High‐Loading Single‐Atom Copper Catalyst Supported on Coordinatively Unsaturated Al
<sub>2</sub>
O
<sub>3</sub>
for Selective Synthesis of Homoallylboronates
Single‐atom catalysts (SACs) as a bridge between hetero‐ and homogeneouscatalysis have attracted much attention. However, it is still challenging to generate stable single atoms with high metal loadings, and the application of SACs in traditionally homogeneous catalytic reactions is highly desirable. Herein, a Cu SAC with a high Cu loading of 8.7 wt % supported on coordinatively unsaturated Al2O3
作为杂化和均相催化之间桥梁的单原子催化剂(SAC)引起了广泛关注。然而,产生具有高金属负载量的稳定的单原子仍然具有挑战性,并且非常需要在传统的均相催化反应中使用SAC。在此,制备了负载在配位不饱和Al 2 O 3上的担载量为8.7 wt%的高Cu含量的Cu SAC,并将其用于无胺合成高烯丙烷。达到了高达99%的转化率,95%的1,4-选择硼酸烯丙基化和48-68%的均烯丙基异丁烯分离产率,与报道的均相催化剂的结果相当,而且该系统比纳米Cu /更高效,更稳定。 γ‐Al 2 O 3。机理研究表明,Cu-Bpin物种是选择性硼酸化的活性中间体。Cu SAC优异的催化和再循环性能为选择合成高烯丙基硼烷精细化学品铺平了一条高效而绿色的道路。
Catalytic Asymmetric Synthesis of α-Alkylidene-β-hydroxy Esters via Dynamic Kinetic Asymmetric Transformation Involving Ba-Catalyzed Direct Aldol Reaction
A Ba-catalyzed dynamickineticasymmetrictransformation (DYKAT) involving a direct aldol/retro-aldol reaction of beta,gamma-unsaturated ester donors is described. A Ba(O-iPr)(2)/BINOL complex promoted the direct aldol reaction/isomerization sequence, and alpha-alkylidene-beta-hydroxy esters were obtained from aryl, heteroaryl, alkenyl, and alkyl aldehydes under simple proton-transfer conditions with
介绍了 Ba 催化的动态动力学不对称转化 (DYKAT),涉及 β、γ-不饱和酯供体的直接醇醛/逆醇醛反应。Ba(O-iPr)(2)/BINOL 复合物促进了直接的羟醛反应/异构化序列,并且在简单的质子转移条件下从芳基、杂芳基、烯基和烷基醛中获得了 α-亚烷基-β-羟基酯99-87% ee 和 >20:1 至 15:1 α/γ 选择性。
OMe) and a substituted enolate chain between SiMe3 and various CuI complexes was examined. Reaction mechanisms pass through a cyclic transition state in which the reaction coordinate is associated with rotation of the SiMe3 moiety. The dependence of the thermodynamic and kinetic features on the nature of the active and ancillary ligands was examined. Formation of copper enolate is shown to be favored