- Diisopropylamide and TMP turbo-grignard reagents: A structural rationale for their contrasting reactivities
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(Figure Presented) Turbocharged! A neutral dimeric molecule in crystal form, the diisopropylamido turbo-Grignard reagent (iPr2N) MgCI· LiCl (see structure; blue N, red O, green Mg, yellow Cl, black C) separates into several charged ate species in dynamic exchange with each other in THF solution as determined by a combination of EXSY and DOSY NMR studies.
- Armstrong, David R.,Garcia-Alvarez, Pablo,Kennedy, Alan R.,Mulvey, Robert E.,Parkinson, John A.
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- Solution Structure of Turbo-Hauser Base TMPMgCl?LiCl in [D8]THF
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Turbo-Hauser bases are very useful and highly reactive organometallic reagents in synthesis. Especially TMPMgCl?LiCl 1 (TMP=2,2,6,6-tetramethylpiperidide) is an excellent base for converting a wide range of (hetero)aromatic substrates into highly function
- Neufeld, Roman,Stalke, Dietmar
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- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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p. 5022 - 5037
(2021/05/04)
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- Amide Effects in C?H Activation: Noncovalent Interactions with L-Shaped Ligand for meta Borylation of Aromatic Amides
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A new concept for the meta-selective borylation of aromatic amides is described. It has been demonstrated that while esters gave para borylations, amides lead to meta borylations. For achieving high meta selectivity, an L-shaped bifunctional ligand has been employed and engages in an O???K noncovalent interaction with the oxygen atom of the moderately distorted amide carbonyl group. This interaction provides exceptional control for meta C?H activation/borylation.
- Bisht, Ranjana,Hoque, Md Emdadul,Chattopadhyay, Buddhadeb
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p. 15762 - 15766
(2018/11/10)
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- Ruthenium-catalyzed ortho-C-H halogenations of benzamides
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[Ru3(CO)12] and AgO2C(1-Ad) enabled the first ruthenium-catalyzed intermolecular halogenations of arenes via C-H activation. Thereby, brominations and iodinations of electron-rich and electron-deficient benzamides were ach
- Wang, Lianhui,Ackermann, Lutz
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supporting information
p. 1083 - 1085
(2014/01/17)
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- Generation of an aromatic amide-derived phosphane (Aphos) library by self-assisted molecular editing and applications of Aphos in room-temperature Suzuki-Miyaura reactions
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Aromatic amide-derived phosphanes (Aphos) are hemilabile P,O-coordinating ligands, which, when combined with a Pd precursor, yield a promising precatalyst system for Suzuki-Miyaura cross-coupling reactions. A focused library of Aphos ligands has been constructed for structural optimization, with the target of improving catalytic efficacy. By using microwave irradiation at accurately regulated temperature, an expeditious and reproducible one-pot synthesis and screening protocol was designed and experimentally validated. The success is based on a unique self-assisted molecular editing (SAME) process in which both the substrate and the product molecules catalyze formation of the product. Thus, starting from a 4-chlorobenzamide-derived Aphos as the substrate, parallel reactions with a selected set of arylboronic acids, in the absence of an added external phosphane ligand to Pd, produced a family of structurally edited Aphos ligands. The resultant reaction mixture containing the new Aphos, the Pd species, and the base could be used for in situ screening of the Aphos efficacy in a reference Suzuki-Miyaura coupling reaction. The structures of all Aphos ligands were characterized by 31P NMR spectroscopy and their catalytic profiles in the reference reaction were evaluated by HPLC analysis. These data allowed the identification of an efficient Aphos ligand, capable of promoting room-temperature Suzuki-Miyaura coupling of unactivated and sterically hindered aryl chlorides with arylboronic acids under mildly basic conditions.
- Dai, Wei-Min,Li, Yannian,Zhang, Ye,Yue, Congyong,Wu, Jinlong
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supporting information; experimental part
p. 5538 - 5554
(2009/05/30)
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- The halogenation of some benzamides takes place preferentially at the ortho,para positions
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The orientation of chlorination and bromination of N,N-disubstituted benzamides in aqueous acetic acid is strongly influenced by the nature of the alkyl groups at the nitrogen atom. With large groups, the halogenation takes place fairly selectively at the ortho/para positions.
- Dong, Chang-Zhi,Julia, Marc,Tang, Jie
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p. 1689 - 1696
(2007/10/03)
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