The reactions of N-substituted 2-(dimethylallyl)aniline compounds with phenylselanyl halides

Cyclization of the carbamate of 2-(dimethylallyl)aniline with phenylselanyl chloride (benzeneselenenyl chloride) gave a 1:1 mixture of a dihydroindole and a tetrahydroquinoline. With phenylselanyl bromide only the dihydroindole was obtained. Addition of methanol to the silica used in the procedure trapped the reaction at the non-cyclized stage forming a 3-methoxy-3-methyl-2-(phenylselanyl)butyl side chain. The sulfonamide of 2-(dimethylallyl)aniline only formed the dihydroindole with phenylselanyl chloride. The corresponding trifluoroacetamide derivative did not form any cyclized product under the same conditions. The dihydroindole could be converted into the corresponding alkene by oxidative removal of the phenylseleno group. 4-Ethoxycarbonyl-2-(3,3-dimethylallyl)aniline cyclized with mercuric nitrate to give, after a reductive workup, a 2,2-dimethyltetrahydroquinoline. The X-ray crystal structures of ethyl N-{2-[3-methoxy-3-methyl-2-(phenylselanyl)butyl] phenyl} carbamate and 2-[1-methyl-1-(phenylselanyl)ethyl]-1-[(4-methylphenyl)sulfonyl]indoline are reported.