Enantioselective Photoredox Catalysis Enabled by Proton-Coupled Electron Transfer: Development of an Asymmetric Aza-Pinacol Cyclization
作者:Lydia J. Rono、Hatice G. Yayla、David Y. Wang、Michael F. Armstrong、Robert R. Knowles
DOI:10.1021/ja4100595
日期:2013.11.27
protocol for the reductive coupling of ketones and hydrazones is reported. These reactions proceed through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer (PCET) event jointly mediated by a chiral phosphoric acid catalyst and the photoredox catalyst Ir(ppy)2(dtbpy)PF6. Remarkably, these neutral ketyl radicals appear to remain H-bonded to the chiral conjugate
报道了第一个用于酮和腙还原偶联的高度对映选择性催化方案。这些反应通过由手性磷酸催化剂和光氧化还原催化剂 Ir(ppy)2(dtbpy)PF6 共同介导的协同质子耦合电子转移 (PCET) 事件产生的中性羰基自由基中间体进行。值得注意的是,在随后的 CC 键形成步骤过程中,这些中性羰基自由基似乎保持与布朗斯台德酸的手性共轭碱 H 键合,从而提供具有优异水平的非对映选择性和对映选择性的顺式 1,2-氨基醇衍生物. 这项工作首次证明了不对称催化中协同 PCET 活化的可行性和潜在益处。
Samarium-based Grignard-type addition of organohalides to carbonyl compounds under catalysis of CuI
作者:Shuhuan Xiao、Chen Liu、Bin Song、Liang Wang、Yan Qi、Yongjun Liu
DOI:10.1039/d1cc00965f
日期:——
Grignard-type additions were readily achieved under the mediation of CuI (10 mol%) and samarium (2 equiv.) by employing various organohalides, e.g. benzyl, aryl, heterocyclic and aliphatic halides (Cl, Br or I), and diverse carbonylcompounds (e.g. carbonic esters, carboxylic esters, acid anhydrides, acyl chlorides, ketones, aldehydes, propylene epoxides and formamides) to afford alcohols, ketones
Iron-Catalyzed C–C Single-Bond Cleavage of Alcohols
作者:Wei Liu、Qiang Wu、Miao Wang、Yahao Huang、Peng Hu
DOI:10.1021/acs.orglett.1c03137
日期:2021.11.5
An iron-catalyzed deconstruction/hydrogenation reaction of alcohols through C–C bond cleavage is developed through photocatalysis, to produce ketones or aldehydes as the products. Tertiary, secondary, and primary alcohols bearing a wide range of substituents are suitable substrates. Complex natural alcohols can also perform the transformation selectively. A investigation of the mechanism reveals a
Soluble highly reactive form of calcium and reagents thereof
申请人:Board of Regents of the University of Nebraska
公开号:US05211889A1
公开(公告)日:1993-05-18
A soluble highly reactive form of calcium, prepared from Ca(II) salts and a reducing agent in ethereal, polyethereal, or hydrocarbon solvents, is presented. This form of calcium can be used in the preparation of organocalcium reagents. The organocalcium reagents resulting from the reaction of the soluble highly reactive calcium with organic compounds containing either halide, cyanide, a 1,3-diene, or a polyunsaturated functionality, are stable, useful reagents for organic synthesis. The organocalcium halide reagents undergo Grignard-type reactions. They also undergo reactions with Cu(I) salts to form organocalcium cuprate reagents. The organocalcium cuprate reagents undergo a variety of cross-coupling reactions. The soluble highly reactive calcium reacts with 1,3-dienes to yield the corresponding 2-butene-1,4-diylcalcium complexes. These bis-organocalcium reagents can undergo dialkylation reactions with .alpha.,.omega.-alkylene dihalides and dichlorosilanes to form the corresponding 3-, 5-, and 6-membered ring derivatives. The soluble highly reactive calcium also reacts with organic dihalides to form mono- or diorganocalcium compounds which can be converted into a wide variety of polymers.
We report the first terminal trifluoromethylation at aryl and alkyl ketones’ γ, δ, ε, or more remote sites via the selective C–C bond cleavage of cycloalkanols. The noncovalent interactions between alcohols and hypervalent iodines(III) reagents were disclosed to activate both alcohols and the Togni I reagent in the dual photoredox/copper catalysis for the transformation. This reaction was scalable
我们报告了通过环烷醇的选择性 C-C 键断裂在芳基和烷基酮的 γ、δ、ε 或更远的位点发生的第一个末端三氟甲基化。公开了醇和高价碘 (III) 试剂之间的非共价相互作用,以在双光氧化还原/铜催化转化中激活醇和 Togni I 试剂。该反应可扩展到克级合成,适用于结构复杂的类固醇三氟甲基化,并可扩展到五氟乙基化。