Palladium-Catalyzed Direct Arylation of Azine and Azole <i>N</i>-Oxides: Reaction Development, Scope and Applications in Synthesis

Campeau, Louis‐Charles; Stuart, David R.; Leclerc, Jean‐Philippe; Bertrand-Laperle, Mégan; Villemure, Elisia; Sun, Ho‐Yan; Lasserre, Sandrine; Guimond, Nicolas; Lecavallier, Melanie; Fagnou, Keith

doi:10.1021/ja808332k

Cited by 401 publications

(179 citation statements)

References 88 publications

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“…For example, a series of protein kinase inhibitors [4] was synthesized by the so-called ''sulfur transfer reaction'' [5], whereas direct palladium-catalyzed arylation protocol opened up direct access to potent Tie2 tyrosine kinase inhibitor [6]. Special attention was paid to the synthesis of imidazole N-oxides with new substitution patterns, particularly the analogs lacking a substituent at carbon C(2) atom, and their transformations into more complex derivatives [5,[7][8][9]. A large number of key 2-unsubstituted N-oxides exhibit limited stability either under high temperature, UV irradiation or in the presence of acylating agents, and can undergo isomerization to the corresponding imidazol-2-ones.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent polymorphism of N-(4-fluorophenyl)-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide: experimental and theoretical studies on intermolecular interactions in the crystal state

et al. 2014

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X-ray analysis of N-(4-fluorophenyl)-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide reveals the temperature-dependent polymorphism associated with the crystallographic symmetry conversion. The observed crystal structure transformation corresponds to a symmetry reduction from I4 1 /a (I) to P4 3 (II) space groups. The phase transition mainly concerns the subtle but clearly noticeable reorganization of molecules in the crystal space, with the structure of individual molecules left almost unchanged. The Hirshfeld surface analysis shows that various intermolecular contacts play an important role in the crystal packing, revealing graphically the differences in spatial arrangements of the molecules in both polymorphs. The N-oxide oxygen atom acts as a formally negatively charged hydrogen bonding acceptor in intramolecular hydrogen bond of N-H…O -type. The combined crystallographic and theoretical DFT methods demonstrate that the observed intramolecular N-oxide N-H…O hydrogen bond should be classified as a very strong charge-assisted and closed-shell non-covalent interaction.

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Section: Introductionmentioning

confidence: 99%

Temperature-dependent polymorphism of N-(4-fluorophenyl)-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide: experimental and theoretical studies on intermolecular interactions in the crystal state

et al. 2014

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“…It is well documented that some imidazole derivatives such as imidazole N-oxides [2], imidazole-2-thiones [3] or 2-sulfanylimidazoles [4] show diverse biological activities. On the other hand, imidazole N-oxides were used for the preparation of more complex N-heterocles via Pd-catalyzed direct arylation [5], and in the case of optically active derivatives, they were applied as promising ligands for asymmetric allylation of aromatic aldehydes [6].…”

