Chemoenzymatic One‐Pot Synthesis of Enantiopure L ‐Arylalanines from Arylaldehydes

Various enantiopure L‐arylalanines can be prepared from the corresponding arylaldehydes in one‐pot fashion by a combination of chemical and enzymatic reactions. The reagents used were (triphenyl‐λ5‐phosphanylidene)ethyl acetate (Wittig reaction), porcine liver esterase (PLE), phenylalanine ammonia lyase (PAL) from parsley and ammonia. As examples the following aryl groups were used: phenyl, 4‐chlorophenyl, 3‐fluorophenyl and thiophen‐2‐yl. The pure L‐enantiomers of phenyl‐, 4‐chlorophenyl‐, 3‐fluorophenyl‐ and thiophen‐2‐ylalanines were obtained after ion‐exchange chromatography in 88, 78, 72 and 91 % yields, respectively, calculated from the arylaldehydes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)