The stereochemistry of 1,3-elimination in a locked norbornyl system, endo , endo -5,6-dideuterio- exo -2-bromonorbornane-1-carboxylic acid methyl ester

A fractional loss of 90% of one deuterium in the formation of deuterionorticyclene-1-carboxylic acid methyl ester (4a) on solvolysis of endo,endo-5,6-dideuterio-exo-2-bromonorbornane-1-carboxylic acid methyl ester (1b) is consistent with at least a 15 : 1 preference for cleavage of an endo- over exo-C–H bond at C-6.