PDF(Pubmed)
Abstract：
Although ylides are commonly used reagents in organic synthesis, the parent methylphosphine MePH2 only exists in its phosphine form in the condensed phase. Its ylide tautomer H3 P+ -CH2 - is considerably higher in energy. Here, we report on the formation of bis(sulfonyl)methyl-substituted phosphines of the type (RO2 S)2 C(H)-PR2, which form stable PH ylides under ambient conditions, amongst the first examples of an acyclic phosphine which only exists in its PH ylide form. Depending on the exact substitution pattern the phosphines form an equilibrium between the PH ylide and the phosphine form or exist as one of both extremes. These phosphines were found to be ideal starting systems for the facile formation of α-carbanionic phosphines. The carbanion-functionalization leads to a switch from electron-poor to highly electron-rich phosphines with strong donor abilities and high basicities. Thus, the phosphines readily react with different electrophiles exclusively at the phosphorus atom and not at the carbanionic center. Furthermore, the anionic nature of the phosphines allows the formation of zwitterionic complexes as demonstrated by the isolation of a gold(I) complex with a cationic metal center. The cationic gold center allows for catalytic activity in the hydroamination of alkyne without requiring a further activation step.
摘要：
虽然叶立德是有机合成中常用的试剂，母体甲基膦MePH2仅以其膦形式存在于凝聚相中。其叶立德互变异构体H3P+-CH2-的能量相当高。这里,我们报告了（RO2S）2C（H）-PR2型双（磺酰基）甲基取代的膦的形成，在环境条件下形成稳定的PH叶立德，在仅以其PH叶立德形式存在的无环膦的第一个实例中。根据确切的取代模式，膦在PH叶立德和膦形式之间形成平衡，或者作为两种极端之一存在。发现这些膦是容易形成α-碳阴离子膦的理想起始体系。碳阴离子官能化导致从贫电子到具有强供体能力和高碱性的高度富电子的膦的转换。因此，膦易于仅在磷原子而不是在碳阴离子中心与不同的亲电体反应。此外，膦的阴离子性质允许形成两性离子络合物,如通过分离具有阳离子金属中心的金(I)络合物所证明的。阳离子金中心允许在炔烃的加氢胺化中的催化活性,而不需要进一步的活化步骤。
