ent-7β,20-epoxy-6α,7α,14α-trihydroxykaurane-1,15-dione 、
1,2-乙二硫醇 在
三氟化硼乙醚 作用下,
以99 mg的产率得到(4a'R,5'S,6'S,6a'R,8'R,9'S,11a'R,11b'S,14'R)-5',6',14'-trihydroxy-4',4',8'-trimethyldecahydrospiro[[1,3]dithiolane-2,1'-[6,11b](epoxymethano)[6a,9]methanocyclohepta[a]naphthalen]-7'(8'H)-one