Mechanism of the mild functionalization of arenes by diboron reagents catalyzed by iridium complexes. Intermediacy and chemistry of bipyridine-ligated iridium trisboryl complexes

被引:450
作者
Boller, TM
Murphy, JM
Hapke, M
Ishiyama, T
Miyaura, N
Hartwig, JF
机构
[1] Yale Univ, Dept Chem, New Haven, CT 06520 USA
[2] Hokkaido Univ, Grad Sch Engn, Div Chem Proc Engn, Sapporo, Hokkaido 0608628, Japan
关键词
D O I
10.1021/ja053433g
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
This paper describes mechanistic studies on the functionalization of arenes with the diboron reagent B(2)pin(2) (bis-pinacolato diborane(4)) catalyzed by the combination of 4,4'-di-tert-butylbipyridine (dtbpy) and olefin-ligated iridium halide or olefin-ligated iridium alkoxide complexes. This work identifies the catalyst resting state as [Ir(dtbpy)(COE)(Bpin)(3)] (COE = cyclooctene, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaborolanyl). [Ir(dtbpy)(COE)(Bpin)(3)] was prepared by independent synthesis in high yield from [Ir(COD)(OMe)](2), dtbpy, COE, and HBpin. This complex is formed in low yield from [lr(COD)(OMe)](2), dtbpy, COE, and B2pin2. Kinetic studies show that this complex reacts with arenas after reversible dissociation of COE. An alternative mechanism in which the arene reacts with the lr(l) complex [Ir(dtbpy)Bpin] after dissociation of COE and reductive elimination of B(2)pin(2) does not occur to a measurable extent. The reaction of [Ir(dtbpy)(COE)(Bpin)(3)] with arenes and the catalytic reaction of B(2)pin(2) with arenes catalyzed by [lr(COD)(OMe)](2) and dtbpy occur faster with electron-poor arenas than with electron-rich arenes. However, both the stoichiometric and catalytic reactions also occur faster with the electron-rich heteroarenes thiophene and furan than with arenes, perhaps because eta(2)-heteroarene complexes are more stable than the eta(2)-arene complexes and the eta(2)-heteroarene or arene complexes are intermediates that precede oxidative addition. Kinetic studies on the catalytic reaction show that [lr(dtbpy)(COE)(Bpin)(3)] enters the catalytic cycle by dissociation of COE, and a comparison of the kinetic isotope effects of the catalytic and stoichiometric reactions shows that the reactive intermediate [lr(dtbpy)(Bpin)(3)] cleaves the arene C-H bond. The barriers for ligand exchange and C-H activation allow an experimental assessment of several conclusions drawn from computational work, Most generally, our results corroborate the conclusion that C-H bond cleavage is turnover-limiting, but the experimental barrier for this bond cleavage is much lower than the calculated barrier.
引用
收藏
页码:14263 / 14278
页数:16
相关论文
共 63 条
[1]   UNUSUALLY MILD AND SELECTIVE HYDROCARBON C-H BOND ACTIVATION WITH POSITIVELY CHARGED IRIDIUM(III) COMPLEXES [J].
ARNDTSEN, BA ;
BERGMAN, RG .
SCIENCE, 1995, 270 (5244) :1970-1973
[2]   OBSERVATIONS ON CONVERSION OF ACETONE INTO PINACOL HYDRATE BY MAGNESIUM AMALGAM [J].
BINKS, J ;
LLOYD, D .
JOURNAL OF THE CHEMICAL SOCIETY C-ORGANIC, 1971, (15) :2641-&
[3]   THE SYNTHESIS OF 1-METHYL-1-GERMAADAMANTANE [J].
BOUDJOUK, P ;
KAPFER, CA .
JOURNAL OF ORGANOMETALLIC CHEMISTRY, 1985, 296 (03) :339-349
[4]  
Chen HY, 1999, ANGEW CHEM INT EDIT, V38, P3391, DOI 10.1002/(SICI)1521-3773(19991115)38:22<3391::AID-ANIE3391>3.0.CO
[5]  
2-N
[6]   Thermal, catalytic, regiospecific functionalization of alkanes [J].
Chen, HY ;
Schlecht, S ;
Semple, TC ;
Hartwig, JF .
SCIENCE, 2000, 287 (5460) :1995-1997
[7]   CONTROL OF ETA(2)-COORDINATION VS C-H BOND ACTIVATION BY RHODIUM - THE ROLE OF AROMATIC RESONANCE ENERGIES [J].
CHIN, RM ;
DONG, LZ ;
DUCKETT, SB ;
PARTRIDGE, MG ;
JONES, WD ;
PERUTZ, RN .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1993, 115 (17) :7685-7695
[8]   Remarkably selective iridium catalysts for the elaboration of aromatic C-H bonds [J].
Cho, JY ;
Tse, MK ;
Holmes, D ;
Maleczka, RE ;
Smith, MR .
SCIENCE, 2002, 295 (5553) :305-308
[9]   Steric and chelate directing effects in aromatic borylation [J].
Cho, JY ;
Iverson, CN ;
Smith, MR .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2000, 122 (51) :12868-12869
[10]   1:1 Adducts of 4-picoline with methylcatecholborane and phenylcatecholborane [J].
Clegg, W ;
Scott, AJ ;
Souza, FES ;
Marder, TB .
ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS, 1999, 55 :1885-1888