possibility of a free metaphosphonimidate intermediate. For the MeNH2 reaction, the relative configurations of substrate and product, deduced from their X-ray crystal structures, show the sense of the stereospecificity to be retention of configuration at phosphorus; for the ButNH2 reaction, indirect evidence leads to the same conclusion. Retention of configuration is thought to result from initial base-induced
所述的反应Ñ -phosphinoyl- Ô(PH)(O)-sulfonylhydroxylamine PhMeCH P NHOMs 10与RNH 2(R = Me或卜吨)导致从
磷的苯基的迁移到氮这导致重排产物PhMeCHP( O)(NHPh)NHR。使用富含一种非对映异构体(80:20)或另一种(3:97)的10种样品,与纯净RNH 2的反应具有高度立体特异性,从而排除了游离的偏
亚膦酸酯中间体的可能性。对于MeNH 2反应中,从底物和产物的X射线晶体结构推断出其相对构型,显示出立体特异性的感觉,即保留了
磷的构型。为卜牛逼NH 2反应,间接证据导致了同样的结论。构型的保留被认为是由于最初的碱基诱导的重排导致了膦酰胺
磺酸混合酸酐PhMeCHP(O)(NHPh)OMs的转变,而
磷的构型却发生了反转。然后用RNH 2进行亲核取代,得到所观察到的产物。亲核取代可具有缔合的S N2(P)机理(
磷的构