A process for forming 4-ketocyclopentene and substituted 4-ketocyclopentene compounds starting from the corresponding 1-carbohydrocarbyloxy-2-keto-4-hydroxy-5-cyclopentene by reduction followed by decarboxylation using zinc dichloride or zinc dibromide. The ketone may thereafter be converted to a cyclopentadiene compound by reducing the ketone to form an alcohol, replacing the hydroxyl functionality of the alcohol under substitution conditions with a leaving group, and deprotonating the resulting product under base induced elimination conditions to form the cyclopentadiene compound. Alternatively functionalized cyclopentadienyl compounds can be produced without isolation of an unsubstituted cyclopentadienyl compound by combining the elimination and deprotonation steps with a replacement step in a single unit operation.
从相应的1-碳氢烷氧基-2-酮-
4-羟基-5-
环戊烯开始,通过还原后脱羧,使用
氯化锌或
溴化锌形成4-酮
环戊烯和取代的4-酮
环戊烯化合物的过程。然后,可以通过将酮还原形成醇,用取代条件下的离去基取代醇的羟基官能团,并在碱诱导的消除条件下去质子化所得产物以形成
环戊二烯化合物。或者,可以通过将消除和去质子化步骤与替换步骤结合在单个单元操作中,而无需分离未取代的
环戊二烯基化合物来生产功能化的
环戊二烯基化合物。