Practical method for synthesis of 2,3-disubstituted indole derivatives promoted by β-(benzotriazol-1-yl)allylic O-stannyl ketyl radicals

Treatment of β-aryl-β-(benzotriazol-1-yl)-α-primary alkyl (or aryl)-α,β-unsaturated ketones 1 with n-Bu3SnH (4 equiv) in a catalytic amount of AIBN in PhH at reflux afforded 3-alkyl (or aryl)-2-arylindoles 8 in good yields. However, when tert-butyl group is bonded at α-position, 3-acyl (or aroyl)-2-arylindoles 9 were obtained as major products along with phenanthridines 5 as minor products.