Cetyltrimethylammonium permanganate (CTAP) effects cis -hydroxylation of cyclic vinylsilanes smoothly under mild conditions both in aqueous and nonaqueous solvents. cis -1-Trimethylsilylcycloalkane-1,2-diols 7Ð12 were prepared in good yields. The oxidation occurs at 20¡C and takes a much shorter time in comparison with OsO 4 oxidation reported in the literature.

NOCl adds to cyclic vinylsilanes in a syn manner with NO + bonding to the b-carbon and Cl − to the a-carbon, which is a reversal of the regiochemistry expected from the b-silicon effect. The adducts dimerize to a single diastereomer containing enantiomeric pairs and/or give secondary products on further reaction.

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Acid catalyzed elimination of silanol from the cyclic cis-α,β-dihydroxysilanes 3-8 to cycloalkanones was studied at three different temperatures (298, 313 and 328 K). Silyldiols 3-7 hydrolyzed smoothly, while 8 was resistant to hydrolysis. The observed ease of elimination (reflected in the rate constants) was found to be related to the conformational flexibility of the ring and intramolecular hydrogen bonding. The results have confirmed the requirement of perfect antiperiplanar geometry of the eliminating groups, SiMe 3 and β-OH. The quantitation of the hydrolysis products, the cycloalkanones, was done using the gas chromatographic peak area normalization method using an internal standard. The rate data obtained at three different temperatures were employed to calculate ∆H ‡ , ∆S ‡ , and ∆G ‡ . The rate constants and thermodynamic parameters increase with the ring size. There is an interesting demarcation between these two values for common ring silyldiols and the larger ring silyldiols.

Cycloalkenyltrimethylsilanes add nitrosyl chloride stereo-and regio-selectively. The addition is syn, with chlorine and nitrosyl group adding to C-1 and C-2 respectively. The products dimerize to diazene dioxides, whose stability depends on the conformational flexibility of the ring -the less flexible are more stable. The less stable adducts convert to oximes and further to 1,2-dichloro-1-nitrosocycloalkanes. The adducts can be hydrolysed to α-chloroketones and reduced to β-aminosilanes. Other interesting observations include transposition of keto group in α-chloroketones and X-ray crystal structure of the amide derivative 6f, which reveals -(CO)-HN…H-CH 2 -(CO)-hydrogen contact.