Interaction of 1-methoxycyclohexene-2 and aqueous N-bromosuccinimide gave a mixture of stereoisomeric bromohydrins, which, on treatment with aqueous sodium hydroxide, furnished 1~-methoxy-2a,3a-epoxycyclohexane (I) and la-methoxy-2a,3a-epoxycyclohexane (11) in the ratio 3: 1. The mixture from the N-haloimide-olefin reaction was separated by preparative vapor phase chromatography into three isomeric bromohydrins, la-methoxy-2a-hydroxy-3B-bromocyclohexane (IV), la-methoxy-2a-bromo-3B-hydroxycyclohexane (V), and la-methoxy-2B-bromo-3a-hydroxycyclohexane (VI) in the relative proportions 1:10:4. The 3-bromo isomer IV was identified by comparison with an authentic specimen prepared by the action of hydrobromic acid on the oxide 11. Compounds V and VI were shown to have the indicated structures by deetherification to the corresponding bromodiols VII and VIII in high yield, followed by debromination of the latter to trafzs-and cis-1,3-cyclohexanediol respectively. T h e product distribution is considered in relation to the intervention of electronic and steric factors in a possible mechanism suggested for the reaction between aqueous N-bron~osuccinimide and 1-methoxycyclohewne-2.Several years ago (1) we reported that the action of hydrobroinic acid on the stereoisoineric 1-methoxy-2,3-epoxycyclohexanes I and I1 led t o the formation of la-methoxy-2P-hydroxy-3a-bromocyclohexane (111) and 1a-n~ethoxy-2a-hydroxy-3~-broinocyclohexane (IV) respectively. The structures of these substances were established by a variety of chemical means (1) because we wished t o determine their relationship t o the mixture of bromohydrins resulting froin the action of aqueous N-broinosuccinimide upon l-inethoxycyclohexene-2. The latter bromohydrin mixture furnishes the oxides I and I1 in the ratioof 3 : l on treatment with aqueous sodium hydroxide and since 1,2-halohydrin t o oxide conversions involve a trans ring closure (3,4), it is apparent that the trans oxide I could have arisen from either or both of la-methoxy-2P-hydroxy-3a-brornocyclohexane (111) and la-methoxy-2a-bromo-3p-hydroxycyclohexane (V). Likewise the cis-oxide I1 wouId be formed if the mixture contained either la-methoxy-2a-hydroxy-3P-bromocyclol~exane (IV) or 1a-t~~ethoxy-2~-bromo-3a-hydroxycyclohexane (VI) or both. The present coinrnunication describes the manner in which the conlposition of the bronlohydrin mixture from the olefin-N-haloirnide reaction was determined and provides an unequivocal proof of structure for 1a-methoxy-2a-bromo-3~-hydroxycyclohexane (V) and la-n1etlloxy-2P-brorno-3a-h~.droxycyclohexane (VI).Attempts t o separate the components of the bromohydrin mixture by fractional distillation i n vacz~o and by coluinn chronlatography on alumina were unsuccessful. We therefore explored chemical separations based upon the forillation of crystalline derivatives. In this connection, the possible utility of acetate, p-toluenesulfonate, 2,4-dinitrobenzenesulfenate, dichloroacetate, 3-nitrophthalate, phenylurethane, and naphthylurethane derivatives was examine...
