Wallis, A. F. A.2014-02-252014-02-251962http://hdl.handle.net/10092/8895http://dx.doi.org/10.26021/6805Enol acetylation of 6-ketocholestanyl acetate by acetic anhydride-sulphuric acid or acetic anhydride-perchloric acid gave the Δ⁵-enol acetate, which on bromination yielded the known 5α-bromo-ketone. Isopropenyl acetate enol acetylation afforded a 1:1 mixture of Δ⁵ - and Δ⁶-isomers, the ratio being determined by bromination of the enol acetate mixture followed by O.R.D. and specific rotation measurements on the mixed 5α- and 7α-bromo-ketone. The 7α-bromo-ketone with pyridine-silver nitrate gave the known 3β-acetoxy-cholesta-6,7-dione together with the 6-keto-Δ⁷-ketone. Dehydrobromination of the 7α-bromo compound by N,N-dimethyl formamide-lithium carbonate gave the 6-keto-Δ-compound in good yield. From O.R.D. measurements the structure of the enol form of 3α-acetoxy-cholesta-6,7-dione has been assigned. A preliminary study has been made of the enol acetylation of both 3βacetoxy-7α-bromo-cholestan-6-one and 3β-acetoxy-cholest-4-en-6-one.dcvalue>enCopyright A. F. A. WallisTheses / Dissertations