描述了基于在硫原子上被芳基或烷基自由基的分子内均质取代(S H i)合成环状亚磺酸酯和亚磺酰胺的通用且有效的方法。烷基和苯并稠合的化合物都可以直接从容易制备的无环前体中获得。对映体富集的硫基杂环是通过S H i过程形成的,硫原子上的构型反转。前手性自由基的环化进行的立体化学结果各不相同,具体取决于传入自由基的大小。2-吡啶基和2-喹啉基会生成联芳基化合物,这是由于攻击芳基亚磺酸盐的邻位而不是亲硫取代引起的。
Iron(II) and Copper(I) Control the Total Regioselectivity in the Hydrobromination of Alkenes
作者:Daniel A. Cruz、Victoria Sinka、Pedro de Armas、Hugo Sebastian Steingruber、Israel Fernández、Víctor S. Martín、Pedro O. Miranda、Juan I. Padrón
DOI:10.1021/acs.orglett.1c02186
日期:2021.8.6
A new method that allows the complete control of the regioselectivity of the hydrobrominationreaction of alkenes is described. Herein, we report a radical procedure with TMSBr and oxygen as common reagents, where the formation of the anti-Markovnikov product occurs in the presence of parts per million amounts of the Cu(I) species and the formation of the Markovnikov product occurs in the presence
Asymmetric Alkyl−Alkyl Cross-Couplings of Unactivated Secondary Alkyl Electrophiles: Stereoconvergent Suzuki Reactions of Racemic Acylated Halohydrins
作者:Nathan A. Owston、Gregory C. Fu
DOI:10.1021/ja105924f
日期:2010.9.1
A method for asymmetric alkyl-alkylSuzuki reactions of unactivatedsecondaryalkyl electrophiles, specifically, cross-couplings of racemic acylated halohydrins with alkylborane reagents, has been developed. A range of protected bromohydrins, as well as a protected chlorohydrin and a homologated bromohydrin, are coupled in good ee by a catalyst derived from commercially available components.
已开发出一种用于未活化仲烷基亲电试剂的不对称烷基-烷基 Suzuki 反应的方法,特别是外消旋酰化卤代醇与烷基硼烷试剂的交叉偶联。一系列受保护的溴醇,以及受保护的氯醇和同系溴醇,通过衍生自市售组分的催化剂以良好的 ee 偶联。
Ni-Catalyzed Formal Cross-Electrophile Coupling of Alcohols with Aryl Halides
作者:Quan Lin、Guobin Ma、Hegui Gong
DOI:10.1021/acscatal.1c04239
日期:2021.11.19
and TBAB as the mild bromination reagents enables rapid transformation of a wide range of alcohols to their bromide counterparts within one to 5 min in CH3CN and DMF, which is compatible with the Ni-catalyzed cross-electrophile coupling conditions in the presence of a chemical reductant. The present method is suitable for arylation of a myriad of structurally complex alcohols with no need for prepreparation
未活化醇的直接偶联仍然是当前合成化学中的一个挑战。我们在此展示了一种建立在醇与芳基卤化物的原位卤化/还原偶联以形成 Csp 2 -Csp 3键的策略。2-氯-3-乙基苯并[ d ]恶唑-3-鎓盐 (CEBO) 和 TBAB 作为温和溴化试剂的组合能够在 CH 3 中在一到 5 分钟内将范围广泛的醇快速转化为其溴化物对应物CN 和 DMF,在化学还原剂存在下与 Ni 催化的交叉亲电偶联条件相容。本方法适用于无数结构复杂的醇的芳基化,而无需制备卤代烷。更重要的是,温和且动力学快速的溴化过程在对称二醇的溴化/芳基化和多元醇中较少的空间位阻羟基中显示出良好的选择性,从而为二醇和多元醇的选择性官能化提供了希望,而无需费力的保护/脱保护操作。这项工作的实用性在许多碳水化合物、药物化合物和天然醇的芳基化中也很明显。
Stereoselective Radical Aryl Migration Reactions from Sulfur to Carbon
Stereoselective aryl migration reactionsfromsulfur in sulfonates and sulfonamides to C-centered radicals are reported. The 1,5-aryl migration fromsulfur to differently substituted C-centered radicals could be performed with high yields and selectivities. Functionalized aryl groups could also be transferred by this new method. A model to explain the stereochemical outcome of the reaction is presented and some
Platinum‐Catalyzed Desaturation of Lactams, Ketones, and Lactones
作者:Ming Chen、Alexander J. Rago、Guangbin Dong
DOI:10.1002/anie.201811197
日期:2018.12.3
desaturation of N‐protected lactams, ketones, and lactones to their conjugated α,β‐unsaturated counterparts is reported. The reaction operates under mildly acidic conditions at room temperature or 50 °C. It is scalable and tolerates a wide range of functional groups. The complementary reactivity to the palladium‐catalyzed desaturation is demonstrated in the efficient conversion of iodide, bromide, and sulfur‐containing