Synthesis and Stereochemistry of Substituted 1,3-Dioxa-2-silacyclohexanes: VII. Synthesis and Stereochemistry of Substituted 2-Vinyl-2-methyl-1,3-dioxa-2-silacyclohexanes

The stereochemistry of substituted 2-vinyl-2-methyl-1,3-dioxa-2-silacyclohexanes was studied by ^1Hand ^13C NMR spectroscopy. The configurational and conformational assignment of a mixture of 2-vinyl-2,4-dimethyl-1,3-dioxa-2-silacyclohexane diastereomers with various ratios of the cis and trans forms was made. The molecules of both conformers occur chiefly in the chair conformartion with equatorial location of the methyl group at the C⁴ atom. The experimental data were confirmed by AM1 and MM+ optimization of the molecular geometry.     

Homolytic and Conjugate Addition of Thiols to 2,4-Dimethyl-2-vinyl-1,3-dioxa-2-silacyclohexane

Homolytic reaction of 1-propane- and 1-pentanethiols to 2,4-dimethyl-2-vinyl-1,3-dioxa-2-silacyclohexane, initiated by di-tert-butyl peroxide at 130°C, yields a mixture of isomeric sulfides (95%) as a result of addition at the - and -positions of the vinyl group. Conjugate addition of alkanethiols in the presence of the corresponding sodium thiolate at 100°C gives 10% of the same - and -regioisomeric sulfides at a ratio of 1:20.