Synthesis and conformational properties of substituted 1,4,2-oxazasilinanes: low temperature NMR study and quantum chemical calculations

A number of N-substituted 2,2-dimethyl-1,4,2-oxazasilinanes 1 were synthesized and studied by variable temperature dynamic 1H and 13C NMR spectroscopy, room temperature 15N NMR spectroscopy and theoretical calculations at the DFT and MP2 levels of theory. Both the preferred conformers were assigned and the barrier to the ring inversion of the saturated six-membered ring determined. From 1 the corresponding methyl iodide salts were produced, their structure studied by X-ray analysis and found to be in excellent agreement with the results of the theoretical calculations.