Developments of Direct Synthesis and New Catalytic Reactions of Aromatic Boron Compounds

在1/2[Ir(OMe)(COD)]_2与4，4‘-二叔丁基-2，2’-联吡啶在正己烷中生成的Ir络合物催化下，芳烃和杂芳烃的芳香族和杂芳烃的C-H硼基化反应具有良好的区域选择性和高产率。这些反应可以容忍各种官能团，如卤素、羰基、氰基或苄基C-H键。反应机理可以包括通过Ir络合物与双(频那多)二硼或频那多硼烷反应生成三(硼基)Ir(III)络合物，将芳香族C-H键氧化加成到三(硼基)Ir(III)络合物上，以及还原消除芳香硼化合物。顺序反应，包括Ir催化的芳香族C-H硼化反应和钯催化的与芳香卤化物的交叉偶联反应，提供了一种…Pd(Dppe)(PHCN)_2[Pd(Dppe)(PHCN)_2](SbF_6)_2等阳离子钯(Ⅱ)络合物催化芳香硼化合物与烯酮的1，4-加成反应。提出了一个催化循环，包括芳香族硼化合物和阳离子钯配合物之间的转金属化反应，得到阳离子芳基钯(II)中间体，将烯酮插入碳-钯键，得到钯的烯醇化，最后用水水解，重新形成阳离子钯物种。在手性膦-阳离子钯(II)催化剂存在下，不对称反应在甲醇水溶液中进行。(S，S)-DIPAMP的钯配合物使β-芳基酮的光学活性高达96%ee，生成2-环己酮和2-环庚烯酮。钯-(S，S)-手性络合物对2-环戊酮和无环酮的ee为82-97%。较少

1.Iridium-Catalyzed Aromatic C-H BorylationAromatic C-H borylation of arenes and heteroarenes using stoichiometric amounts of bis(pinacolate)diboron or pinacolborane was catalyzed by an iridium complex generated from 1/2[Ir(OMe)(COD)]_2 and 4,4'-di-tert-butyl-2,2'-bipyridine at room temperature in hexane and afforded the corresponding aromatic and heteroaromatic boron compounds in high yields with excellent regioselectivities. The reactions tolerated various functionalities such as halogen, carbonyl, and cyano groups or benzylic C-H bonds. A reaction mechanism may involve generation of a tris(boryl)iridium(III) complex by the reaction of an iridium(I) complex with bis(pinacolato)diboron or pinacolborane, oxidative addition of an aromatic C-H bond to the tris(boryl)iridium(III) complex, and reductive elimination of an aromatic boron compound. Sequential reactions, involving iridium-catalyzed aromatic C-H borylation and palladium-catalyzed cross-coupling with aromatic halides, provided a … More one-pot procedure for the synthesis of various unsymmetrical biaryls.2.Palladium-Catalyzed 1,4-Addition of Aromatic Boron Compounds to Enones1,4-Addition of aromatic boron compounds to cyclic and acyclic enones was catalyzed by dicationic palladium(II) complexes such as [Pd(dppe)(PhCN)_2](SbF_6)_2 and nitrile free complexes. A catalytic cycle involving transmetalation between an aromatic boron compound and a dicationic palladium complex to give a cationic arylpalladium(II) intermediate, insertion of an enone into a carbon-palladium bond, giving a palladium enolate, and finally hydrolysis with water to regenetrate the dicationic palladium species was proposed. Asymmetric reactions were carried out in aqueous methanol in the presence of a chiral phosphine-dicationic palladium(II) catalyst. A palladium complex of (S,S)-dipamp gave optically active β-arylketones up to 96% ee for 2-cyclohexenone and 2-cycloheptenone. A palladium-(S,S)-chiraphos complex resulted in 82-97% ee for 2-cyclopentenone and acyclic ketones. Less