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。
Oxidative α-C–C Bond Cleavage of 2° and 3° Alcohols to Aromatic Acids with O<sub>2</sub> at Room Temperature via Iron Photocatalysis
cleavage of unfunctionalized secondary (2°) and tertiary alcohols (3°) is essential for valorization of macromolecules and biopolymers. We developed a blue-light-driven iron catalysis for aerobic oxidation of 2° and 3° alcohols to acids via α-C–C bond cleavages at room temperature. The first example of oxygenation of the simple tertiary alcohols was reported. The iron catalyst and blue light play critical
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
Iodine-Promoted Metal-Free Aromatization: Synthesis of Biaryls, Oligo<i>p</i>-Phenylenes and A-Ring Modified Steroids
作者:Victoriano Domingo、Consuelo Prieto、Alexis Castillo、Lucia Silva、José F. Quílez del Moral、Alejandro F. Barrero
DOI:10.1002/adsc.201500303
日期:2015.10.12
efficient procedures based on the use of iodine for the synthesis of biaryls from arylcyclohexenols or arylcyclohexanols using sub-stoichiometric/catalytic iodine and dimethyl sulfoxide (DMSO) as oxidant. Heteroarylcyclohexanols also produced the corresponding biaryl products. It was proven that biphenyl can also be efficiently obtained when the quantity of iodine was reduced to 0.05 equiv. The method
Enantioselective Nickel-Catalyzed Alkyne–Azide Cycloaddition by Dynamic Kinetic Resolution
作者:En-Chih Liu、Joseph J. Topczewski
DOI:10.1021/jacs.1c01354
日期:2021.4.14
α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne–azide cycloaddition (NiAAC). This dynamic kineticresolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived