Ursonic acid 11,12-dehydro-13,28-lactone 在
吡啶 、
盐酸羟胺 作用下,
以
异丙醇 为溶剂,
以86 %的产率得到(6aR,6bS,8aS,11R,12S,12aR,12bS,14aR,14bS,Z)-3-(hydroxyimino)-4,4,6a,6b,11,12,14b-heptamethyl-2,3,4,4a,5,6,6a,6b,7,8,10,11,12,12a,14a,14b-hexadecahydro-1H,9H-12b,8a-(epoxymethano)picen-16-one