Synthesis of <i>Z</i>-(Pinacolato)allylboron and <i>Z</i>-(Pinacolato)alkenylboron Compounds through Stereoselective Catalytic Cross-Metathesis
作者:Elizabeth T. Kiesewetter、Robert V. O’Brien、Elsie C. Yu、Simon J. Meek、Richard R. Schrock、Amir H. Hoveyda
DOI:10.1021/ja403188t
日期:2013.4.24
first examples of catalytic cross-metathesis (CM) reactions that furnish Z-(pinacolato)allylboron and Z-(pinacolato)alkenylboron compounds are disclosed. Products are generated with high Z selectivity by the use of a W-based monoaryloxide pyrrolide (MAP) complex (up to 91% yield and >98:2 Z:E). The more sterically demanding Z-alkenylboron species are obtained in the presence of Mo-based MAP complexes
公开了提供Z-(频哪醇)烯基硼和Z-(频哪醇)烯基硼化合物的催化交叉复分解(CM)反应的第一实例。通过使用 W 基单芳氧基吡咯 (MAP) 络合物,生成具有高 Z 选择性的产品(产率高达 91%,Z:E >98:2)。在 Mo 基 MAP 配合物存在下,可以获得空间要求更高的 Z-烯基硼物质,产率高达 93%,Z 选择性高达 97%。首次报道了 1,3-二烯和芳基烯烃的 Z 选择性 CM。该方法与催化交叉偶联相结合的实用性通过抗癌剂考布他汀 A-4 的简洁和立体选择性合成得到了证明。
Z-Selective Alkyne Functionalization Catalyzed by a <i>trans</i>-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex
作者:Subhash Garhwal、Natalia Fridman、Graham de Ruiter
DOI:10.1021/acs.inorgchem.0c02057
日期:2020.10.5
The Z-selective functionalization of terminalalkynes is a useful transformation in organic chemistry and mainly catalyzed by noble metals. Here, we present the Z-selective hydroboration of terminalalkynes catalyzed by a stable trans-dihydride iron complex [(PCNHCP)Fe(H)2N2)] (2). Overall, the reaction occurs at room temperature and provides near quantitative yields of the Z-vinylboronate ester. Interestingly
末端炔烃的Z选择性官能化是有机化学中的有用转变,主要由贵金属催化。在这里,我们介绍了由稳定的反式-二酐铁络合物[(PC NHC P)Fe(H)2 N 2)](2)催化的末端炔烃的Z选择性氢硼化。总的来说,该反应在室温下发生,并提供接近定量的Z-乙烯基硼酸酯。有趣的是,相同的催化剂也可以提供E-在稍微升高的温度(50°C)下加热反应混合物,生成-乙烯基硼酸酯。但是,如果该反应是在不存在HBpin的情况下进行的,则会观察到快速的Z选择性炔烃二聚化,这将在本报告中进一步讨论。
Catalytic Non-Conventional trans-Hydroboration: A Theoretical and Experimental Perspective
作者:Jessica Cid、Jorge J. Carbó、Elena Fernández
DOI:10.1002/chem.201102729
日期:2012.1.27
four stages: 1) isomerization of the alkyne into the vinylidene, 2) oxidative addition of the borane reagent, 3) vinylidene insertion into the RhH bond, and finally 4) reductive elimination of the CB bond to yield the 1‐alkenylboronate. Calculations indicated that the vinylidene insertion is the selectivity‐determining step. This result was consistent with the observed Zselectivity when the sterically
Synthesis of cis-vinyltrimethylstannanes and cis-vinylpinacolboronates in a two-step highly regio and stereoselective process
作者:Paul Malek Mirzayans、Rebecca H. Pouwer、Craig M. Williams、Paul V. Bernhardt
DOI:10.1016/j.tet.2009.06.092
日期:2009.9
A highly efficient two-step regio and stereoselective method for the synthesis of both cis-vinyltrimethylstannanes and cis-vinylpinacolboronates is described. This method takes advantage of the known lithium/tellurium exchange pathway providing a versatile alternative to known literature methods The methodology presented demonstrates compatibility, for example, with substrates bearing oxygen functionality in comparison to previously reported methods of cis-selective hydrostannylation (i.e., ZrCl4) (C) 2009 Elsevier Ltd. All rights reserved