Electroreductive Cyclopropylcarbonylation of Aromatic Ketones and Their Schiff Bases

Article abstract of DOI:10.1021/jo00341a029

Mono- and dicyclopropylcarbonyl derivatives have been obtained by electroreduction of fluorenone, benzophenone, fluorenone anil, and benzophenone anil in the presence of 1 equiv of 4-bromo(or chloro)butyryl chloride (1a or 1b).The electrolyses are carried out in DMF or MeCN according to two methods.In method A, 1a (or 1b) is added dropwise during the electrolysis.In method B, the total amount of 1a (or 1b) is added at the beginning of the experiment.The electrogenerated bases which are necessary to perform the cyclopropylcarbonylation reactions are either theradical anions of the depolarizers or their acylated anions.The distribution of the compounds and their yields, which are moderate, depend on two main factors which are the method applied and the solvent.It is shown that the properties of acid chlorides 1a and 1b differ in DMF and MeCN.The highest yields of cyclopropyl derivatives are reached in MeCN when method B is applied.However, in this solvent the acylation reaction is less specifically orientated than in DMF, and unexpected propionitrile derivatives are isolated.In the case of the anils, results of chemical reduction by alkali metals and electrochemical reduction are compared.