A new type of cascade reaction: direct conversion of carbonyl compounds and malononitrile into substituted tetracyanocyclopropanes

A new type of chemical cascade reaction was found: the direct formation of cyclopropanes from carbonyl compounds and C–H acid. The action of free halogen or active halogen containing compounds on a mixture of 1 equiv of carbonyl compound and 2 equiv of malononitrile in a basic alcohol solution results in the formation of substituted 1,1,2,2-tetracyanocyclopropanes in 15–80% yield. The latter are well-known precursors for the different bicyclic heterosystems, among them compounds containing a cyclopropane ring and possessing different types of pharmacological activity. Thus, the new, simple and efficient ‘one-pot’ way to substituted tetracyanocyclopropanes in 50–80% yield was found directly from such simple and reasonable starting compounds as aldehydes, or some cyclic ketones, or substituted cyclohexanones and malononitrile.