The reaction of α-chloronitrosocyclohexane with allylzinc reagents in THF selectively provides O-allylcyclohexanone oximes in very good yields in an ene type reaction followed by zinc halide elimination. N-Allyl hydroxylamines are formed as minor products via N-allyl nitrones when a nonpolar solvent, e.g. toluene, is employed. In both cases complete allylic transposition with respect to the allylic organozinc reagent is observed. Compared to non-metalated allyl compounds, which give N-allyl nitrones upon reaction with α-chloronitroso compounds, the use of zinc as hydrogen equivalent in an ene type reaction displays a drastic change of reactivity.
α-
氯亚
硝基环己烷与烯丙基
锌试剂在THF中反应,选择性地以很高的产率提供O-烯丙基
环己酮肟,这是一种ene型反应,随后发生
锌卤化物消除。当使用非极性溶剂(例如
甲苯)时,会形成N-烯丙基羟
肟作为少量产物,产物的形成途径是通过N-烯丙基亚硝酮。在这两种情况下,完全的烯丙基转位相对于烯丙基
有机锌试剂被观察到。与非
金属化的烯丙基化合物相比,后者在与α-
氯亚
硝基化合物反应时形成N-烯丙基亚硝酮,使用
锌作为氢的等价物在ene型反应中显示出反应性发生了剧烈变化。