The key intermediate of misoprostol, methyl 7-(3-hydroxy-5-oxocyclopent-1-en-1-yl)-heptanoate was prepared from commercially available suberic acid in 40% yield over five steps. The key step involved a ZnCl₂ catalyzed Friedel-Crafts reaction between furan and 2,9-oxonanedione. Sulfuric acid catalyzed methylation of 8-(furan-2-yl)-8-oxooctanoic acid followed by sequential reduction and ZnCl₂ catalyzed Piancatelli rearrangement resulted in the formation of the key intermediate of misoprostol.

中文翻译：

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实际合成7-（3-羟基-5-氧代环戊-1-烯-1-基）庚酸甲酯

米索前列醇的关键中间体7-（3-羟基-5-氧代环戊-1-烯-1-基）庚酸甲酯是由市售的辛二酸经五个步骤以40％的收率制备的。关键步骤涉及呋喃与2,9-氧代氧化二烯之间的ZnCl ₂催化的Friedel-Crafts反应。硫酸催化8-（呋喃-2-基）-8-氧辛酸的甲基化，然后顺序还原，ZnCl ₂催化的Piancatelli重排导致米索前列醇的关键中间体的形成。