Thiyl radical mediated racemization of benzylic amines

Thiyl radical mediated reversible H abstraction from the stereogenic center alpha to the nitrogen atom is a mild method to racemize benzylic amines. Owing to the sensitivity of atom-transfer reactions to enthalpic effects, a knowledge of both the S-H and the alpha-C-H bond dissociation energies is fundamental to select the thiol that is appropriate to abstract the hydrogen atom from a given amine. In the absence of experi-mental data, theoretical calculations supply a useful predictive tool. The experiments described here are helpful in delineating the optimal conditions that have to be fulfilled for the racemization. to proceed in a reasonable time in the presence of either a stoichiometric or a catalytic amount of thiol. (c) Wiley-VCH Verlag GmbH & Co.