(3aR,6aS)-3abeta,5,6,7abeta,7bbeta,8a,8bbeta,8calpha-八氢-4beta-乙酰氧基-6beta-羟基-6,8abeta-二甲基-3-亚甲基-4H-二环氧乙烷并[1,8a:2,3]薁并[4,5-b]呋喃-2(3H)-酮 生成 [(1S,2R,4S,5R,6R,9S,10S,11R,13S,14R)-2-hydroxy-2,6,11-trimethyl-7-oxo-8,12,15-trioxapentacyclo[8.5.0.01,14.05,9.011,13]pentadecan-4-yl] acetate