Selectivity in Ring‐Closing Metathesis: Synthesis of Propellanes and Angular Aza‐tricycles

Abstract

AbstractSeveral naturally occurring alkaloids contain quaternary carbon centers attached to a nitrogen atom. An efficient synthetic protocol has been developed to assemble indoline‐fused propellanes over aza‐tricyclic carbazole derivatives via a selective ring‐closing metathesis employing Grubbs’ first‐generation catalyst. Electronic factors seem to play a critical role in the outcomes. The structure of propellanes and angular aza‐tricyclic compounds are confirmed by catalytic hydrogenation sequence. To expand the synthetic utility of these propellanes and aza‐tricycles, Suzuki‐Miyaura cross‐coupling reaction has been employed to generate functionalized polycycles. Fourteen ruthenium carbene catalysts are examined to synthesize propellanes and aza‐tricycles.magnified image