乙酸酐 、
Acetic acid (3S,3aR,4aS,6aS,8R,10aR,10bS)-3-formyl-3,7,7,10a-tetramethyl-dodecahydro-4-oxa-cyclopropa[j]phenanthren-8-yl ester 在
三氟化硼乙醚 作用下,
以80%的产率得到Acetic acid (2R,4aR,4bS,7S,10aS)-8-acetoxy-7-formyl-1,1,4a,7-tetramethyl-1,2,3,4,4a,4b,5,6,7,9,10,10a-dodecahydro-phenanthren-2-yl ester