ethyl dodecanoyl carbonate 、
3,18-O-isopropylideneandrographolide 以
二氯甲烷 为溶剂,
反应 18.0h,
以51.2%的产率得到(3S,4E)-4-[2-[(4aR,6aS,7R,10aS,10bR)-Decahydro-3,3,6a,10b-tetramethyl-8-methylene-1H-naphtho[2,1-d][1,3]dioxin-7-yl]ethylidene]tetrahydro-5-oxo-3-furanyl dodecanoate