A series of hybrid phosphine–phosphoramiditeligands has been designed and synthesized in moderate yields from chiral BINOL (1,1′‐bi‐2‐naphthol) or NOBIN (2‐amino‐2′‐hydroxy‐1,1′‐binaphthyl). They have achieved highly regio‐ and enantioselectivities in Rh‐catalyzed asymmetrichydroformylations of styrene derivatives (branched/linear ratio up to 56.6, ee up to 99 %), vinyl acetate derivatives (up to
Synthesis and Application of a New Bisphosphite Ligand Collection for Asymmetric Hydroformylation of Allyl Cyanide
作者:Christopher J. Cobley、Kelli Gardner、Jerzy Klosin、Céline Praquin、Catherine Hill、Gregory T. Whiteker、Antonio Zanotti-Gerosa、Jeffrey L. Petersen、Khalil A. Abboud
DOI:10.1021/jo040128p
日期:2004.6.1
auxiliary and screened in the asymmetrichydroformylation of allyl cyanide. These hydroformylation results were compared with those of two existing chiral ligands, Chiraphite and BINAPHOS, whose utility in asymmetrichydroformylation has been previously demonstrated. Bisphosphite 11 with a 2,2‘-biphenol bridge was found to be the best overall ligand for asymmetrichydroformylation of allyl cyanide with up
用(S)-5,5',6,6'-四甲基-3,3'-二叔叔丁基-1,1'-联苯-2,2'-制备了一系列单亚磷酸酯和亚磷酸酯亚磷酸酯二氧基[(S)-BIPHEN]作为手性助剂,并在烯丙基氰化物的不对称加氢甲酰化反应中进行了筛选。将这些加氢甲酰化的结果与两个现有的手性配体Chiraphite和BINAPHOS的结果进行了比较,后者已在不对称加氢甲酰化中得到了证明。发现具有2,2'-双酚桥的双亚磷酸酯11是烯丙基氰化物不对称加氢甲酰化的最佳整体配体,ee高达80%ee,区域选择性(分支线性比,b / l)为20,且具有翻转频率的625 [h - 1]在35°C下。当反应在丙酮或纯净条件下进行时,BINAPHOS的对映选择性高达77%ee,但区域选择性差(b / l 2.8),活性比11低7倍。随后将使用(R,R)-11的烯丙基氰化物加氢甲酰化产物转化为(R)-2-甲基-4-氨基丁醇,一种有用的手性结
An Asymmetric Hydroformylation Catalyst that Delivers Branched Aldehydes from Alkyl Alkenes
作者:Gary M. Noonan、José A. Fuentes、Christopher J. Cobley、Matthew L. Clarke
DOI:10.1002/anie.201108203
日期:2012.3.5
Surprising selectivity: The first enantioselective hydroformylations of simple alkenes of type RCH2CHCH2 to preferentially deliver the branchedaldehyde product have been discovered using a new chiral ligand, named bobphos (see scheme). Established ligands are unselective in this reaction or show a slight preference towards the linear aldehyde.
Chiral Phosphine−Phosphite Ligands with a Substituted Ethane Backbone. Influence of Conformational Effects in Rhodium-Catalyzed Asymmetric Olefin Hydrogenation and Hydroformylation Reactions
catalysts for the hydrogenation of methyl (Z)-α-acetamidocinnamate (MAC) and dimethyl itaconate. The catalyst comparison indicates that, for the two substrates, product configuration is determined by the configuration of the phosphite. Regarding matching and mismatchingeffects in these hydrogenations, small effects were observed in the reduction of MAC, while for the itaconate the bigger difference between
under mild reaction conditions. The modular nature of the ligands allows fine-tuning of the selectivities through judicious modifications of the substituents on the ligand backbone. X-ray structural analysis of the catalyst precursor suggested that the steric hindrance caused by the protruding remote substituents of the ligands into the vicinity of the metal center might be an important factor for