Alkylation versus trans-silylation of N-methyl-N-trimethylsilylacetamide with ambident electrophiles (chloromethyl)fluorosilanes

Bifunctional silanes ClCH2SiF3 and ClCH2SiF2Me react with N-trimethylsilyl-N-methylacetamide and its tautomer О-trimethylsilyl-N-methylacetimidate as ambident substrates to give the products of trans-silylation N-{[chloro(difluoro)silyl]methyl}-N-methylacetamide and N-{[chloro(fluoro)methylsilyl]methyl}-N-methylacetamide with liberation of Me3SiF, as well as the products of alkylation N-methyl-N-[(trifluorosilyl)methyl]acetamide and N-{[difluoro(methyl)silyl]methyl}-N-methylacetamide with liberation of Me3SiCl. The reaction takes place at room temperature in solvents such as CDCl3, CD3CN or hexane. Under these conditions silane ClCH2SiFMe2 with amide gives only the product of trans-silylation, N-{[chloro(dimethyl)silyl]methyl}-N-methylacetamide. The reactions of trans-silylation and alkylation were monitored and the products and reaction intermediates analyzed by NMR and IR spectroscopy. For all possible reaction routes, quantum-chemical calculations were performed including the analysis of transition states.