An efficient and practical protocol for the enantioselective cobalt‐catalyzed hydrovinylation of vinylarenes with ethylene at low (1.2 bar) pressure has been developed. As precatalysts, stable [L2CoCl2] complexes are employed that are activated in situ with Et2AlCl. A modular chiral TADDOL‐derived phosphine–phosphite ligand was identified that allows the conversion of a broad spectrum of substrates
Lewis-Acid-Catalyzed Rearrangement of Arylvinylidenecyclopropanes: Significant Influence of Substituents and Electronic Nature of Aryl Groups
作者:Yun-Peng Zhang、Jian-Mei Lu、Guang-Cai Xu、Min Shi
DOI:10.1021/jo061899r
日期:2007.1.1
reactions of arylvinylidenecyclopropanes having three substituents at the corresponding cyclopropyl rings have been investigated thoroughly. The reaction products are highly dependent on the substituents at the corresponding cyclopropyl rings and the electronic nature of the aryl groups. For arylvinylidenecyclopropanes bearing two alkyl groups at the C-1 position (R1, R2, R3 = aryl; R4 = H; R5, R6
路易斯酸催化的在相应的环丙基环上具有三个取代基的芳基亚乙烯基环丙烷的反应已被彻底研究。反应产物高度依赖于相应环丙基环上的取代基和芳基的电子性质。对于在C-1位带有两个烷基的芳基亚乙烯基环丙烷(R 1,R 2,R 3=芳基; R 4= H; R 5,R 6=烷基),在路易斯酸Eu存在下形成萘衍生物。 (OTf)3在40°C的DCE中。对于其中R 1,R 2,R 3的芳基亚乙烯基环丙烷=芳基和R 4,R 5=烷基(顺/反异构体混合物),当所有芳基均通过双分子内Friedel-Crafts反应以顺式构型形成相应的6a H-苯并[ c ]氟衍生物。不具有吸电子基团或通过分子内的Friedel-Crafts反应获得相应的茚衍生物,只要连接一个缺电子的芳基即可。对于其中R 1,R 2,R 3,R 4 =芳基和R 5的芳基亚乙烯基环丙烷=烷基或H,相应的茚衍生物仅通过空间上要求的分子内Friedel-C
Cobalt-Catalyzed Enantioconvergent Hydrogenation of Minimally Functionalized Isomeric Olefins
作者:Peng Lu、Hongliang Wang、Yihui Mao、Xin Hong、Zhan Lu
DOI:10.1021/jacs.2c08525
日期:2022.9.28
established methods often require geometrically pure olefins. The enantioconvergent reaction provided the possibility to access a single stereoisomer via hydrogenation of E/Z-olefin mixtures; however, a polar functional group next to the carbon–carbon double bond was usually necessary. Here, we reported a cobalt-catalyzed enantioconvergent hydrogenation of readily available minimally functionalized E/Z-olefin
由于对映体纯化合物的高需求,烯烃不对称氢化的研究在药物分子合成和化学工业中都具有重要意义。已建立的方法通常需要几何纯烯烃。对映收敛反应提供了通过氢化E / Z -烯烃混合物获得单一立体异构体的可能性;然而,通常需要在碳-碳双键旁边的极性官能团。在这里,我们报道了一种钴催化的对映收敛氢化容易获得的最小官能化E / Z-烯烃混合物。该策略显示出良好的官能团耐受性,并为对映收敛转化提供了一种替代方法。初步机理研究表明,钴催化异构化是实现收敛转化的关键。
Converging Stereodivergent Reactions: Highly Stereoselective Formal<i>anti</i>‐Markovnikov Addition of H<sub>2</sub>O to Mixtures of Olefins
A formal, two-step anti-Markovnikov addition of H2O to diastereomeric mixtures of trisubstituted olefins towards enantio- and diastereomerically highly-enriched alcohols is demonstrated. This method relies on the syn-specific Shi-epoxidation, followed by a titanocene-catalyzed epoxide hydrosilylation featuring a directional-isomerization step to converge the diastereomeric mixtures of epoxides into
证明了H 2 O 向三取代烯烃的非对映体混合物中向对映体和非对映体高度富集的醇进行正式的两步反马尔可夫尼科夫加成。该方法依赖于顺式特定的Shi环氧化,然后是二茂钛催化的环氧化物氢化硅烷化,其特征在于定向异构化步骤,将环氧化物的非对映异构体混合物聚合成单一立体异构体。
Highly Enantioselective and <i>Anti</i>-Diastereoselective Catalytic Intermolecular Glyoxylate–Ene Reactions: Effect of the Geometrical Isomers of Alkenes
An efficient method for the synthesis of homoallylic alcohols with high enantioselectivities and anti-diastereoselectivities via an In(III)-catalyzed intermolecular glyoxylateene reaction has been developed. The geometrical isomers of alkenes were shown to have different reactivities. Only the isomers of the alkenes having a proton beta-cis to the substituent reacted in this catalytic system.