Synthesis and asymmetric catalytic application of chiral imidazolium–phosphines derived from (1R,2R)-trans-diaminocyclohexane
作者:Richard Hodgson、Richard E. Douthwaite
DOI:10.1016/j.jorganchem.2005.07.110
日期:2005.12
gives the corresponding NHC–P ligands that can be used in metal-mediated asymmetric catalytic applications. Catalytic reactions show that NHC–P ligands give a significantly greater rate of reaction for a palladium catalysed allylic substitution reaction in comparison to analogous di-NHC or NHC–imine ligands and that NHC–P hybrids are also effective for iridium catalysed transfer hydrogenation.
(1 R,2 R)-反式-二氨基环己烷衍生的手性咪唑-胺前体与P 1 Cl(其中P 1 = PPh 2,P(1,3,5-Me 3 C 6 H 3)2)之间的反应P(2,2'- O,O '-(1,1'-联苯),P((R)-(2,2'- O,O '-(1,1'-联萘基))))和P。((S)-(2,2'- O,O '-(1,1'-联萘基))))然后是RX(其中R = n Pr,i Pr,CHPh 2,X = Br;R = i Pr,X = I)分别给出了手性咪唑鎓膦化合物的选择。咪唑鎓盐的去质子化反应可得到相应的NHC-P配体,该配体可用于金属介导的不对称催化应用中。催化反应表明,与类似的di-NHC或NHC-亚胺配体相比,NHC-P配体对钯催化的烯丙基取代反应的反应速率明显更高,并且NHC-P杂化物对铱催化的转移氢化也有效。