Synthesis of N-Alkylated Indolines and Indoles from Indoline and Aliphatic Ketones

A survey of redox aminations of indoline with aliphatic ketones using bismuth nitrate as catalyst is described. A reaction of an equivalent amount of indoline and aliphatic cyclic and acyclic ketones provides a mixture of excessive alkylated indole derivatives over typically redox isomerization and reductive alkylation pathways while using of the five equivalent of indoline provides N-alkylated indolines as a reductive alkylation product. The desired N-alkyl indoles from the oxidation of N-alkyl indolines were obtained in excellent yields.