Synthesis of 1′-(3-dimethylaminopropyl)-2′-substituted spiro[cycloalkane-1,3′indolines]

Abstract

Reactivity of the CN bond in spiro[cycloalkane-1,3′-3H-indoles] has been analysed. Indolines were obtained in practically quantitative yield using organomagnesium reagents in the presence of copper(i) chloride in toluene at 120 °C. On the basis of an analysis of the reaction products and the e.s.r. spectra, a mechanistic pattern could be proposed. N-Alkylation of 2′-substituted spiro[cycloalkane-1,3′-indolines] has been carried out using as alkylating agent 3-chloro-N,N-dimethylpropionamide, which gave the 1′-(3-dimethylaminopropyl)-2′-substituted spiro[cycloalkane-1,3′-indolines] in good yield on reduction with LiAlH₄.