Chiral Pincer Carbodicarbene Ligands for Enantioselective Rhodium-Catalyzed Hydroarylation of Terminal and Internal 1,3-Dienes with Indoles
作者:Justin S. Marcum、Courtney C. Roberts、Rajith S. Manan、Tia N. Cervarich、Simon J. Meek
DOI:10.1021/jacs.7b08575
日期:2017.11.8
Catalytic enantioselective addition of N-heteroarenes to terminal and internal 1,3-dienes is reported. Reactions are promoted by 5 mol % of Rh catalyst supported by a new chiral pincer carbodicarbene ligand that delivers allylic substituted arenes in up to 95% yield and up to 98:2 er. Mechanistic and X-ray evidence is presented that supports that the reaction proceeds via a Rh(III)-η3-allyl.
powerful methods for allylic oxidation of alkenes. However, the inherent radical mechanism and use of peroxides as both oxidants and oxygen nucleophiles render dearth of universal catalytic systems for highly enantioselective variants and limited scope. Herein, an alternative to the asymmetric Kharasch–Sosnovsky reaction that utilized a chiral coppercatalyst and purple-LED irradiation to enable the
Kharasch-Sosnovsky 反应是烯烃烯丙基氧化最有效的方法之一。然而,固有的自由基机制和过氧化物作为氧化剂和氧亲核试剂的使用导致缺乏用于高度对映选择性变体和有限范围的通用催化系统。在此,报道了不对称 Kharasch-Sosnovsky 反应的替代方案,该反应利用手性铜催化剂和紫色 LED 照射实现 1,3-二烯、肟酯和羧酸的三组分偶联。该协议具有温和的条件、显着的范围和官能团耐受性,> 80 个例子和在药物和天然产物的后期修饰中的效用证明了这一点。详细的机理研究为基于自由基的反应途径提供了证据。
Highly Regio- and Enantioselective Copper-Catalyzed Reductive Hydroxymethylation of Styrenes and 1,3-Dienes with CO<sub>2</sub>
yields and excellent regio-, enantio-, and Z/E-selectivities. The utility of this transformation was demonstrated by a broad range of styrenes and 1,3-dienes, facile product modification, and synthesis of bioactive compounds (R)-(-)-curcumene and (S)-(+)-ibuprofen. Mechanistic studies demonstrated the carboxylation of phenylethylcopper complexes with CO2 as one key step.
在此,我们报告了具有 1 个大气压的 CO2 的苯乙烯和 1,3-二烯的高度区域选择性和对映选择性铜催化还原羟甲基化。各种重要的手性高苄醇很容易从苯乙烯制备。此外,各种 1,3-二烯也以高产率和优异的区域选择性、对映选择性和 Z/E 选择性转化为手性高烯丙醇。广泛的苯乙烯和 1,3-二烯、简便的产品改性以及生物活性化合物 (R)-(-)-姜黄烯和 (S)-(+)-布洛芬的合成证明了这种转化的效用。机理研究表明,苯乙基铜配合物与 CO2 的羧化是一个关键步骤。
Palladium-Catalyzed Cascade Double C-N Bond Activation: A New Strategy for Aminomethylation of 1,3-Dienes with Aminals
palladium‐catalyzed selective aminomethylation of conjugated 1,3‐dienes with aminals via double C—N bond activation is described. This simple method provides an effective and rapid approach for the synthesis of linear α,β‐unsaturated allylic amines with perfect regioselectivity. Mechanistic studies disclosed that one palladium catalyst cleaved two distinct C—N bond to furnish a cascade double C—N bond activation
Silver-Catalyzed <i>anti</i>-Markovnikov Hydroboration of C–C Multiple Bonds
作者:Yan Wang、Rui Guan、Paramasivam Sivaguru、Xuefeng Cong、Xihe Bi
DOI:10.1021/acs.orglett.9b01217
日期:2019.6.7
simple silver salt (AgOAc)-catalyzed anti-Markovnikov-selective hydroboration of alkenes, 1,3-dienes, and alkynes with pinacolborane (HBpin) has been described. This strategy provides an efficient and practical method to access various alkyl-, allyl-, and (E)-alkenylboronate esters in good to excellent yields with regio- and stereoselectivity under ligand- and base-free conditions.