Fused tetracycles with a benzene or cyclohexadiene core: [2 + 2 + 2] cycloadditions on macrocyclic systems

Abstract

A series of fused tetracycles with a benzene or cyclohexadiene core (2a–h) is satisfactorily prepared by intramolecular [2 + 2 + 2] cycloadditions of triynic and enediynic macrocycles (1a–h) under RhCl(PPh₃)₃ catalysis; the enantioselective cycloaddition of macrocycles1b and 1e gives chiral tetracycles with moderate enantiomeric excess.