Enantioselective Redox-Neutral Rh-Catalyzed Coupling of Terminal Alkynes with Carboxylic Acids Toward Branched Allylic Esters
作者:Philipp Koschker、Matthias Kähny、Bernhard Breit
DOI:10.1021/jacs.5b01131
日期:2015.3.4
We report on the first enantioselective variant of the atom-economic and redox-neutral coupling of carboxylic acids with terminal alkynes under rhodium catalysis utilizing the chiral, bidentate (R,R)-Cp-DIOP ligand. This represents the first example of this convenient asymmetric access to valuable branched allylic esters. The utility of this methodology is demonstrated by both a reaction performed on large scale and a short three-step synthesis of two naturally occurring gamma-butyrolactones. A stereochemical model explaining the observed absolute configuration of the products based on DFT calculations is given.
US4204997A
申请人:——
公开号:US4204997A
公开(公告)日:1980-05-27
Rhodium-Catalyzed Enantioselective Radical Addition of CX<sub>4</sub>
Reagents to Olefins
作者:Bo Chen、Cheng Fang、Peng Liu、Joseph M. Ready
DOI:10.1002/anie.201704074
日期:2017.7.17
We describe the synthetically useful enantioselective addition of Br−CX3 (X=Cl or Br) to terminal olefins to introduce a trihalomethyl group and generate optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom‐transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer‐sphere bromine abstraction from a [(bisphosphine)RhIIBrCl]
我们描述了Br-CX 3(X = Cl或Br)的合成有用的对映选择性加成到末端烯烃中以引入三卤甲基并生成光学活性的仲溴化物。计算和实验证据支持不对称原子转移自由基加成(ATRA)机理,其中立体确定步骤涉及通过苄基自由基中间体从[(bisphosphine)Rh II BrCl]络合物中提取外层溴。这种机理在不对称催化中显得空前。