Addition of thiols to silicon-containing. cap alpha. ,. beta. -ethylenic aldimines

The direction of the addition of thiols to ..cap alpha.., ..beta..-ethylenic aldimines is determined by the structure of the reactants: Thiols add to the most basic N-alkyl aldimines in the 1,4 position with the subsequent isomerization of the secondary enamines formed into the products of the formal addition of thiols at the carbon-carbon double bond; weakly basic N-aryl aldimines undergo addition with benzenethiol in the 1,4 position, and the less acidic alkanethiols react at the azomethine group. The 1,4-addition of thiols at the conjugated 1,3-azadiene fragment is determined by the additional polarization of the conjugated double bonds as a result of the donor-acceptor interaction of the reactants with the participation of the unshared electron pair of the nitrogen. The PMR spectra were recorded on a Tesla BS-497 spectrometer (100 MHz). The /sup 13/C NMR spectra of solutions of 4.3 mmoles of the aldimines in 1 ml of solvent were recorded on a Tesla BS-567A spectrometer (25 MHz).