Generation of N,N-disubstituted iminium salts by application of silane reagents

(Dialkylamino)trimethylsilanes, halotrimethylsilanes and trimethylsilyl triflate proved to be superior reagents for a convenient access to the title compounds in an aprotic medium. In most cases, the co-formation of silylethers or disiloxanes acts as driving force. A comprehensive overview on this field, including the latest findings, is given and the significant mechanistic relationships are illuminated. The three component synthesis starting from carbonyl compounds (Scheme 3) and the two component synthesis ("latent" three component synthesis) starting from alpha-chloroethers (Schemes 16, 19) hold a central position. The latter method offers special advantage for the entrance into the multifunctional series, as shown by the first synthesis of vinylogous Viehe sails as preparatively useful C-3-building blocks (Schemes 17, 22, 23). As an aim, this report should stimulate further progress in these areas.