1H NMR Investigation of Si-alkylsubstituted 1,3,5-Trisilacyclohexanes

Abstract; Alkylsubstituted derivatives of 1,3,5-trisilacyclo-hexane have been prepared and their 1H NMR spectra recorded and analysed. For the compound series 1-mono-. cis-1,3-di- and cis-cis-1,3,5-tri-alkylated derivatives (alkyl=Me, Et. i-Pr and t-Bu) it is found that the conformational preference for an equatorial position of the substituents in the chair form is considerably less than for cyclohexane derivatives. In the compound series trans-1,3-di- and cis-trans-1,3,5-tri-alkylated derivatives the t-butyl group is found to behave uniqually by forcing the ring to escape into the twist-boat form. Each kind of substituent is found to have a characteristic effect on the chemical shift values of the ring protons.