Chelate Restrained Boron Cations for Intermolecular Electrophilic Arene Borylation
Chelate Restrained Boron Cations for Intermolecular Electrophilic Arene Borylation
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DOI：
10.1021/om900893g
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发表时间：
2010-01-11
期刊：
影响因子：
2.8
通讯作者：
Ingleson, Michael J.
中科院分区：
文献类型：
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作者：
Del Grosso, Alessandro;Pritchard, Robin G.;Ingleson, Michael J.
通过[Et 3Si][CbBr 6（CbBr 6 = [closo-1-H-CB 11 H5 Br 6]（-））从CatBX（Cat =邻苯二酚根合物，C6 H4 O22-，X = Cl或Br）中提取卤化物来产生硼化芳烃的高度亲电硼物种。在分子间亲电硼化反应中，瞬时[CatB][CbBr 6]相关物质作为[CatB]（+）的合成等价物反应，反应在25 ℃下快速进行。根据巴豆醛和三乙基氧化膦加合物的H-1和P-31{H-1} NMR光谱，[CatB]（+）部分显示为强刘易斯酸性。催化量的[Et 3Si][CbBr 6]和CatBX对于CatBH在高原子效率循环中的芳烃硼化反应是有效的，其中H-2是唯一的副产物。成功的催化依赖于强[CbBr 6]（-）阴离子和使用亲电体抗性硼烷源，
Highly electrophilic boron species that borylate arenes are generated by halide abstraction from CatBX (Cat = catecholato, C6H4O22-, X = Cl or Br) by [Et3Si][CbBr6 (CbBr6 = [closo-1-H-CB11H5Br6](-)). A transient [CatB][CbBr6] related species reacts as a synthetic equivalent of [CatB](+) in intermolecular electrophilic borylation, with reactions proceeding rapidly at 25 degrees C. The [CatB](+) moiety was shown to be strongly Lewis acidic on the basis of H-1 and P-31{H-1} NMR spectroscopy of the crotonaldehyde and triethylphosphine oxide adducts, respectively. Catalytic quantities of [Et3Si][CbBr6] and CatBX were effective for the high-yielding borylation of arenes by CatBH in a highly atom efficient cycle with H-2 the only byproduct. Successful catalysis was dependent on the robust [CbBr6](-) anion and the use of electrophile-resistant borane sources,