Stable P-heterocyclic carbenes: scope and limitations.
Stable P-heterocyclic carbenes: scope and limitations.
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DOI：
10.1002/asia.200600300
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发表时间：
2007-01
期刊：
影响因子：
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通讯作者：
Jason D. Masuda;David Martin;Céline Lyon-Saunier;A. Baceiredo;H. Gornitzka;B. Donnadieu;G. Bertrand
中科院分区：
文献类型：
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作者：
Jason D. Masuda;David Martin;Céline Lyon-Saunier;A. Baceiredo;H. Gornitzka;B. Donnadieu;G. Bertrand
通过1，3-二磷烯丙基或1，3-膦膦阳离子与不同的腈进行形式[3+2]环加成反应，合成了P-杂环卡宾的共轭酸(PHCH+S)。报道了磷取代基对环化反应的影响，以及在随后的去质子化反应中对反阴离子和碱的影响。描述了两种在固态中无限稳定的光子晶体。在溶液中，一个由乙腈制成的化合物进行了简单的[3+2]环还原反应，而另一个以二甲基氰胺为基础的化合物是稳定的，这可能是因为它的两性离子结构涉及一个三配位的五价磷原子。PHCS的反应性是由磷中心的高亲电性强烈驱动的，其与水和苯甲醛的反应证明了这一点。虽然本文报道的两种PHC都是最弱碱性NHC的直接类似物，但它们的碱性与更强碱性NHC的碱度相当(通过比较它们对应的顺式[RhCl-(CO)2(L)]络合物的羰基伸缩频率来确定)。
The conjugate acids (PHCH+s) of P-heterocyclic carbenes (PHCs) are prepared by formal [3+2] cycloaddition of a 1,3-diphosphaallyl or 1,3-phosphinophosphenium cation with various nitriles. The effect of the phosphorus substituent on the fate of the cyclization and on that of the counteranion and base in the subsequent deprotonation reaction are reported. Two PHCs that are indefinitely stable in the solid state are described. In solution, one of them, made from acetonitrile, undergoes a facile [3+2] cycloreversion, whereas the other, based on dimethyl cyanamide, is stable, presumably owing to its zwitterionic structure, which involves a tricoordinate pentavalent phosphorus atom. The reactivity of PHCs is strongly driven by the high electrophilicity of the phosphorus centers, as demonstrated by their reactivity with water and benzaldehyde. Although both PHCs reported in this paper are direct analogues of the least-basic NHCs, their basicity is comparable to those of the more strongly basic NHCs (as determined by comparison of the carbonyl stretching frequencies of their corresponding cis-[RhCl-(CO)2(L)] complexes).