Distinctive Meta-Directing Group Effect for Iridium-Catalyzed 1,1-Diarylalkene Enantioselective Hydrogenation
摘要:
An iridium-catalyzed asymmetric hydrogenation of 1,1-diarylkenes is described. Employing a novel, modular phosphoramidite ligand, PhosPrOx, in this transformation affords biologically relevant 1,1-diarylmethine products in good enantiomeric ratios (96.5:3.5 to 71:29). We propose that a meta-directing group, 3,5-dimethoxyphenyl, is responsible for the observed enantioselection, the highest reported, to date, for iridium-catalyzed hydrogenation of 1,1-diarylalkenes lacking ortho-directing groups.
additions to organic carbonyls. Aryl additions of AlArEt2(THF) to aldehydescatalyzed by the titanium(IV) complex of (R)-H8−BINOL were efficient with a short reaction time of 1 h, affording aryl addition products as exclusive or main products in high yields and excellent enantioselectivities of up to 98% ee. Although ethyl additions to aldehydes occurred in minor extent, this study demonstrates that increasing
一系列AlArEt 2(THF)(Ar = Ph(1a),4-MeC 6 H 4(1b),4-MeOC 6 H 4(1c),4-Me 3 SiC 6 H 4(1d),2-由AlEt 2 Br(THF)与ArMgBr的反应合成萘基(1e)。在CDCl 3溶液中,1 H NMR光谱表明,AlArEt 2(THF)化合物以AlAr x Et 3- x(THF)(x= 0、1、2或3)。发现AlArEt 2(THF)化合物是不对称芳基加成到有机羰基化合物中的优良化合物,并且是原子经济的试剂。由(R)-H 8 -BINOL的钛(IV)络合物催化的AlArEt 2(THF)芳基加成醛的反应效率高,反应时间短至1 h,从而以高收率提供芳基加成产物作为独家产物或主要产物以及高达98%ee的优异对映选择性。尽管乙醛中乙醛的添加量很小,但这项研究表明,增加AlArEt 2的含量(THF)从1.2到1.4或到1
A New Aspect of Magnesium Bromide‐Promoted Enantioselective Aryl Additions of Triaryl(tetrahydrofuran)aluminum to Ketones Catalyzed by a Titanium(IV) Catalyst of<i>trans</i>‐1,2‐Bis(hydroxycamphorsulfonylamino)cyclohexane
作者:Chien‐An Chen、Kuo‐Hui Wu、Han‐Mou Gau
DOI:10.1002/adsc.200800169
日期:2008.7.7
A novel aspect of MgBr2-promoted asymmetric triarylaluminum-tetrahydrofuran [AlAr3(THF)] additions to ketonescatalyzed by a titanium catalyst of 20 mol% trans-1,2-bis(hydroxycamphorsulfonylamino)cyclohexane (2) is reported. The catalytic system works excellently for aromatic ketones with either an electron-withdrawing or an electron-donating substituent on the aromatic ring at the 2′-, 3′-, or 4′-positions
报道了由MgBr 2促进的不对称三芳基铝-四氢呋喃[AlAr 3(THF)]加成在由20摩尔%的反式-1,2-双(羟基樟脑磺酰基氨基)环己烷(2)钛催化剂催化的酮中的新变化。催化体系对芳族酮具有出色的作用,该芳族酮在2'-,3'-或4'-位的芳香环上具有吸电子或供电子取代基,可提供≥90%的优异对映选择性的叔醇ee,除了在2'-甲氧基苯乙酮中添加苯基和在乙炔酮中添加4-三甲基甲硅烷基苯基(4-TMSC 6 H 4)的情况。
Electron transfer in reactions of ketones with organolithium reagents. A carbon-14 kinetic isotope effect probe
of ketones and reagents. The reaction of benzophenone with MeLi proceeds via rate-determining electrontransfer; the change in nucleophile from MeLi to Me/sub 2/CuLi shifts the rate-determining step from electrontransfer to recombination; the change in ketone from benzophenone to 2,4,6-trimethylbenzophenone also shifts the rate-determining step from electrontransfer to recombination because the latter
Chiral diamine compounds for the preparation of chiral alcohols and chiral amines
申请人:University College Dublin
公开号:US10196338B2
公开(公告)日:2019-02-05
Processes for stereoselective preparation of a chiral alcohol or a chiral amine are described. The processes include reacting a first prochiral reactant selected from the group consisting of a ketone, an aldehyde, and an imine, with a second reactant that includes a Grignard reagent, in the presence of a chiral trans-diamine of formula (1) as defined herein:
In this report, we describe a practical, ligand-free, nickel-catalyzed carbonyl addition reaction using organoboron reagents that enables an efficient synthesis of both tertiary and secondary alcohols across a broad scope.