[(3S,3aR,4S,6S,6aR,7S,9bS)-6-acetyloxy-3,3a,4-trihydroxy-3,6,9-trimethyl-2,8-dioxo-5,6a,7,9b-tetrahydro-4H-azuleno[4,5-b]furan-7-yl] acetate 、
(S)-(+)-2-methylbutyric anhydride 在
4-二甲氨基吡啶 作用下,
以
四氢呋喃 为溶剂,
反应 1.0h,
以78%的产率得到[(3S,3aR,4S,6S,6aR,7S,9bS)-6,7-diacetyloxy-3,3a-dihydroxy-3,6,9-trimethyl-2,8-dioxo-5,6a,7,9b-tetrahydro-4H-azuleno[4,5-b]furan-4-yl] (2S)-2-methylbutanoate