乙醇 、
diethyl (1R,3R,7S,8R,9R)-2,2-dichloro-12-oxo-13-oxatetracyclo[7.4.1.01,3.03,7]tetradecane-8,9-dicarboxylate 在
potassium carbonate 作用下,
以65%的产率得到(3aR,4S,5S)-8-Chloro-5-(2-ethoxycarbonyl-ethyl)-7-oxo-1,2,3,3a,4,5,6,7-octahydro-azulene-4,5-dicarboxylic acid diethyl ester