Further observations on the bromination of camphor

Abstract

Recent investigations have shown that direct bromination of (+)-3,3-dibromocamphor provides a mixture of (+)-3,3,8-tribromocamphor, 1,7-dibromo-3,3,4-trimethylnorbornan-2-one, and 1,7-dibromo-4-dibromomethyl-3,3-dimethylnorbornan-2-one. Related studies have shown that (+)-3,9,9-tribromocamphor is a minor product in the known conversion of (+)-3-bromocamphor into (+)-3,9-dibromocamphor. The formation of these products can be rationalised by a general mechanistic scheme which also includes mechanisms for the conversion of (+)-camphor into partially racemic 9-bromocamphor, the acid-catalysed racemisation of camphor, and the isomerisation of (+)-3,9- to (–)-6,9-dibromocamphor.