Silylation and alkylation of thioamide dianions ofN-arylmethyl secondary thioamides, and reduction of the resulting thioamides leading to secondary and primary amines

Abstract

This paper is dedicated to Professor Juzo Nakayama on the occasion of his 65th birthday and retirement.N -arylmethyl aromatic thioamides were reacted with n-BuLi (2 equivalents), and then treated with silylpropyl chloride and silyl chlorides. As a result, these electrophiles were introduced to the carbon atom adjacent to the nitrogen atom of thioamides via thioamide dianions. The efficiency of the reaction was largely influenced by the substituents on the aromatic ring of thioamides. The reaction of thioamides having pyridyl groups was not always successful and depended on the position of the nitrogen atom of these groups. Reduction of the resulting thioamides with LiAlH 4 proceeded smoothly to give the corresponding secondary N -1-silylarylmethyl amines in good yields. In contrast, the reduction of thioamides bearing pyridyl groups gave complex mixtures. In these cases, the use of DIBAH successfully gave the desired secondary amines.

Transformation of RN=CHPh to R(R′3Si)NCH2Ph in the Catalytic Desulfurization of Secondary Thioamide with R′3SiH Promoted by an Iron Complex

“…Most chemicals were commercially available except thioamides 2 , 3 , and 4 . Thioamides 2 and 4 were synthesized according to the literature methods . IR spectra were recorded on a Perkin‐Elmer Spectrum One spectrometer.…”