甲基(4R)-4-[(3R,5S,7R,8R,9S,10S,12S,13R,14S,17R)-3,7-二乙酰氧基-12-羟基-10,13-二甲基-2,3,4,5,6,7,8,9,11,12,14,15,16,17-十四氢-1H-环戊二烯并[a]菲-17-基]戊酸酯