- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
- Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
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p. 4622 - 4627
(2018/05/22)
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- Nickel-catalyzed cross-coupling of aldehydes with aryl halides: Via hydrazone intermediates
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Traditional cross-couplings require stoichiometric organometallic reagents. A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed, merging the Wolff-Kishner reduction and the classical cross-coupling reactions. Aromatic aldehydes, aryl iodides and aryl bromides are especially effective in this new cross-coupling chemistry.
- Tang, Jianting,Lv, Leiyang,Dai, Xi-Jie,Li, Chen-Chen,Li, Lu,Li, Chao-Jun
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p. 1750 - 1753
(2018/02/21)
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- Transition-Metal-Free Synthesis of Biarylmethanes from Aryl Iodides and Benzylic Ketones
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An original metal-free procedure for the synthesis of biarylmethanes is disclosed herein. The reactions occur with high selectivity starting from aryl iodides and benzylic ketones in the presence of superbasic media (CsOH/DMSO). This procedure allows a straightforward access to a wide range of biarylmethane derivatives substituted with electron-withdrawing and -donating substituents.
- Pichette Drapeau, Martin,Tlili, Anis,Zaid, Yassir,Toummini, Dounia,Ouazzani Chahdi, Fouad,Sotiropoulos, Jean-Marc,Ollevier, Thierry,Taillefer, Marc
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supporting information
p. 17449 - 17453
(2018/11/10)
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- Cobalt-Catalyzed Reductive Cross-Coupling Between Benzyl Chlorides and Aryl Halides
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A new protocol for the direct reductive cobalt-catalyzed arylation of benzyl chlorides has been developed in order to form functionalized diarylmethanes. A variety of reactive groups either on the aryl or the benzyl halide was employed. This represents the first cobalt-catalyzed reductive cross-coupling which does not require any ligand and pyridine. A reaction pathway is proposed involving a radical benzyl species. (Figure presented.).
- Pal, Suman,Chowdhury, Sushobhan,Rozwadowski, Elodie,Auffrant, Audrey,Gosmini, Corinne
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supporting information
p. 2431 - 2435
(2016/08/16)
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- Synthesis of diarylmethanes through palladium-catalyzed coupling of benzylic phosphates with arylsilanes
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An efficient approach to the benzylation of arenes has been developed. The reactions described provide straightforward access to diarylmethanes through Pd-catalyzed coupling of benzylic phosphates with arylsilanes in good to excellent yields. The reaction tolerates a wide range of functionalities such as halide, alkoxyl, and nitro groups.
- Zhang, Pengbo,Xu, Jian,Gao, Yuzhen,Li, Xueqin,Tang, Guo,Zhao, Yufen
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p. 2928 - 2932
(2015/01/16)
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- Iron-catalyzed hetero-cross-dehydrogenative coupling reactions of sulfoximines with diarylmethanes: A new route to N-alkylated sulfoximines
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An efficient iron-catalyzed C-N bond formation by hetero-cross- dehydrogenative coupling (CDC) between sulfoximines and diarylmethanes is described. The reaction shows good functional group tolerance and provides N-alkylated sulfoximines in moderate to go
- Cheng, Ying,Dong, Wanrong,Wang, Long,Parthasarathy, Kanniyappan,Bolm, Carsten
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supporting information
p. 2000 - 2002
(2014/05/06)
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- Simple mixed Fe-Zn catalysts for the Suzuki couplings of tetraarylborates with benzyl halides and 2-halopyridines
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Employing co-catalytic zinc reagents facilitates the iron-catalysed Suzuki cross-coupling of tetraarylborates with both benzyl and 2-heteroaryl halides.
- Bedford, Robin B.,Hall, Mark A.,Hodges, George R.,Huwe, Michael,Wilkinson, Mark C.
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supporting information; experimental part
p. 6430 - 6432
(2010/03/03)
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- Synthesis of diarylmethane derivatives from Pd-catalyzed cross-coupling reactions of benzylic halides with arylboronic acids
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A simple catalyst precursor prepared in situ from palladium acetate and triphenylphosphine shows high activity for the Suzuki cross-coupling reaction of benzylic bromides and chlorides with aryl boronic acids. The reaction can be carried out at low catalyst loading (0.002-1 mol%) and under mild conditions (room temperature to 80°C) furnishing diarylmethane derivatives in high yields (86-99%).
- Nobre, Sabrina M.,Monteiro, Adriano L.
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p. 8225 - 8228
(2007/10/03)
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- Hypophosphorous acid-iodine: A novel reducing system. Part 2: Reduction of benzhydrols to diarylmethylene derivatives
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A mixture of hypophosphorous acid (H3PO2) and iodine in acetic acid reduces a variety of substituted benzhydrols to the corresponding methylene derivatives in very high yields. The active reducing agent is hydrogen iodide generated by reaction between iodine and hypophosphorous acid.
- Gordon, Paul E.,Fry, Albert J.
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p. 831 - 833
(2007/10/03)
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- Ring-substituted histaprodifen analogues as partial agonists for histamine H1 receptors: Synthesis and structure-activity relationships
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Thirteen racemic benzene ring-substituted analogues of histaprodifen (8a; 2-[2-(3,3-diphenylpropyl)-1H-imidazol-4-yl]ethanamine), a novel lead for potent and selective histamine H1-receptor agonists, have been prepared from substituted 4,4-diphenylbutyronitriles 5 via cyclization of the corresponding methyl butyrimidates 6 with 2-oxo-4-phthalimido-1-butyl acetate in liquid ammonia, followed by deprotection. Nitriles 5 were accessible by alkylation of either substituted diphenylmethanes with 3-bromopropionitrile or diethyl malonate with substituted 1-chloro-diphenylmethanes and subsequent standard reactions. The title compounds 8 displayed partial agonism on conctractile H1 receptors of the guinea-pig ileum (E(max) = 2-98% relative to histamine) and, compared with the endogenous agonist, were endowed with agonist potencies of 4-92%. The meta fluorinated (8c) and meta chlorinated (8f) analogues showed the highest relative potency in this series (95% confidence limits 85-99% and 78-102%), but did not exceed the value of the lead 8a (99- 124%). Compound 8c (2-[2-[3-(3-fluorophenyl)-3-phenylpropyl]-1H-imidazol-4- yl]ethanamine) was a partial agonist at contractile H1 receptors of the guinea-pig aorta (relative potency 154% vs. 100% for histamine) and at relaxation-mediating endothelial H1 receptors of the rat aorta (relative potency 556% vs. 100% for histamine) and matched with the functional behaviour of 8a. Agonism observed for each compound was sensitive to blockade by the selective H1-receptor antagonist mepyramine (pA2 ? 9 (guinea-pig) and pA2 ? 8 (rat aorta)). All histaprodifen analogues 8 stimulated neither histaminergic H2/H3 nor cholinergic M3 receptors. They displayed only low to moderate affinity for these sites (H2: pD'2 3/M3: pA2 1-receptor agonist, viz. 2- phenylhistamine. (C) 2000 Editions scientifiques et medicales Elsevier SAS.
- Elz, Sigurd,Kramer, Kai,Leschke, Christian,Schunack, Walter
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