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。
Regioselective Diboron-Mediated Semireduction of Terminal Allenes
作者:Ashley M. Gates、Webster L. Santos
DOI:10.1055/s-0039-1690207
日期:2019.12
A method for the regioselective reduction of the terminaldoublebond of 1,1-disubstituted allenes has been developed. In the presence of a palladium catalyst, tetrahydroxydiboron and stoichiometric water, allene semireduction proceeds in high yield to afford Z-alkenes selectively.
The first transition metal-free highly stereoselective positional isomerization of various α-alkyl styrenes through a carbocation mechanism triggered strategy is developed by using Al(OTf)3 as a hidden Brønsted acid catalyst, which provides facile access to value-added acyclic tri- and tetra-substituted alkenes in good yields with high stereoselectivity under mild conditions. The practicality of this
Bupropion Metabolites and Methods of Their Synthesis and Use
申请人:FANG Kevin Qun
公开号:US20100125070A1
公开(公告)日:2010-05-20
Methods and compositions are disclosed which utilize metabolites of bupropion for treating disorders ameliorated by inhibition of neuronal monoamine reuptake. Such disorders include, but are not limited to, sexual dysfunction, affective disorders, cerebral function disorders, cigarette smoking, and incontinence. Methods of making optically pure bupropion metabolites are also disclosed.
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。
Cobalt-Catalyzed Migrational Isomerization of Styrenes
作者:Jiajin Zhao、Biao Cheng、Chenhui Chen、Zhan Lu
DOI:10.1021/acs.orglett.9b04305
日期:2020.2.7
An efficient cobalt-catalyzed migrational isomerization of styrenes was developed using the thiazoline iminopyridine (TIP) ligand. This reaction is operationally simple and atom economical using readily available starting materials to access trisubstituted alkenes. Even when using a 0.1 mol % catalyst loading, the reaction could be conducted in neat and completed in 1 h with excellent conversion and high E stereoselectivity.