The Reductive Cyclization of 1-Methyl-3-aminoalkyloxindoles with Lithium aluminum Hydride.

Lithium aluminum hydride also was found to be effective as the Ladenburg method for the reductive cyclization of 3-(2-aminoethyl)-, 3-(3-aminopropyl)-1, 3-dimethyl oxindole (IVa and IVc) and their N-methyl derivatives (IVb, IVd) to pyrrolo (and pyrido) [2, 3-b] indole derivatives (Va-Vd). With a little excess of lithium aluminum hydride IVd gave a indoline derivative (VIII) together with the cyclized base (Vd) though the latter of which could not be cleaved by lithium aluminum hydride even under more strenuous condition.