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 dihydroindo
le was obtained. Addition of methanol to the silica used in the procedure t
rapped the reaction at the non-cyclized stage forming a 3-methoxy-3-methyl-
2-(phenylselanyl)butyl side chain. The sulfonamide of 2-(dimethylallyl)anil
ine only formed the dihydroindole with phenylselanyl chloride. The correspo
nding trifluoroacetamide derivative did not form any cyclized product under
the same conditions. The dihydroindole could be converted into the corresp
onding alkene by oxidative removal of the phenylseleno group. 4-Ethoxycarbo
nyl-2-(3,3-dimethylallyl)aniline cyclized with mercuric nitrate to give, af
ter a reductive workup, a 2,2-dimethyltetrahydroquinoline. The X-ray crysta
l structures of ethyl N-{2-[3-methoxy-3-methyl-2-(phenylselanyl)butyl] phen
yl} carbamate and 2-[1-methyl-1-(phenylselanyl)ethyl]-1-[(4-methylphenyl)su
lfonyl]indoline are reported.