mentioning

confidence: 99%

Synthesis and Selected Reactions of Hydrazides Containing an Imidazole Moiety

Mlostoń

Pieczonka

Kowalczyk

et al. 2011

Helvetica Chimica Acta

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The preparation of two types of imidazole derivatives bearing a hydrazide group was achieved by treatment of the corresponding esters with NH2NH2·H2O in MeOH at room temperature. In the case of 4-(ethoxycarbonyl)-1H-imidazole 3-oxides 3, hydrazides of type 1 were formed with retention of the N-oxide structure (Scheme 1). Interestingly, due to a strong H-bonding, no deoxygenation of the N-O function could be achieved even by treatment of 3 with Raney-Ni. The second type, 2-[(1H-imidazol-2-yl)sulfanyl]acetohydrazides 2, was obtained from 1H-imidazole-2(3H)-thiones 4 in two steps via S-alkylation with methyl bromoacetate, followed by treatment with NH2NH2·H2O (Scheme 2). An imidazole 7, containing both types of hydrazide groups, was prepared analogously from ethyl 2,3-dihydro-2-thioxo-1H-imidazole-4-carboxylate 4d (Scheme 4). Both types of hydrazides, 1 and 2, were transformed successfully to the corresponding acylhydrazones 8 and 9, respectively (Scheme 5). Furthermore, it has been shown that hydrazides of type 1 are useful starting materials for the synthesis of 1,2,4-triazole-3-thiones 11 and 1,3,4-thiadiazole-2-amines 12, bearing an imidazole 3-oxide moiety (Scheme 7). The preparation of two types of imidazole derivatives bearing a hydrazide group was achieved by treatment of the corresponding esters with NH 2 NH 2 ·H 2 O in MeOH at room temperature. In the case of 4-(ethoxycarbonyl)imidazole 3-oxides 3, hydrazides of type 1 were formed with retention of the N-oxide structure (Scheme 1). Interestingly, due to a strong hydrogen bonding, no deoxygenation of the N→O function could be achieved even by treatment of 3 with Raney-nickel. The second type, 2-[(imidazol-2-yl)sulfanyl]acetohydrazides 2, was obtained from 1H-imidazole-2(3H)-thiones 4 in two steps via S-alkylation with methyl bromoacetate followed by treatment with NH 2 NH 2 ·H 2 O (Scheme 2). An imidazole 7, containing both types of hydrazide groups, was prepared analogously from ethyl 2,3-dihydro-2-thioxoimidazole-4-carboxylate 4d (Scheme 4). Both types of hydrazides, 1 and 2, were transformed successfully into the corresponding acylhydrazones 8 and 9, respectively (Scheme 5). Furthermore, it has been shown that hydrazides of type 1 are useful starting materials for the synthesis of 1,2,4-triazole-3-thiones 11 and 1,3,4-thiadiazole-2-amines 12, bearing an imidazole 3-oxide residue (Scheme 7).

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“…of K 2 CO 3, 5 mol% PdA C H T U N G T R E N N U N G (OAc) 2 and 6 mol% PA C H T U N G T R E N N U N G (t-Bu) 3 ·HBF 4 (Scheme 140). [180] The starting azine N-oxides were preferentially prepared using the methyltrioxorhenium (MTO)/H 2 O 2 oxidation system originally described by Sharpless, [181] but were also synthesized efficiently using in situ generated dimethyldioxirane as an oxidant. [182] On the other hand, azine N-oxides 262 were efficiently converted to the corresponding azines by N-oxide deoxygenation through treatment with Pd/C and ammonium formate in methanol at room temperature (Scheme 141).…”

Section: P(o)h Was Employed As the Prea C H T U N G T R E N N U N G Lmentioning

confidence: 99%

Cross‐Coupling of Heteroarenes by CH Functionalization: Recent Progress towards Direct Arylation and Heteroarylation Reactions Involving Heteroarenes Containing One Heteroatom

et al. 2014

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In recent years, transition metal-catalyzed direct (hetero)arylation reactions of heteroarenes with (hetero)aryl halides and pseudohalides have received significant attention as eco-friendly and economic alternatives to classical methods for the construction of heteroaryl-(hetero)aryl C À C bonds by transition metal-catalyzed cross-couplings involving the use of stoichiometric amounts of organometallic reagents. This critical review with 430 references covers the results obtained in the period January 2009 to February 2013 in the area of the transition metal-catalyzed direct inter-and intramolecular (hetero)arylation reactions of heteroarenes containing one heteroatom. Particular attention has been given to illustrate chemo-and site selectivity aspects of these reactions as well applications of these C À C bond forming reactions in the synthesis of pharmaceutically relevant compounds, natural products and their analogues and precursors. The most recent advancements into the mechanism(s) of these reactions have also been briefly reported.

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Palladium-Catalyzed Direct Arylation of Azine and Azole N-Oxides: Reaction Development, Scope and Applications in Synthesis

Cited by 401 publications

References 88 publications

Temperature-dependent polymorphism of N-(4-fluorophenyl)-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide: experimental and theoretical studies on intermolecular interactions in the crystal state

Temperature-dependent polymorphism of N-(4-fluorophenyl)-1,5-dimethyl-1H-imidazole-4-carboxamide 3-oxide: experimental and theoretical studies on intermolecular interactions in the crystal state

Synthesis and Selected Reactions of Hydrazides Containing an Imidazole Moiety

Cross‐Coupling of Heteroarenes by CH Functionalization: Recent Progress towards Direct Arylation and Heteroarylation Reactions Involving Heteroarenes Containing One Heteroatom

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