Regioselective Reaction of Heterocyclic<i>N</i>-Oxides, an Acyl Chloride, and Cyclic Thioethers

Frei, Przemysslaw; Jones, D. Heulyn; Kay, Steven T.; McLellan, Jayde; Johnston, Blair F.; Kennedy, Alan R.; Tomkinson, Nicholas C. O.

doi:10.1021/acs.joc.7b02457

Cited by 20 publications

(15 citation statements)

References 36 publications

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“…Tomkinson's team described a regioselective, three‐component coupling reaction between pyridine N ‐oxide, acyl chloride, and thioether in the presence of triethylamine to give 2‐thiolated pyridine 298 a and 298 b via carbene 300 (Scheme 89). [117] The reaction follows path A to give 298 a for less strained sulfide, whereas more strained sulfide expedites the elimination of 4‐nitrobenzoate, followed by recombination through ring opening to give 298 b .…”

Section: Simple C2‐h‐functionalizationmentioning

confidence: 99%

Recent Advances in the Synthesis of C2‐Functionalized Pyridines and Quinolines Using N‐Oxide Chemistry

et al. 2020

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While remarkable progress has recently been made for the direct C−H‐functionalization of azines, its application is still limited by a lack of accessible functional groups (primarily carbon‐based) and poor regioselectivity. In contrast, C2‐functionalized pyridines and quinolines can be easily synthesized by treating readily available N‐oxides with various reagents under appropriate activation conditions. This review seeks to comprehensively document the available synthetic methods for introducing functional groups at the C2 position of pyridines and quinolines. In this work, we highlight recent developments in the C2‐functionalization of pyridine and quinoline N‐oxides and address both the mechanisms and regioselectivity of the reactions. We also describe the pathways and reactive species involved in these processes and highlight a number of medically relevant nitrogen heteroaromatics.

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Section: Simple C2‐h‐functionalizationmentioning

confidence: 99%

Recent Advances in the Synthesis of C2‐Functionalized Pyridines and Quinolines Using N‐Oxide Chemistry

et al. 2020

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“…However, four‐membered thioethers resulted into a mixture of product ( 212 , 213 ) (Scheme 70). [181] …”

Section: Sulfenylationmentioning

confidence: 99%

“…[171] The scope of metal-free, base catalysed CÀ S/CÀ Se bond formation was not only resctricted to carbonates, but was also applicable to some alkali bases. Firouzabadi and co-workers [172] have reported NaOH mediated synthesis of dialkyl sulfide (184) using alkyl halide (182) and dithioxamide (181) as an efficient sulfenylating agent. The methodology was also extended to CÀ S bond formation using thia-Micheal addition by employing dithiooxamide as sulfur surrogate and benzyl halides as different Micheal acceptors (Scheme 62).…”

Section: Base Mediated Sulfenylationmentioning

confidence: 99%

Transition Metal‐Free Sulfenylation of C−H Bonds for C−S Bond Formation in Recent Years: Mechanistic Approach and Promising Future

et al. 2021

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Transition metal‐free sulfenylation of C−H bonds for C−S bond formation has recently emerged as sustainable protocols for the functionalisation of various molecules. Researchers have extensively developed such protocols for the construction of biologically relevant sulfur scaffolds. There has been a gradual shift from metal‐catalyzed to metal‐free C−S bond formation methodologies, because the latter offer environmentally benign and inherently safe access to novel synthetic routes in organic chemistry. The present review offers a dynamic discussion on recent advances in transition metal‐free C−S bond formation via C−H bond functionalization using different surrogate sulfenylating reagents. The review has comprehensively been devoted to radical and ionic mechanistic approaches. Some simple and eco‐friendly reagents for sulfenylation viz. tertbutyl hydrogen peroxide (TBHP), hydrogen peroxide (H2O2), iodine/potassium persulphate (I2/K2S2O8), inorganic bases, strong organic acids, iodine, I2/triphenyl phosphine (PPh3), N‐chlorosuccinamide (NCS), N‐bromosuccinamide (NBS), potassium iodate (KIO3), I2/bovine serum albumin (BSA), tetrabutyl ammonium iodide (TBAI)/HBr and graphene oxide along with their mechanistic approach has been detailed in this review. Moreover, modern methods for the C−S bond formation i. e., biocatalyst, electrochemical and visible light induced sulfenylation, and traditional sulfenylation methodologies have also been incorporated.

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“…Under similar conditions, the process can be carried out with cyclic sulfides. [ 22 ] In this case, the final product is a C2‐substituted heterocycle with a chlorine atom instead of an aroyl residue at the end of the side chain (Scheme 10). This provides additional possibilities for further functionalization by nucleophilic substitution.…”

Section: Deoxygenative C–h Functionalizationmentioning

confidence: 99%

Recent Progress in Non‐Catalytic C–H Functionalization of Heterocyclic N‐Oxides

2020

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Regioselective Reaction of HeterocyclicN-Oxides, an Acyl Chloride, and Cyclic Thioethers

Cited by 20 publications

References 36 publications

Recent Advances in the Synthesis of C2‐Functionalized Pyridines and Quinolines Using N‐Oxide Chemistry

Recent Advances in the Synthesis of C2‐Functionalized Pyridines and Quinolines Using N‐Oxide Chemistry

Transition Metal‐Free Sulfenylation of C−H Bonds for C−S Bond Formation in Recent Years: Mechanistic Approach and Promising Future

Recent Progress in Non‐Catalytic C–H Functionalization of Heterocyclic N‐Oxides

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