RADICAL REACTIONS LEADING TO SUBSTITUTED PYROGLUTAMATES

The Bu3SnH mediated cyclisation of a serine-derived dehydroalanine was shown to provide an efficient approach to a protected 4-phenylpyroglu tamate which was elaborated to 4-phenylglutamic acid in good yield. Cy clisation reactions of this type were shown to proceed via an intermed iate captodative radical which could be trapped intermolecularly using an alkene e.g. styrene or methyl methacrylate. This method has potent ial for the synthesis of various 4- and/or 2-substituted glutamic acid s. (C) 1998 Elsevier Science Ltd. All rights reserved.