ASYMMETRIC TRANSFORMATION OF ALPHA-AMINO-EPSILON-CAPROLACTAM, A LYSINE PRECURSOR

The lysine precursor a-amino-e-caprolactam (ACL), 1, is rapidly racemized when a solution of its nickel(II) chloride complex is heated at reflux in ethanol in the presence of an excess of 1 and catalytic amounts of ethoxide ion. The complex (DL-ACL)3NiCl2 can be kinetically resolved into its enantiomers by seeding a supersaturated solution with crystals prepared from a single enantiomer, e.g., (L-ACL)3NiCl2-EtOH. When these two processes are combined, a second-order asymmetric transformation can be accomplished. This unique transformation, one of the very few involving enantiomers, has a number of interesting features which are discussed in detail. © 1979, American Chemical Society. All rights reserved.