Methylenethioxophosphorane (thiophosphene) intermediates in the reactions of diphenylmethylphosphonamidothioic chlorides with amines. Differences between the elimination–addition mechanisms of nucleophilic substitution for PS and PO substrates
作者:Martin J. P. Harger
DOI:10.1039/b109944m
日期:2002.2.25
In reactions with R2NH (R = Me or Et) in CHCl3 the PS substrate Ph2CHP(S)(NMe2)Cl differs markedly from its PO counterpart: the rate of substitution is increased much more by a 4-nitro substituent but is also more sensitive to the bulk of the amine, there is greater discrimination between competing nucleophiles, and with R2ND there is relatively little H–D exchange at the α carbon atom prior to substitution
在其中R反应2在CHCl NH(R = Me或Et)3在P小号基板博士2 CHP(S)(NME 2)氯从其p明显不同O对应:取代速率由4更增加-硝基取代基,但对大部分胺,竞争性亲核试剂之间的区别更大,并且使用R 2 ND取代之前,α碳原子上的H–D交换相对较少。然而,P S和P O化合物似乎都通过消除加成机理发生反应。建议在P O情况下快速形成共轭碱,而消除氯离子以生成亚甲基氧代膦(膦)中间体是限速的,而P S底物的共轭碱可迅速消除氯离子,从而提供相对稳定的稳定性。亚甲基硫代磷烷 (硫代膦)中间体。