New Homochiral Ligands Bearing Nonstereogenic Chirotopic Centers. Lithiated N,N‘-Dialkylureas as Chiral Bases and Sterically Crowded Phosphines for Asymmetric Catalysis
摘要:
The synthesis of new homochiral pseudo-C-2-symmetrical ligands of type 1 bearing a nonstereogenic chirotopic center is reported. Two such structural units are combined in the ureas 2 and 10, which proved to be useful for enantioselective deprotonation and alkylation of ketones (up to 88% ee). The monophosphine 3 induced a high enantiomeric excess in the Pd-catalyzed allylation of dimethyl malonate (up to 73% ee). Furthermore, we have shown that the achiral sterically crowded alkyl diphosphine 23 efficiently stabilized Pd(0) at high temperatures.
traditional C −C cross‐coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the crosscoupling of allylstannanes and activated alkylbromides to form C −C bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solidsupport, which allowed
Promotion of Appel-type reactions by N-heterocyclic carbenes
作者:Mohanad A. Hussein、Thanh Vinh Nguyen
DOI:10.1039/c9cc02132a
日期:——
N-Heterocycliccarbenes (NHCs) have been extensively used as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a
POLYCYCLIC COMPOUNDS AS LYSOPHOSPHATIDIC ACID RECEPTOR ANTAGONISTS
申请人:CLARK Ryan
公开号:US20110082164A1
公开(公告)日:2011-04-07
Described herein are compounds that are antagonists of lysophosphatidic receptor(s). Also described are pharmaceutical compositions and medicaments that include the compounds described herein, as well as methods of using such antagonists, alone and in combination with other compounds, for treating LPA-dependent or LPA-mediated conditions or diseases.
One-Pot Deoxygenation and Substitution of Alcohols Mediated by Sulfuryl Fluoride
作者:Maxim Epifanov、Jia Yi Mo、Rudy Dubois、Hao Yu、Glenn M. Sammis
DOI:10.1021/acs.joc.0c02557
日期:2021.3.5
intermediates. This strategy allows the expansion of SO2F2-mediated one-pot processes to include radical reactions, where the alkyl halides can also be exploited in the one-pot deoxygenation of primary alcohols under mild conditions (52–95% yield). This strategy can also enhance the scope of substitutions to nucleophiles that are previously incompatible with one-pot SO2F2-mediated alcohol activation and enables
硫酰氟是用于一键活化和衍生化脂肪醇的有价值的试剂,但是高反应性的烷基氟硫酸烷基酯中间体限制了可以进行的反应类型以及反应范围。在本文中,我们报道了SO 2 F 2介导的醇取代和脱氧方法,该方法依赖于氟代硫酸盐向烷基卤化物中间体的转化。该策略允许扩展SO 2 F 2介导的一锅法包括自由基反应,其中烷基卤也可在温和条件下(52-95%的收率)用于伯醇的一锅法脱氧。这种策略还可以扩大以前与一锅SO 2 F 2介导的醇活化不相容的亲核试剂的取代范围,并能够以54-95%的产率取代伯醇和仲醇。手性仲醇具有高度立体特异性(90-98%ee)的双亲核取代,且整体保留构型。
Transition-Metal-Free Stereospecific Cross-Coupling with Alkenylboronic Acids as Nucleophiles
We herein report a transition-metal-free cross-coupling between secondaryalkylhalides/mesylates and aryl/alkenylboronic acid, providing expedited access to a series of nonchiral/chiral coupling products in moderate to good yields. Stereospecific SN2-type coupling is developed for the first time with alkenylboronic acids as pure nucleophiles, offering an attractive alternative to the stereospecific