Halogenated terpenoids. VIII. The halogenation of some axial α-Bromo-p-menthanones. Boat conformers of halogenated cyclohexanones

Abstract

The structures of some halogenated p-menthan-2-ones and p-menthan-3- ones are determined. Some cyclohexanones with α-axial bromine and α?- equatorial bromine substituents exist in a boat conformation provided an additional attractive halogen→carbonyl interaction is available to stabilize the boat through a five-membered bridging ring. Some profound differences in the conformations of bromo- and chloro-cyclohexanones are noted. The α?-bromination of α-bromocyclohexanones is discussed. The configurations of the new compounds are determined chemically and the conformations are determined chiefly by p.m.r. spectroscopy.