摘要：

In order to determine the extent to which the occurrence of the Wagner-Meerwein rearrangement is influenced by the participation of a carboxyl group either α or β to the carbon carrying a replaceable bromine the reactions of 2-bromodibenzo-[2.2.2] bicycloctadiene-2-carboxylie acid and 3-bromodibenzo[2.2.2]bicycloctadiene-cis- and trans-2-carboxylic acids with hydroxide, bicarbonate and silver ion have been examined. The highly hindered nature of the bridge carbons in this bicyclic system is further demonstrated by the absence of intermolecular substitutions, and dehalogenative decarboxylation and β-lactone formation are found to be inhibited for the 3-bromo-trans-isomer owing to the peculiar geometry of the system which results in a non-coplanar conformation for the reacting centers. The preference for trans-dehydrohalogenation appears to be more complex than in simple systems due to steric interaction between bromine and the carboxyl group which produces a conformation less unfavorable for trans- than for cis-dehydrohalogenation. A further example of cis-dehalogenative decarboxylation is described, and hindrance to other modes of decomposition permits more extensive occurrence of the Wagner-Meerwein rearrangement.

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