Some aspects of siliconmediated reactions

Abstract

PART- I: Cleavage of methyl, methylthiomethyl and benzyl ethers of different alcohols has been achieved with the reag-ent combination of chlorotrimethylsilane and acetic anhydride. An efficient method for the transformation of methylthiomethyl ethers into methoxyethoxymethyl (MEM), methoxymethyl (MOM) and ethoxymethyl (EOM) ethers has also been described. PART - II A: Chlorotrimethylsilane-sodium iodide has been shown to effect the reductive removal of the tert-hydroxy group in the and#945;.and#946;-unsaturated y-tert-hydroxy ketones - an alternative to zinc-acetic acid reduction. PART - II B: Tagitinin c (7) has been converted into 10-deoxy-tagitinin c (18) through the intermediate compound (17) using chlorotrimethylsilane and sodium iodide. PART - III: A direct method of C-isoprenylation of phenols using a combination of chlorotrimethylsilane-sodium iodide and isoprene has been described. PART - IV: Deoxygenation of epoxides with trifluoroacetic acid and sodium iodide has been described which could be a useful alternative to the reagent combination of chlorotrimethyl-silane-sodium iodide. PART - V: Nickel boride generated in situ (from nickel chloride and sodium borohydride) has been found to reductively remove allylic functional groups such as TMS ether, acetate, benzoate etc. Methyl and benzyl ethers are not reductively removed under these conditions.