Studies on the Enantioselective Synthesis of Carbazolones as Intermediates in Aspidosperma and Kopsia Alkaloid Synthesis

Two strategies for the assembly of homochiral carbazolones have been investigated. The first exploited desymmetrisation of 1,3-cyclohexadione derivatives however this failed to deliver satisfactory outcomes. An orthogonal route exploiting palladium catalysed decarboxylative allylation of racemic carbazolone beta-ketoesters has been developed. Herein we report full details on the development of this reaction and clarify apparent discrepancies between our preliminary reports and those of Shao.