AN EFFICIENT ASYMMETRIC-SYNTHESIS OF (2S,3S)-3-TRIFLUOROMETHYLPYROGLUTAMIC ACID

The stereochemical outcome of the Michael reaction between ethyl 4,4,4 -trifluorocrotonate and a Ni(ID complex of the Schiff base of glycine with (S)-o-[N-(N-benzylprolyl)amino]benzophenone was found to be subje cted to kinetic and thermodynamic control. Thus, under kinetically con trolled conditions high values of diastereo-selectivity, up to 94% de, allowing for an efficient asymmetric synthesis of (2S,3S)-3-trifluoro methylpyroglutamic acid, could be obtained, while the thermodynamicall y controlled stereoselectivity is rather modest (54-60% de). (C) 1997 Elsevier Science Ltd.