Mn(III)-Mediated Radical Cyclization for Δ 1 -3-Octalone Synthesis

An efficient and practical synthetic method of Δ 1 -3-octalone, which is a versatile building block for the syntheses of polycyclic compounds, has been developed. The dianion of ethyl acetoacetate reacts with cyclohexene-1-carboxaldehyde (3) to produce the aldol adduct 6, which then undergoes Mn(III)-mediated radical cyclization followed by acetate elimination to give A'-3-octalone 4. A detailed mechanistic insight of Mn(III)-mediated cyclization of 6 has been disclosed.