An Unexpected Oxidation in the Generation of Cyclopenta[c]piperidines by Ring-Closing Metathesis

Abstract

Ring-closing metathesis reaction of dienes A (n= 1, R= CO2R') leads to fused cyclopentenones C instead of the expected cyclopentene derivatives B. RCM reaction of the other dienes A takes place satisfactorily, affording the expected fused cycloalkene derivatives B. Cyclohexene B (n= 2, R= CO2R') also undergoes oxidation to the corresponding cyclohexenone C.