Hypohalogenation of functionally substituted acetylenic norbornenes

Hypohalogenation of norbornenes containing a triple bond and various functional groups in the side chain was performed using mixtures of aqueous solutions of hydrochloric or hydrobromic acid (or sodium or potassium bromide) and hydrogen peroxide. The reaction was found to involve addition of electrophilic reagent generated in situ (HOBr or HOCl) at the endocyclic double bond with formation of the corresponding halohydrins. The latter underwent dehydrohalogenation by the action of alklai to give exo -5,6-epoxybicyclo[2.2.1]-heptane derivatives in high yields. Kinetic relations holding in the hypobromination process were established, and the initial rates and activation parameters were calculated.