CuCl-mediated tandem CO insertion and annulation of 1,4-dilithio-1,3-dienes: formation of multiply substituted cyclopentadienones and/or their head-to-head dimers.

Mediated by CuCl, 1,4-dilithio-1,3-dienes reacted with carbon monoxide (CO) to generate multi-substituted cyclopentadienones and/or their head-to-head dimers, via tandem CO insertion and intra/intermolecular cycloaddition of organocopper compounds.