马来酸酐 、
dimethyl (1S,8R,9S,10R,12S,13R)-3,6-diacetyloxy-11-benzyl-11-azapentacyclo[6.5.1.02,7.09,13.010,12]tetradeca-2,4,6-triene-10,12-dicarboxylate 生成 dimethyl (1S,2R,3R,4S,8R,9S,10S,11R)-13,16-diacetyloxy-19-benzyl-5,7-dioxo-6-oxa-19-azahexacyclo[9.6.1.13,9.02,10.04,8.012,17]nonadeca-12,14,16-triene-3,9-dicarboxylate