from D:A-friedo-18β,19αH-lupan-3β-ol. The synthetic D:B-friedo-18β,19βH-lup-5-en-3β-ol was found to be not identical with guimarenol isolated from Ceropegia dichotoma.
D:A-friedo-18β-lup-19-en-3-one通过两种途径转化为D:B-Friedo-18β,19αH-lup-5-en-3β-ol,1)D:A-friedo-18β,19αH-lupan-3-one的烯醇
苯甲酸的
溴化-脱氢
溴化,2)3β,4β-环氧-D:A-friedo-18β,19αH-lupane的
BF3·Et2O催化骨架重排。这些D:A-和D:B-friedo-型lupane衍
生物中的18βH,19αH-构型是通过X射线衍射法从D:A-friedo-18β,19αH-lupan-3β-ol衍生的3α,4α-环氧物中确定的。合成的D:B-friedo-18β,19βH-lup-5-en-3β-ol与从Ceropegia dichotoma中分离出的guimarenol并不相同。