Copper-Catalyzed Regioselective Formation of Tri- and Tetrasubstituted Vinylboronates in Air
Copper-Catalyzed Regioselective Formation of Tri- and Tetrasubstituted Vinylboronates in Air
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DOI：
10.1021/cs500130y
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发表时间：
2014-05-01
期刊：
影响因子：
12.9
通讯作者：
Cazin, Catherine S. J.
中科院分区：
文献类型：
--
作者：
Bidal, Yannick D.;Lazreg, Faima;Cazin, Catherine S. J.
首次提出了在空气中铜催化选择性合成三取代和四取代乙烯基硼酸酯衍生物的方法。描述了使用单一催化剂[Cu（Cl）（IMes）]（IMes = N，N '-双-[2，4，6-（三甲基）苯基]-咪唑-2-亚基）而不采取任何预防措施避免空气存在的内炔硼基化的三种不同变体（α-硼氢化、β-硼氢化和硼碳化）。在甲醇存在下，使用双（频哪醇合）二硼得到β-硼氢化产物。相反，添加另一种亲电试剂可以形成四取代乙烯基硼酸酯物质。最后，使用频哪醇硼烷作为硼源获得α-产物。在低催化剂负载量（0.04-2，mol %）下，所有化合物均以高收率和优异的区域选择性获得。该协议构成了一个非常方便的途径来访问这些非常有价值的分子。
The first "in air" copper-catalyzed method for the selective synthesis of tri- and tetrasubstituted vinylboronate derivatives is presented. Three different variants of the borylation of internal alkynes (alpha-hydroboration, beta-hydroboration, and carboboration) are described using a single catalyst: [Cu(Cl)(IMes)] (IMes = N,N'-bis-[2,4,6-(trimethyl)phenyl]-imidazol-2-ylidene) without taking any precaution to avoid the presence of air. Bis(pinacolato)diboron was used to afford beta-hydroborated products in the presence of methanol. Adding instead another electrophile allowed the formation of tetrasubstituted vinylboronate species. Finally, the alpha-products were obtained using pinacolborane as the boron source. All compounds were obtained in high yield with excellent regioselectivity at low catalyst loading (0.04-2, mol %). The protocol constitutes a very convenient route to access these highly valuable molecules.