An expedient synthesis of highly functionalized 1,3-dienes by employing cyclopropenes as C4 units

An efficient method has been described to synthesize dicarbonyl functionalized 1,3-dienes by cleaving the C=C bond of enaminones with cyclopropenes in the presence of a rhodium catalyst. The acetate-substituted cyclopropenes are judiciously chosen as standard C-4 units of 1,3-diene precursors. The reactions are believed to undergo a unique cutting and insertion process, involving a C=C bond cleavage of the enaminone and insertion of a new C(sp(2)) source with the formation of two C-C single bonds. A broad range of substrates can be used to synthesize the corresponding 1,3-dienes under very mild reaction conditions, including low catalyst-loading, ambient temperature, and a neutral reaction solvent.