Titanium-Mediated C–C Coupling of Imidoylstannanes for the Synthesis of Tetraaryl Diimines. Isolation of Titanium Iminoacyl and Ene-diamido Intermediates

Abstract

An efficient one-pot synthesis of tetraaryl α-diimines with various aryl groups via TiCl 4 -mediated C−C coupling of imidoylstannanes followed by dioxygen oxidation in the presence of KF has been described. The protocol is suitable for the synthesis of valuable α-dimines with bulky aryl groups on the nitrogen atoms. The bulky tetraaryl dimine 2a could be prepared on a gram scale and has been utilized for the synthesis of the corresponding N-heterocyclic silylene. The reaction intermediates, an η 2 -iminoacyl titanium trichloride and an αdiamide titanium dichloride, have been isolated and were characterized by single-crystal X-ray diffraction studies.