The Preparation of a Hexacyclic Intermediate for the Synthesis of Strychnos Alkaloids

Abstract

The hexacyclic ring system, indolizino[7,8,8a,1-bcd]-pyrido [1,2,3-lm]carbazolone 10 has been synthesized in nine steps from the pyrido[3,2,1-jk]carbazolylethanal 3. Key steps include the selective reduction of aldchyde 3, the stereoselective introduction of an allyl unit via the Sakurai reaction and the ozonolysis/dehydrative cyclization to afford bridgehead enamine 10.