Patent ID: 7282594

Claim:
A method for the reductive alkylation at the C-3 position of an indole, said method comprising treating the indole with an aldehyde in the presence of a silicon hydride reducing agent selected from the group consisting of tri(C 1 -C 4 alkyl)silane, triphenylsilane, diphenylsilane and phenylmethylsilane, and a Lewis acid selected from the group consisting of salts of boron, aluminium, antimony or a rare earth metal and a halogen or triflate anion, and pentafluorophenylmetallic acids in which the metal is boron, aluminium, antimony or a rare earth metal; and subsequently adding an organic acid to the reaction mixture after the reaction has begun, wherein the organic acid is selected from the group consisting of trifluoroacetic acid, CCl X H 3-X CO 2 H where X is 0-3, p-toluenesulfonic acid, and benzenesulfonic acid.