An Intermolecular Double [2+2] Cyclodimerization of a Tetraalkyne

摘要

Cobalt(I)-mediated [2+2] cycloadditions of alkynes are known to give stable organometallic compounds which contain an η4-cyclobutadiene fragment. Gleiter and co-workers exploited this chemistry in the synthesis of their trinuclear beltene system. The research group of Vollhardt used cobalt to generate fused six- and four-membered ring systems discussed as models for non-delocalized benzene, that is, cyclohexatriene. Bunz and co-workers constructed a series of highly alkynated carbon-rich derivatives.