A novel synthesis of tricyclic-fused hydrindene–azetidinone compounds by sequential Mn(III)-promoted 4-exo-trig cyclization/radical aromatic substitution

The 2-acyl-N-(2,2-diphenyl-1-ethenyl)-N-alkylacetamides reacted with excess Mn(III) affording tricyclic fused hydrindene-azetidinones in good yields, through a 4-exo-trig radical cyclization process, and further ring closure of the azetidinone via radical aromatic substitution.