Reaction of N-nitroaryl-1,2,3,4-tetrahydroisoquinoline derivatives with oxygen

Heating N-4′-methyl-2′-nitrophenyl-1,2,3,4-tetrahydroisoquinoline ( 1 ) in the presence of oxygen gave both products derived from cleavage of the C8a? Cl bond and oxidation at the 1-position. Under similar conditions N-4′-nitrophenyl-1,2,3,4-tetrahydroisoquinoline ( 4 ) gave only the oxidation product.