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The natural product propindilactone G is a complex Schisandra nortriterpenoid with a unique 5/5/7/6/5 pentacyclic framework.This full paper describes the development of concise biomimetic synthesis of propindilactone G from a known steroid lactone.The key C19-OH intermediate was synthesized via Breslow and Suárez radical remote C-H functionalizations.Wagner-Meerwein rearrangement was subsequently utilized for the expansion of the B ring.To invert the configuration of the C10 tertiary alcohol,an intramolecular peroxide cyclization cata-lyzed by BF3-Et2O was devised.The 5/5 fused lactone system was then assembled in a biomimetic transesterification/oxa-Michael addition sequence.Our work should provide experimental support for the proposed biosynthetic pathway and facilitate investigation of the biological activities of propindilactone G.