REARRANGEMENT OF ALPHA-HYDROXYLAMINO OXIMES TO CYCLIC AMIDOXIMES BY THE ACTION OF SODIUM-BOROHYDRIDE

Treatment of alpha-hydroxylamino and alpha-(O-acetyl)-hydroxylamino ox imes, derived from nitrosochlorides of the monoterpenes alpha-pinene a nd (+)-3-carene, with sodium borohydride in acetonitrile medium result s in rearrangement by ring-expansion and formation of chiral cyclic am idoximes in 35-65% yields. The reaction of alpha-hydroxylamino oximes with the less complex carbon frame (derivatives of cyclohexene, 1-meth ylcyclohexene, isobutylene, 2-butene, beta,beta-dimethylstyrene) does not lead to the ring expansion. Structure elucidation and conformation al analysis of cyclic amidoximes of pinane and carane types are descri bed. Possible reaction pathways are discussed. (C) 1997, Elsevier Scie nce Ltd.