SODIUM-BOROHYDRIDE IN AN ACETONITRILE MEDIUM - AN EFFICIENT REAGENT FOR REDUCTIVE BECKMANN TYPE FRAGMENTATION OF ALPHA-AMINO OXIMES

When treated with sodium borohydride in boiling acetonitrile, alpha-am ino oximes are transformed to the corresponding omega-amino nitriles i n 31-87% yield. Easily available alpha-amino oximes with cyclohexane, methylcyclohaxene, p-menthane, carane, pinane, and caryophyllane carbo n skeletons are tested. The reaction was found to proceed only in an a liphatic nitrile medium; the specific role of a nitrile is discussed. Beckmann synchronous mechanism was confirmed for the fragmentation sta ge followed by reduction of the intermediate immonium salt. (C) 1997, Elsevier Science Ltd.