Transition Metal‐Free sp<sup>3</sup> C–H Functionalization of Arylacetic Acids for the Synthesis of 1,3,5‐Triazines

Pardeshi, Sachin D.; Sathe, Pratima A.; Pawar, Balu V.; Vadagaonkar, Kamlesh S.; Chaskar, Atul

doi:10.1002/ejoc.201800178

Cited by 12 publications

(4 citation statements)

References 40 publications

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“…Generally, aldehyde surrogates include aryl methanols 187 (Scheme 56a), 210 tertial amines 188 (Scheme 56b), 211 methylarenes 189 (Scheme 56c), 212 styrenes 190 (Scheme 56d), 213 aryl methylamines 191 (Scheme 56e), 214 aryl methyl ketones 192 (Scheme 56f), 215 isatins 193 (Scheme 56g), 216 and aryl acetic acids 194 (Scheme 56h). 217 Under similar reaction conditions, these surrogates were initially transformed into aldehydes or imines, which then reacted with two amidine molecules. In these annulation reactions, a variety of 2,4,6-trisubstituted 1,3,5triazines with broad functionality were constructed in moderate to excellent yields.…”

Section: [2 + 2 + 2] Annulationmentioning

confidence: 99%

“…Inspired by this seminal work, a bunch of aldehyde surrogates have been used for the synthesis of 2,4,6-trisubstituted 1,3,5-triazines over the past few years (Scheme ). Generally, aldehyde surrogates include aryl methanols 187 (Scheme a), tertial amines 188 (Scheme b), methylarenes 189 (Scheme c), styrenes 190 (Scheme d), aryl methylamines 191 (Scheme e), aryl methyl ketones 192 (Scheme f), isatins 193 (Scheme g), and aryl acetic acids 194 (Scheme h) . Under similar reaction conditions, these surrogates were initially transformed into aldehydes or imines, which then reacted with two amidine molecules.…”

Section: 35-triazinesmentioning

confidence: 99%

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Triazines: Syntheses and Inverse Electron-demand Diels–Alder Reactions

et al. 2021

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Triazines are an important class of six-membered aromatic heterocycles possessing three nitrogen atoms, resulting in three types of regio-isomers: 1,2,4-triazines (a-triazines), 1,2,3-triazines (v-triazines), and 1,3,5-triazines (s-triazines). Notably, the application of triazines as cyclic aza-dienes in inverse electron-demand Diels–Alder (IEDDA) cycloaddition reactions has been established as a unique and powerful method in N-heterocycle synthesis, natural product preparation, and bioorthogonal chemistry. In this review, we comprehensively summarize the advances in the construction of these triazines via annulation and ring-expansion reactions, especially emphasizing recent developments and challenges. The synthetic transformations of triazines are focused on IEDDA cycloaddition reactions, which have allowed access to a wide scope of heterocycles, including pyridines, carbolines, azepines, pyridazines, pyrazines, and pyrimidines. The utilization of triazine IEDDA reactions as key steps in natural product synthesis is also discussed. More importantly, a particular attention is paid on the bioorthogonal application of triazines in fast click ligation with various strained alkenes and alkynes, which opens a new opportunity for studying biomolecules in chemical biology.

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Section: [2 + 2 + 2] Annulationmentioning

confidence: 99%

Section: 35-triazinesmentioning

confidence: 99%

Triazines: Syntheses and Inverse Electron-demand Diels–Alder Reactions

et al. 2021

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“…15‐1). During the tandem cyclization, the Schiff's base intermediate 15.2 were attacked by pyrroles, amines,– amides, phenols, and thiophenols . For example, Chaskar and co‐workers reported the study on copper‐catalyzed synthesis of pyrrolo[1,2‐ a ]quinoxalines 15.3 in the presence of O 2 as an oxidant (Eq.…”

