Dehydrogenation of 1,2,3,4-tetrahydroquinoline and its related compounds: comparison of Pd/C–ethylene system and activated carbon–O2 system

Dehydrogenation of substituted 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroisoquinoline, and 1,2,3,4-tetrahydrocarbazole proceeded using Pd/C–ethylene system (method A) or activated carbon–O2 system (method B) to give the corresponding heteroaromatic compounds.