A bicyclic silver carboxylate is treated with Br2 and converts to the corresponding bicyclic bromide, with loss of CO2 and AgBr. The following reaction goes through which intermediate?
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Recall that the Hunsdiecker reaction is a radical chain decarboxylative halogenation.
Method: eliminate other intermediates. Carbocation would show rearrangements, not observed. Carbanion needs a base, inconsistent with observed AgBr precipitation. Carbene would need loss of two bonds simultaneously. Only free radical mechanism, accelerated by light and inhibited by radical scavengers, matches observed kinetics.
