Oxidation by cobalt(III) acetate. Part 7. Regioselective synthesis of substituted cyclohexenyl acetates

Abstract

The oxidation of alkylcyclohexenes with cobalt(III) acetate has been studied in acetic acid under nitrogen. 1-Alkylcyclohexenes gave exclusively the corresponding 3-acetoxy-1-alkylcyclohexenes in good yields. Similarly, 3- and 4-methylcyclohexene afforded 3-acetoxy-6- and -5-methylcyclohexene, respectively, in surprising high selectivities. In all cases, the position α to the alkyl group was completely or largely insensitive to Co^III. The results can be explained in terms of steric hindrance of the alkyl group which limits the attack of Co^III at a hindered site.