三取代烯烃的立体选择性合成是有机化学中长期存在的挑战,因为三取代烯烃的 E 和 Z 异构体之间的能量差异很小(与 1,2-二取代烯烃相比)。1,1-二取代烯烃的过渡金属催化异构化可以作为三取代烯烃的替代方法,但由于与反应效率和立体选择性有关的问题,它仍然不发达。在这里,我们展示了一种新型钴催化剂可以克服这些挑战,为获得广泛的三取代烯烃提供有效和立体选择性的途径。该协议与单烯和二烯兼容,并表现出良好的官能团耐受性和可扩展性。而且,它已被证明是构建有机发光体和氘代三取代烯烃的有用工具。对该机制的初步研究表明,该反应涉及钴氢化物途径。该反应的高立体选择性归因于 π-π 堆积效应和底物和催化剂之间的空间位阻。
Oxidative Mizoroki-Heck-Type Reaction of Arylsulfonyl Hydrazides for a Highly Regio- and Stereoselective Synthesis of Polysubstituted Alkenes
作者:Fu-Lai Yang、Xian-Tao Ma、Shi-Kai Tian
DOI:10.1002/chem.201103671
日期:2012.2.6
hydrazides have been identified as synthetically useful aryl sources for the Pd(OAc)2 catalyzed oxidative Mizoroki–Heck‐type reaction under molecular oxygen to provide a convenient access to polysubstituted alkenes in a highly regio‐ and stereoselective manner (see scheme). The reaction well tolerates various functional groups such as alkoxy, halo, alcohol, carboxylic acid, ester, amide, sulfonamide, and
Supported Au nanoparticles on TiO2 catalyze the unprecedented dehydrogenative disilylation of monosubstituted and 1,1‐disubstituted allenes by Et2SiH2 exclusively on the terminal double bond in a stereoselective manner. Treatment of the disilylation products with H2O, in a one‐pot operation also catalyzed by Au/TiO2, leads to 3‐alkylidene‐1,2,5‐oxadisilolanes, an unknown class of heterocyclic compounds
在TiO支持的Au纳米颗粒2催化单取代和1,1-二取代的丙二烯的前所未有脱氢disilylation通过的Et 2的SiH 2只在以立体选择性方式的末端双键。在同样由Au / TiO 2催化的一锅操作中,用H 2 O处理二烯丙基化产物会生成3-亚烷基-1,2,5-恶二硅环酮,这是一类未知的杂环化合物,是出色的支架Hiyama型交叉偶联条件下烯烃的立体选择性合成。
Hemilabile P,N-Ligand-Assisted Gold-Catalyzed Heck Reaction of Aryl and Styryl Iodides with Styrenes
作者:Cunbo Wei、Lizhu Zhang、Zhonghua Xia
DOI:10.1021/acs.orglett.3c02244
日期:2023.9.22
Heck reaction of aryl and styryl iodides with styrenes was developed. The hemilabile P,N-ligand-assisted gold-catalyzed C(sp2)–C(sp2) cross-coupling can synthesize stilbenes and bistyryl complexes, with good functional-group tolerance and mild conditions. The elementary organometallic steps of migratory insertion and β-hydride elimination might be involved in this ligand-enabled Au(I)/Au(III)-catalyzed