Rhodium Indenyl NHC and Fluorenyl-Tethered NHC Half-Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C-H Borylation of Arenes and Alkanes.
Rhodium Indenyl NHC and Fluorenyl-Tethered NHC Half-Sandwich Complexes: Synthesis, Structures and Applications in the Catalytic C-H Borylation of Arenes and Alkanes.
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hodenyl NHC和氟苯基螺旋的NHC半 - 桑德维奇复合物：竞技场和烷烃的催化C-H型体内的合成，结构和应用。
DOI：
10.1002/chem.202102961
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发表时间：
2021-12-20
影响因子：
4.3
通讯作者：
Mansell, Stephen M.
中科院分区：
文献类型：
--
作者：
Evans, Kieren J.;Morton, Paul A.;Luz, Christian;Miller, Callum;Raine, Olivia;Lynam, Jason M.;Mansell, Stephen M.
以1，3-二氢茚为原料，合成了茚基铑氮杂环卡宾配合物[Rh（η 5-Ind）（NHC）（L）]（2，6-二异丙基苯基）-4，5-二氢咪唑-2-亚基（SIPr），其中L= C2 H4（1），CO（2 a）和环辛烯（COE; 3），对于1，3之二（2，4，6-三甲基苯基）-4，5-二氢咪唑-2-亚基（SIMes），其中L=CO（2 B）和COE（4），以及1，3-双（2，4，6-三甲基苯基）咪唑-2-亚基（IMes），L=CO（2 c）和COE（5）。SIPr与[Rh（Cp*）（C2 H4）2]的反应没有得到所需的SIPr络合物，因此证明了1的合成中的“茚基效应”。HSi（OEt）_3与3在温和条件下进行氧化加成，得到Rh硅氢化物配合物[Rh（Ind）{Si（OEt）_3}（H）（SIPr）]（6），损失了COE。栓系芴基NHC铑配合物[Rh{（η 5-C13H8）C2H4N（C）C2H x NR}（L）]（x=4，R=Dipp，L=C2H4：11; L=COE：12; L=CO：13; R=Mes，L=COE：14; L=CO：15; x=2，R=Me，L=COE：16; L=CO：17）以较低的产率（5- 31%）合成，而单齿络合物的产率较高（49- 79%）。含有不稳定烯烃配体的化合物3和1是用于苯与B2 pin 2的催化硼基化的成功催化剂（Bpin=频哪醇硼酸酯，分别为97和93%PhBpin，5 mol %催化剂，24小时，80 °C），其中SIPr给出比SIMes或IMes更活性的催化剂。 芴基栓系的NHC络合物作为硼化催化剂的活性低得多，并且羰基络合物是无活性的。甲苯、联苯、苯甲醚和二苯醚的硼基化反应以Meta取代为主要产物，少量帕拉取代，几乎没有邻位产物。在120和140 °C下分别用B2 pin 2对辛烷和癸烷进行硼基化，通过11B NMR光谱进行监测，其显示在4-7天内向辛基和癸基Bpin的高转化率，从而证明了用新的钢琴凳铑茚基络合物催化的sp3 C-H硼基化。 用400或420 nm光照射单齿配合物证实了C2 H4和COE配体的容易解离，而CO配合物是惰性的。 获得了NHC配体的烷基中C-H键活化的证据。 具有不稳定烯烃配体（乙烯和环辛烯）的茚基铑NHC络合物已被合成，并且被证明是比相关芴基束缚的NHC铑络合物更好的催化剂，用于芳烃和烷烃的C-H活化和硼基化。
Indenyl (Ind) rhodium N‐heterocyclic carbene (NHC) complexes [Rh(η 5‐Ind)(NHC)(L)] were synthesised for 1,3‐bis(2,6‐diisopropylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIPr) with L=C2H4 (1), CO (2 a) and cyclooctene (COE; 3), for 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIMes) with L=CO (2 b) and COE (4), and 1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene (IMes) with L=CO (2 c) and COE (5). Reaction of SIPr with [Rh(Cp*)(C2H4)2] did not give the desired SIPr complex, thus demonstrating the “indenyl effect” in the synthesis of 1. Oxidative addition of HSi(OEt)3 to 3 proceeded under mild conditions to give the Rh silyl hydride complex [Rh(Ind){Si(OEt)3}(H)(SIPr)] (6) with loss of COE. Tethered‐fluorenyl NHC rhodium complexes [Rh{(η 5‐C13H8)C2H4N(C)C2H x NR}(L)] (x=4, R=Dipp, L=C2H4: 11; L=COE: 12; L=CO: 13; R=Mes, L=COE: 14; L=CO: 15; x=2, R=Me, L=COE: 16; L=CO: 17) were synthesised in low yields (5–31 %) in comparison to good yields for the monodentate complexes (49–79 %). Compounds 3 and 1, which contain labile alkene ligands, were successful catalysts for the catalytic borylation of benzene with B2pin2 (Bpin=pinacolboronate, 97 and 93 % PhBpin respectively with 5 mol % catalyst, 24 h, 80 °C), with SIPr giving a more active catalyst than SIMes or IMes. Fluorenyl‐tethered NHC complexes were much less active as borylation catalysts, and the carbonyl complexes were inactive. The borylation of toluene, biphenyl, anisole and diphenyl ether proceeded to give meta substitutions as the major product, with smaller amounts of para substitution and almost no ortho product. The borylation of octane and decane with B2pin2 at 120 and 140 °C, respectively, was monitored by 11B NMR spectroscopy, which showed high conversions into octyl and decylBpin over 4–7 days, thus demonstrating catalysed sp3 C−H borylation with new piano stool rhodium indenyl complexes. Irradiation of the monodentate complexes with 400 or 420 nm light confirmed the ready dissociation of C2H4 and COE ligands, whereas CO complexes were inert. Evidence for C−H bond activation in the alkyl groups of the NHC ligands was obtained. Indenyl rhodium NHC complexes with labile alkene ligands (ethene and cyclooctene) have been synthesized and shown to be better catalysts than the related fluorenyl‐tethered NHC rhodium complexes for the C−H activation and borylation of arenes and alkanes.
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影响因子：
56.9
作者：
Cook, Amanda K.;Schimler, Sydonie D.;Sanford, Melanie S.
通讯作者：
Sanford, Melanie S.
影响因子：
2.4
作者：
Adams, J;Kauffman, M
通讯作者：
Kauffman, M
影响因子：
56.9
作者：
Chen, HY;Schlecht, S;Hartwig, JF
通讯作者：
Hartwig, JF
DOI：
10.1039/c39890000928
发表时间：
1989-07-15
影响因子：
--
作者：
BELT, ST;DUCKETT, SB;PERUTZ, RN
通讯作者：
PERUTZ, RN
影响因子：
62.1
作者：
Colby, Denise A.;Bergman, Robert G.;Ellman, Jonathan A.
通讯作者：
Ellman, Jonathan A.