- A Dichotomy in Cross-Coupling Site Selectivity in a Dihalogenated Heteroarene: Influence of Mononuclear Pd, Pd Clusters, and Pd Nanoparticles-The Case for Exploiting Pd Catalyst Speciation
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Site-selective dihalogenated heteroarene cross-coupling with organometallic reagents usually occurs at the halogen proximal to the heteroatom, enabled by intrinsic relative electrophilicity, particularly in strongly polarized systems. An archetypical exam
- Eyles, Anthony,Fairlamb, Ian J. S.,Ford, Mark J.,Jeddi, Neda,Scott, Neil W. J.,Simon, Lauriane,Tanner, Theo,Whitwood, Adrian C.,Willans, Charlotte E.
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supporting information
p. 9682 - 9693
(2021/07/19)
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- Selective Halogenation of Pyridines Using Designed Phosphine Reagents
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Halopyridines are key building blocks for synthesizing pharmaceuticals, agrochemicals, and ligands for metal complexes, but strategies to selectively halogenate pyridine C-H precursors are lacking. We designed a set of heterocyclic phosphines that are installed at the 4-position of pyridines as phosphonium salts and then displaced with halide nucleophiles. A broad range of unactivated pyridines can be halogenated, and the method is viable for late-stage halogenation of complex pharmaceuticals. Computational studies indicate that C-halogen bond formation occurs via an SNAr pathway, and phosphine elimination is the rate-determining step. Steric interactions during C-P bond cleavage account for differences in reactivity between 2- and 3-substituted pyridines.
- Alegre-Requena, Juan V.,Levy, Jeffrey N.,Liu, Renrong,McNally, Andrew,Paton, Robert S.
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supporting information
p. 11295 - 11305
(2020/07/13)
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- Transition-Metal-Free Decarboxylative Arylation of 2-Picolinic Acids with Arenes under Air Conditions
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A facile, transition-metal-free, and direct decarboxylative arylation of 2-picolinic acids with simple arenes is described. The oxidative decarboxylative arylation of 2-picolinic acids with arenes proceeds readily via N-chloro carbene intermediates to afford 2-arylpyridines in satisfactory to good yields under transition-metal-free conditions. This new type of decarboxylative arylation is operationally simple and scalable and exhibits high functional-group tolerance. Various synthetically useful functional groups, such as halogen atoms, methoxycarbonyl, and nitro, remain intact during the decarboxylative arylation of 2-picolinic acids.
- Zhang, Xitao,Feng, Xiujuan,Zhou, Chuancheng,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
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supporting information
p. 7095 - 7099
(2018/11/23)
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- METAL COMPLEX AND ORGANIC LIGHT-EMITTING DEVICE
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A metal complex of formula (I): M(L1)x(L2)y (I) wherein: M is a second or third row transition metal; L1 in each occurrence is independently a light-emitting ligand; L2 is an auxiliary ligand; x is at least 1; y
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Page/Page column 33; 34
(2017/01/09)
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- Triarylbismuthanes as threefold aryl-transfer reagents in regioselective cross-coupling reactions with bromopyridines and quinolines
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Cross-coupling studies using bromopyridines and bromoquinolines with triarylbismuths as threefold coupling reagents in substoichiometric amounts under Pd-catalysed conditions are disclosed. The reactivity was high with both mono- and dibromopyridyl substrates, and mono- and bis-couplings were carried out regioselectively. A library of monoaryl and diaryl pyridines was formed in high yields. A one-pot strategy provided a simple and straightforward synthesis of both symmetrical and unsymmetrical diarylpyridines. Arylations of 2-bromo- and 3-bromoquinolines were achieved with triarylbismuth reagents. This study demonstrates that triarylbismuths may be used as threefold arylating reagents for the synthesis of aryl pyridines and quinolines through couplings with bromopyridines and bromoquinolines under Pd-catalysed conditions. Copyright
- Rao, Maddali L.N.,Dhanorkar, Ritesh J.
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p. 5214 - 5228
(2014/10/15)
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- Palladium-catalyzed highly regioselective 2-arylation of 2,x-dibromopyridines and its application in the efficient synthesis of a 17β-HSD1 inhibitor
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2,3- and 2,5-Dibromopyridines reacted with arylboronic acids, catalyzed by Pd(OAc)2/PPh3 in the presence of K2CO 3 in CH3CN/MeOH (2:1) at 50 C for 24 h, to afford 2-arylpyridines in good to high yield
- Zhou, Qizhong,Zhang, Bin,Su, Liangjun,Jiang, Tiansheng,Chen, Rener,Du, Tieqi,Ye, Yuyuan,Shen, Jianfen,Dai, Guoliang,Han, Deman,Jiang, Huajiang
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p. 10996 - 11003
(2014/01/06)
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- Regioselectivity in alkenyl(aryl)-heteroaryl Suzuki cross-coupling reactions of 2,4-dibromopyridine. A?synthetic and mechanistic study
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2,4-Dibromopyridine undergoes a regioselective Suzuki cross-coupling reaction at position 2 with several alkenyl(aryl) boronic acids to render 4-bromo-2-carbon substituted pyridines, difficult to be prepared otherwise, in good yields under palladium catal
- Sicre, Cristina,Alonso-Gómez, J.-Lorenzo,Cid, M. Magdalena
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p. 11063 - 11072
(2007/10/03)
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- Synthesis of atropisomeric 1,8-bis(4′,4′-dipyridyl)naphthalenes from 4-trimethylstannylpyridines
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Two synthetic strategies towards atropisomeric 2′,2′-disubstituted 1,8-bis(4′,4′-dipyridyl)naphthalenes using Stille crosscoupling of trimethylstannylpyridine derivatives and 1,8-di-iodonaphthalene have been investigated. Introduction of substituents into the pyridyl moieties prior to the cross-coupling step provides higher overall yields than derivatization of 1,8-bis(4′,4′-dipyridyl)naphthalene under Ziegler reaction conditions.
- Wolf, Christian,Ghebremariam, Bereket T.
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p. 749 - 752
(2007/10/03)
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