Section: Decarboxylationmentioning

confidence: 99%

Arylacetic Acids in Organic Synthesis

et al. 2019

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Arylacetic acids are widely used in organic reactions and their recent advances are summarized in six categories according to their triggered pathways: (1) the acid as directing group in ortho-or meta-CÀ H activation; (2) decarboxylation; (3) deprotonation; (4) nucleophilic methylenes; (5) nucleophilic acids; (6) electrophilic acids. Reactions with alkenes, alkynes, aldehydes, amines, water, Grignard reagents, silanes and so forth are discussed. We hope this Minireview will promote future research in this area. Recently, the Zeng group [3g] reported a weakly coordinationassisted alkynylation of arylacetic acids with iridium catalysis under air atmosphere (Eq. 2-2). It was supported the sixmembered ring cycloiridiated 2.5 acted as the key intermediate. The alkynylation of indole, thiophene, pyrrole, and benzo[b] thiophene afforded better yields than phenylacetic acids. The acid moiety could also participated in the intramolecular ortho-CÀ H activation, which was developed by the Shi group to obtain lactonization 2.6 (Eq. 2-3) (Scheme 2). Meta-CÀ H ArylationThe study of Yu group [3e] in 2017 revealed a successful control of meta selectivity 3.1 of arylation from aryl iodides (Eq. 3-1). The use of mono-protected 3-amino-2-hydroxypyridine (as ligand) and 2-carbomethoxynorbornene (NBE-CO 2 Me) were crucial. In the absence of NBE-CO 2 Me, only ortho-arylated product was obtained. This method was still efficient in a gramsale (Scheme 3). Decarboxylation Decarboxylative CouplingAs shown in Scheme 4, the decarboxylation could generate benzyl radicals 4.1. Then, direct couplings of 4.1 with diverse [ + ] These authors contributed equally. Scheme 1. Six categories based on triggered mechanism. 2 3 4 5 6 7 8 . Passerini Three-Component ReactionThe Passerini reaction was the oldest multicomponent reaction (MCR) [37d] in which isocyanides, carboxylic acids and aldehydes were used. It was powerful for the rapid construction of complex molecules. The tactic to expand the scope of Passerini reaction was to use surrogates of the carbonyl partners. As described in Scheme 51, syn-chlorooximes, [37b] diazoketones, [37c] alcohols, [37d,e] azirines [37f] and isatins [37g] could be employed instead of aryl or alkyl aldehydes [37a] (Scheme 51). Besides, in 2018, Zhang and co-workers [37] have firstly reported asymmetric phosphoric acid-catalyzed four-component Ugi reaction, which Scheme 45. BTM-catalyzed cycloaddition. Scheme 46. HBTM-catalyzed cycloaddition. Scheme 47. TFA-catalyzed reaction. Scheme 48. Friedel-Crafts triggered tandem reactions. Scheme 49. C-acylation of 1,3-diones. Scheme 50. C-acylation of 1,3-indandiones.

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“…Similarly, polythene glycol mediated aerobic oxidative tandem cyclization of benzylamines with amidines[19a] and oxidative C(sp 3 )–H amination of tertiary amines with amidines using Cu II[19b] or iodine[19c] as catalysts were also further established as novel strategies for the synthesis of polysubstituted 1,3,5‐triazine. As an alternative, other carbon synthons, such as aryl acetic acids, styrenes, isatins and alkyl ethers were also developed as C1 coupling precursors introduced to this strategy …”

Section: Introductionmentioning

confidence: 99%

I₂/K₂S₂O₈ Mediated Direct Oxidative Annulation of Alkylazaarenes with Amidines for the Synthesis of Substituted 1,3,5‐Triazines

2020

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A direct method for the synthesis of heteroaryl‐substituted 1,3,5‐triazines from readily available methyl‐azaarenes and amidines has been developed. The present method involves iodine mediated cascade aerobic C(sp3)–H oxidative amination and following condensation, cyclization with amidine. Both of methyl quinoline, pyridine and benzothiazole derivatives could be well tolerated to react with various amidines leading to corresponding products in good to excellent yields.

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Transition Metal‐Free sp³ C–H Functionalization of Arylacetic Acids for the Synthesis of 1,3,5‐Triazines

Cited by 12 publications

References 40 publications

Triazines: Syntheses and Inverse Electron-demand Diels–Alder Reactions

Triazines: Syntheses and Inverse Electron-demand Diels–Alder Reactions

Arylacetic Acids in Organic Synthesis

I₂/K₂S₂O₈ Mediated Direct Oxidative Annulation of Alkylazaarenes with Amidines for the Synthesis of Substituted 1,3,5‐Triazines

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Transition Metal‐Free sp3 C–H Functionalization of Arylacetic Acids for the Synthesis of 1,3,5‐Triazines

Cited by 12 publications

References 40 publications

Triazines: Syntheses and Inverse Electron-demand Diels–Alder Reactions

Triazines: Syntheses and Inverse Electron-demand Diels–Alder Reactions

Arylacetic Acids in Organic Synthesis

I2/K2S2O8 Mediated Direct Oxidative Annulation of Alkylazaarenes with Amidines for the Synthesis of Substituted 1,3,5‐Triazines

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Transition Metal‐Free sp³ C–H Functionalization of Arylacetic Acids for the Synthesis of 1,3,5‐Triazines

I₂/K₂S₂O₈ Mediated Direct Oxidative Annulation of Alkylazaarenes with Amidines for the Synthesis of Substituted 1,3,5‐Triazines