An Improved Synthesis of (-)-Martinellic Acid via Radical Addition-Cyclization-Elimination Reaction of Chiral Oxime Ether

A concise formal synthesis of (-)-martinellic acid has been accomplished by preparing optically active dipyrroloquinoline as a key synthetic intermediate, which was prepared via the radical addition-cyclization-elimination of oxime ether carrying an unsaturated ester followed by two chemoselective reductions of the carbonyl groups.