乙酸酐 、
3α-angeloyloxy-18β-glucopyranosyloxy-ent-labd-8(17),13-dien-15,16-olide 在
4-二甲氨基吡啶 作用下,
以
氯仿 为溶剂,
生成 (Z)-2-Methyl-but-2-enoic acid (1S,2R,4aS,5R,8aS)-1,4a-dimethyl-6-methylene-5-[2-(5-oxo-2,5-dihydro-furan-3-yl)-ethyl]-1-((3R,4S,5R,6R)-3,4,5-triacetoxy-6-acetoxymethyl-tetrahydro-pyran-2-yloxymethyl)-decahydro-naphthalen-2-yl ester