The Dieckmann Condensation

Schaefer, John P.; Bloomfield, Jordan J.


The Dieckman condensation is an acetoacetic ester condensation in which a dicarboxylic ester is cyclized to a beta-ketonic ester through the action of a base. The dicarboxylic ester must have at least one alpha-hydrogen atom and the carbalkoxy groups must be situated that cyclization will result in a 4-membered ring or larger ring. Discovery and development of the reaction are generally credited to Dieckmann, who found that heating an adipic or a pimelic ester with sodium and a trace alcohol led to cyclization with formation of a cyclopentanone or a cyclohexanone. The Dieckmann condensation has proved useful for the preparation of a variety of carbocyclic and heterocyclic ketones and has been extended to the synthesis of 7 and 8-membered rings.