Phenylphosphatrioxa-adamantanes: bulky, robust, electron-poor ligands that give very efficient rhodium(I) hydroformylation catalysts
Phenylphosphatrioxa-adamantanes: bulky, robust, electron-poor ligands that give very efficient rhodium(I) hydroformylation catalysts
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DOI：
10.1039/b418259f
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发表时间：
2005-01-01
影响因子：
4
通讯作者：
Zambrano-Williams, DE
中科院分区：
文献类型：
--
作者：
Baber, RA;Clarke, ML;Zambrano-Williams, DE
通过将PhPH2与相应的β -二酮酸催化加成，制备了笼形膦1,3,5,7-四甲基-6-苯基-2,4,8-三氧基-6-磷金刚烷（1a）和1,3,5,7-四乙基-6-苯基-2,4,8-三氧基-6-磷金刚烷（1b）；使用的酸（HCl， H3PO4或H2SO4）及其浓度影响这些缩合反应的速率和选择性。膦1a和1b与[PdCl2(NCPh)(2)]反应形成反式-[PdCl2(1a)(2)] （2a）和反式-[PdCl2(1b)(2)] （2b）作为rac和中介面非对映异构体的混合物。铂（II）的化学性质更为复杂，当1a或1b加入[PtCl2(cod)]时，在CH2Cl2溶液中形成反式-[PtCl2L2]和[Pt2Cl4L2] （L = 1a或1b）的平衡混合物。在MCl3的作用下，形成了反式-[MCl(CO)(1a)(2)] M = Ir （6a）或Rh （7a）的中位/rac混合物。从CoCl2.6H(2)O与1a形成的产物中分离出过量的nH(2)O和阴离子钴配合物[nhe3][CoCl3(1a)](9)。6a和7a的红外光谱nu（CO）值表明，1a与Rh和IR的结合类似于膦酸盐。报道了meso-2a、meso-2b、rac-6a和9的晶体结构，在每种情况下，观察到小的内部C-P-C角约为94度，这可以部分解释配体1a和1b的键合特性。1a和1b的锥角相似且较大（约200）。配体1a和1b的铑配合物是氢甲酰化催化剂，与亚磷酸盐衍生的催化剂具有相似的高活性。由1a和1b衍生的催化剂在己烯的氢甲酰化反应中具有异常低的线性选择性。这一特征在不饱和酯的季铵盐选择性氢甲酰化反应中得到了进一步的利用；从1a衍生的催化剂比以前报道的任何催化剂都具有更好的产率和区域选择性。
The cage phosphines 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane (1a) and 1,3,5,7-tetraethyl-6-phenyl-2,4,8,trioxa-6-phosphaadamantane (1b) have been made by the acid catalysed addition of PhPH2 to the appropriate beta-diketones; the acid used (HCl, H3PO4 or H2SO4) and its concentration affect the rate and selectivity of these condensation reactions. Phosphines 1a and 1b react with [PdCl2(NCPh)(2)] to form complexes trans-[PdCl2(1a)(2)] (2a) and trans-[PdCl2(1b)(2)] (2b) as mixtures of rac and meso diastereoisomers. The platinum(II) chemistry is more complicated and when 1a or 1b is added to [PtCl2(cod)], equilibrium mixtures of trans-[PtCl2L2] and [Pt2Cl4L2] (L = 1a or 1b) are formed in CH2Cl2 solution. Meso/rac mixtures of trans-[MCl(CO)(1a)(2)] M = Ir (6a) or Rh (7a) are formed upon treatment of MCl3.nH(2)O with an excess of 1a and the anionic cobalt complex [NHEt3][CoCl3(1a)] (9) was isolated from the product formed by CoCl2.6H(2)O and 1a. The nu(CO) values from the IR spectra of 6a and 7a suggest that 1a resembles a phosphonite in its bonding to Rh and Ir. Crystal structures of meso-2a, meso-2b, rac-6a and 9 are reported and in each case a small intracage C-P-C angle of ca. 94degrees is observed and this may partly explain the bonding characteristics of ligands 1a and 1b. The cone angles for 1a and 1b are similar and large (ca. 200). Rhodium complexes of ligands 1a and 1b are hydroformylation catalysts with similarly high activity to catalysts derived from phosphites. The catalysts derived from 1a and 1b gave unusually low linear selectivity in the hydroformylation of hexenes. This feature has been further exploited in quaternary-selective hydroformylations of unsaturated esters; catalysts derived from 1a give better yields and regioselectivities than any previously reported catalyst.