The ligand-exchange process of P-Hapical phosphoranes and the thermal formation and pseudorotation of anti-apicophilic spirophosphoranes
The ligand-exchange process of P-Hapical phosphoranes and the thermal formation and pseudorotation of anti-apicophilic spirophosphoranes
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DOI：
10.1002/ejoc.200500510
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发表时间：
2006-01-01
影响因子：
2.8
通讯作者：
Akiba, K
中科院分区：
文献类型：
--
作者：
Kojima, S;Kajiyama, K;Akiba, K
带有开环马丁配体的单环P-H-顶端正膦10在用大于2当量的P-H-赤道螺正膦7处理后形成。烷基锂化合物。发现这些正膦10的配体交换过程涉及双齿马丁配体与单齿马丁配体的相互转化，可能通过六配位磷原子进行。加热10在nondonating溶剂提供烷基螺膦5，而加热10在供体溶剂中导致反apicophilic膦6，一类新的膦，其中较少apicophilic碳取代基占据顶端位置和更apicophilic氧原子占据赤道位置的形成。发现这些正膦6在加热时完全转化成其能量上更稳定的C-赤道、O-顶端立体异构体5。10的环化过程的动力学检查的基础上，6的形成可以合理化的增强亲核性的羟基基团在供体溶剂。通过对6 b到5 b的假旋转动力学研究，估计异构体5 b比6 b（R = nBu）稳定12 kcal mol（-1）。这与类似的5a和6a（R = Me）的理论计算结果非常一致，后者估计能量差为14.1 kcal mol（-1）。((c)Wiley-VCH Verlag GmbH & Co. KGaA，69451魏因海姆，德国，2006）。
Monocyclic P-H-apical phosphoranes 10 bearing a ring-opened Martin ligand are formed upon treatment of the P-H-equatorial spirophosphorane 7 with more than 2 equiv. of alkyllithium compounds. A ligand-exchange process of these phosphoranes 10 involving the interconversion of the bidentate Martin ligand with the monodentate Martin ligand was found to proceed, probably through a hexacoordinate phosphorus atom. Heating of 10 in nondonating solvents furnished alkylspirophosphoranes 5, whereas heating of 10 in donor solvents led to the formation of anti-apicophilic phosphoranes 6, a new class of phosphoranes in which the less apicophilic carbon substituent occupies an apical position and the more apicophilic oxygen atom occupies an equatorial position. These phosphoranes 6 were found to completely convert into their energetically more stable C-equatorial,O-apical stereoisomers 5 upon heating. On the basis of kinetic examinations of the cyclization process of 10, the formation of 6 can be rationalized by the enhanced nucleophilicity of the hydroxy group in the donor solvents. The isomer 5b was estimated to be more stable than 6b (R = nBu) by 12 kcal mol(-1) from kinetic studies on the pseudorotation of 6b to 5b. This is in good agreement with theoretical calculations with analogous 5a and 6a (R = Me), which estimate the difference in energy to be 14.1 kcal mol(-1). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).