Cyclohexane compounds. VII. Nucleophilic scission of the stereoisomeric 3-methoxycyclohexene oxides

The mode of scission of cis- and trans-3-methoxycyclohexene oxides by hydrogen chloride, hydrogen bromide, ammonia, acetic acid, and methanol (under both acidic and alkaline conditions) has been examined using vapor-phase chromatography to detect and isolate minor isomers. Approximately 10% of the product from opening of the trans oxide is formed by attack at position-2 with each of these nucleophiles, whereas opening of the cis oxide proceeds exclusively by attack at position-1. The results are interpreted as reflecting very similar transition states for all of these reactions, with differences in product distributions for the two oxides being governed by the inductive effect of the methoxyl group and by steric factors in the corresponding transition states.