Preparation of N,N,N′-tris(trimethylsilyl)amidines; a convenient route to unsubstituted amidines

Abstract

The tris(trimethylsilyl)amidines RC(NSiMe 3)N(SiMe 3) 2 (R  C 6H 5, p-CH 3C 6-H 4, p-ClC 6H 4, p-MeOC 6H 4, p-Me 2NC 6H 4, p-CF 3C 6H 4, p-C 6H 5C 6H 4 and CF 3) are prepared by the reaction of the respective nitriles with (Me 3Si) 2NLi·OEt 2 in ether to give intermediates RC(NLi)N(SiMe 3) 2. Heating these intermediates with ClSiMe 3 in toluene affords the products, which are isolated by vacuum distillation, in high yield. With 1,4-dicyanobenzene, two equivalents of reagents affords the per(trimethylsilyl)-1,4-diamidine. Hydrolysis of the intermediates with 6 N ethanolic HCl affords the unsubstituted amidine hydrochlorides RC(NH)NH 2·HCl (R  C 6-H 5, p-MeOCh 6H 4, p-ClC 6H 4, p-O 2NC 6H 4) in high yield.