Palladium-Catalyzed Cross-Coupling Reaction of Heteroaryltriolborates with Aryl Halides for Synthesis of Biaryls.
Palladium-Catalyzed Cross-Coupling Reaction of Heteroaryltriolborates with Aryl Halides for Synthesis of Biaryls.
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DOI：
10.1002/chin.201021143
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
Yasunori Yamamoto;M. Takizawa;Xiao‐Qiang Yu;N. Miyaura
中科院分区：
文献类型：
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作者：
Yasunori Yamamoto;M. Takizawa;Xiao‐Qiang Yu;N. Miyaura
以杂芳基硼酸、1，1，1-三（羟甲基）乙烷（三醇）和KOH或NaH为原料，高产率地合成了硼原子上带有杂芳环的环状三醇硼酸酯[ArB（OCH 2）3CHCH 3] M（M=K，Na，Li）.以芳基锂、B（OMe）3和三元醇为原料合成了相应的锂盐。它们是空气稳定的白色固体，便于在空气中处理。在钯催化的卤代芳烃的交叉偶联反应中证明了这些三醇硼酸酯在金属催化的成键反应中的高性能。尽管使用杂芳基硼酸由于在使用碱水溶液的典型条件下与水竞争性水解B-C键裂解而通常导致非常低的产率，但具有2-吡啶基、3-吡啶基或2-噻吩基环的三醇硼酸酯在50-120 °C下在无水DMF中以高产率提供联芳基。CuI对2-和3-吡啶基硼酸酯衍生物的反应有很强的加速作用，而2-噻吩基衍生物在不存在CuI的情况下反应平稳，导致高产率。
Cyclic triolborates possessing a heteroaromatic ring on the boron atom [ArB(OCH 2 ) 3 CHCH 3] M (M=K, Na, Li) were prepared in high yields from heteroarylboronic acids, 1,1,1 -tris(hydroxymethyl)ethane (triol) and KOH or NaH. The corresponding lithium salts were synthesized from aryllithiums, B(OMe) 3 and triol. They were air-stable white solids that were convenient for handling in air. High performance of these triolborates for metal-catalyzed bond-forming reactions was demonstrated in palladium-catalyzed cross-coupling reactions with haloarenes. Although the use of heteroarylboronic acids often results in very low yields due to competitive hydrolytic B-C bond cleavage with water under typical conditions using aqueous bases, triolborates possessing a 2-pyridyl, 3-pyridyl or 2-thiophenyl ring afforded biaryls in high yields at 50-120 °C in anhydrous DMF. There was a strong accelerating effect of Cul for reactions of 2- and 3-pyridylborate derivatives, whereas 2-thiophenyl derivatives reacted smoothly resulting in high yields in the absence of Cul.