Selective Synthesis of <i>Z</i>-Silyl Enol Ethers via Ni-Catalyzed Remote Functionalization of Ketones
作者:Sinem Guven、Gourab Kundu、Andrea Weßels、Jas S. Ward、Kari Rissanen、Franziska Schoenebeck
DOI:10.1021/jacs.1c01797
日期:2021.6.9
the Z-selective synthesis of silyl enol ethers of (hetero)aromatic and aliphatic ketones via Ni-catalyzed chain walking from a distant olefin site. The positional selectivity is controlled by the directionality of the chain walk and is independent of thermodynamic preferences of the resulting silyl enol ether. Our mechanistic data indicate that a Ni(I) dimer is formed under these conditions, which
我们报告了一种远程官能化策略,该策略允许通过 Ni 催化的链从远处的烯烃位点步行来Z选择性合成(杂)芳族和脂肪族酮的甲硅烷基烯醇醚。位置选择性由链游走的方向性控制,并且与所得甲硅烷基烯醇醚的热力学偏好无关。我们的机理数据表明,在这些条件下形成Ni (I)二聚体,作为催化剂静止状态,并在与烷基溴反应后转化为 [Ni (II) -H] 作为活性链行走/功能化催化剂,最终生成稳定的 η 3 键合Ni (II) 烯醇作为关键的选择性控制中间体。
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.
α-Nitration of Ketones <i>via</i> Enol Silyl Ethers. Radical Cations as Reactive Intermediates in Thermal and Photochemical Processes
作者:Rajendra Rathore、Jay K. Kochi
DOI:10.1021/jo9515687
日期:1996.1.1
silyl ether (ESE) to TNM results in the radical ion triad [ESE(*)(+), NO(2)(*), C(NO(2))(3)(-)]. A subsequent fast homolytic coupling of the cation radical of the enol silyl ether with NO(2)(*)() leads to the alpha-nitro ketones. The use of time-resolved spectroscopy and the disparate behavior of the isomeric enol silyl ethers of alpha- and beta-tetralones as well as of 2-methylcyclohexanone strongly
Visible-light-promoted oxidative [4 + 2] cycloadditions of ε,3-unsaturated silyl enol ethers have been developed to efficiently and diastereoselectively construct polycyclic skeletons under mild conditions. The diastereoselectivities were dependent on the stereoconfiguration of silyl enol ether, substitutions on the link, as well as electric properties of substitutions on aryl rings. The intermediates