A cascade radical-mediated macrocyclisation-transannulation approach to oestrogen steroids

摘要

A new approach to ring A aromatic steroids, based on cascade 13-endo-trig/dig macrocyclisations followed by sequential 5-exo-trig and 6-exo-trig transannulations, exemplified in the syntheses of the cis, anti, trans tetracycle 9 and the trans, syn tetracycle 13 from the ortho-substituted aryl polyen(yne) precursors, 8 and 12 respectively, is described.