completed by reaction with a protic nucleophile for the synthesis of indenol derivatives with a tertiary center is described. Mechanistic studies and DFT calculations indicate that the transformation is initiated by a gold-promoted 5-endo-dig carbocyclization to form the key intermediate vinyl gold carbene, which is intercepted by an unprecedented vinylogous addition and followed by external protic nucleophile-assisted
By using a charcoal supported nano Cu0 catalyst (Cu/C), a highly efficient oxidation of α-diazo esters to α-ketoesters with molecular oxygen as the sole oxidant has been developed. In the presence of the Cu/C catalyst, 2-aryl-α-diazo esters with both electron-donating and electron-withdrawing groups can be oxidized to the corresponding α-ketoesters efficiently. Furthermore, this Cu/C catalyst can catalyse
The thionophosphate–thiolophosphate † photoisomerization proceeds predominantly through a non-chain radical pathway. Synthetically viable benzylation of tetrahydrofuran, propan-2-ol and olefins ‡
作者:Veejendra K. Yadav、Rengarajan Balamurugan、Masood Parvez、Raghav Yamdagni
DOI:10.1039/b003501g
日期:——
The photoirradiation of thionophosphates, ROP(S)(OEt)2, derived from benzyl and vinylogously benzyl alcohols in CH3CN, with a Hanovia medium-pressure mercury lamp in a quartz vessel leads to the formation of the corresponding thiolophosphates, RSP(O)(OEt)2, through a non-chain radical pathway. This behavior of thionophosphates is unlike that of the related phosphates, which react through ionic dissociationârecombination processes. When the irradiation is conducted in solvents such as PriOH, THF and toluene, benzylation of these solvents takes place in synthetically respectable yields. Irradiation of thionophosphates in CH3CN leads to a convenient allylic benzylation of olefins.
Tridentate Nickel(II)-Catalyzed Chemodivergent C–H Functionalization and Cyclopropanation: Regioselective and Diastereoselective Access to Substituted Aromatic Heterocycles
作者:Ekta Nag、Sai Manoj N. V. T. Gorantla、Selvakumar Arumugam、Aditya Kulkarni、Kartik Chandra Mondal、Sudipta Roy
DOI:10.1021/acs.orglett.0c02138
日期:2020.8.21
Schiff-base nickel(II)-phosphene-catalyzed chemodivergent C–H functionalization and cyclopropanation of aromatic heterocycles is reported in moderate to excellent yields and very good regioselectivity and diastereoselectivity. The weak, noncovalent interaction between the phosphene ligand and Ni center facilitates the ligand dissociation, generating the electronically and coordinativelyunsaturated active
Copper-Catalyzed Synthesis of 2,4-Disubstituted Allenoates from α-Diazoesters
作者:Matthew Hassink、Xiaozhong Liu、Joseph M. Fox
DOI:10.1021/ol2006242
日期:2011.5.6
α-substituted-α-diazoesters with terminal alkynes to give substituted allenoates is described. Key to the development of a selective method was the recognition that an adventitous base catalyzes the isomerization to form the allenoate product. A plausible mechanism is proposed, based in part on evidence against a mechanism that involves a Cu(I)-acetylide as a low-valent intermediate.
描述了一种用于将 α-取代-α-重氮酯与末端炔烃偶联以产生取代的烯丙酸酯的 Cu 催化方法。开发选择性方法的关键是认识到外来碱催化异构化形成烯丙酸酯产物。提出了一种合理的机制,部分基于反对将 Cu(I)-乙炔化物作为低价中间体的机制的证据。