Six-Membered Ring Systems: Pyridine and Benzo Derivatives

Kishbaugh, Tara L. S.

doi:10.1016/b978-0-08-096807-0.00012-9

Cited by 21 publications

(15 citation statements)

References 173 publications

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“…The effect of several alternative solvents on the D:E product ratio was examined, but none performed as well as dichloromethane (cf. entries 9,[13][14][15][16][17]. Nevertheless, moderate to good yields of product can be obtained in both halogenated and nonpolar solvents.…”

Section: Resultsmentioning

confidence: 99%

“…8 N-Alkyl, 9 N-acyl, 10 N-fluoro, 11 N-oxide, 12 and other N-activated pyridinium salts 13 promote a broad range of valuable transformations or act as building blocks for cycloadditions, rearrangements, reductions, oxidations, transition metal couplings, and nucleophilic additions. 14 Protonated pyridinium salts such as pyridinium p-toluenesulfonate (PPTS), 15 a mild organic soluble acid, and pyridinium chlorochromate (PCC), 16 a mild organic soluble oxidant, represent two mainstay reagents in organic synthesis. In addition to synthetic applications, pyridinium salts have been exploited for their physicochemical properties as surfactants, phase transfer agents, optoelectronics, and dyes, and for their biological activities as antimicrobial agents.…”

mentioning

confidence: 99%

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Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

Blades¹,

McConnell²,

Rodrigues³

et al. 2019

Preprint

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<div>N-Quaternized ketene N,O-acetals are typically an unstable, transient class of compounds most commonly observed as reactive intermediates. In this report, we describe a general approach to a variety of benchstable N-quaternized ketene N,O-acetals via treatment of pyridine or aniline bases with ethoxyacetylene and an appropriate Brønsted or Lewis acid (triflic acid, triflimide, or scandium(III) triflate). The resulting pyridinium and anilinium salts may be used as reagents or synthetic intermediates in multiple reaction types. For example, N-(1-ethoxyvinyl) pyridinium or anilinium salts can thermally release highly reactive O-ethyl ketenium ions that undergo electrophilic aromatic substitution with electron rich arenes. N-(1-ethoxyvinyl)-2-halopyridinium salts can also be utilized in peptide couplings as a derivative of Mukaiyama reagents, or react with alcohol and amines in nucleophilic aromatic substitutions.</div>

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

Blades¹,

McConnell²,

Rodrigues³

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

Section: Table 1 -Evaluation Of Reaction Parameters For the Synthesis Of N-(1-ethoxyvinyl) 2-chloropyridinium Salts Dmentioning

confidence: 99%

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

McConnell¹,

Blades²,

Rodrigues³

et al. 2021

Preprint

View full text Add to dashboard Cite

N-Quaternized ketene N,O-acetals are typically an unstable, transient class of compounds most commonly observed as reactive intermediates. In this report, we describe a general synthetic approach to a variety of bench-stable N-quaternized ketene N,O-acetals via treatment of pyridine or aniline bases with acetylenic ethers and an appropriate Brønsted or Lewis acid (triflic acid, triflimide, or scandium(III) triflate). The resulting pyridinium and anilinium salts can be used as reagents or synthetic intermediates in multiple reaction types. For example, N-(1-ethoxyvinyl)pyridinium or anilinium salts can thermally release highly reactive O-ethyl ketenium ions for use in acid catalyst-free electrophilic aromatic substitutions. N-(1-Ethoxyvinyl)-2-halopyridinium salts can be employed in peptide couplings as a derivative of Mukaiyama reagents or react with amines in nucleophilic aromatic substitutions under mild conditions. These preliminary reactions illustrate the broad potential of these currently understudied compounds in organic synthesis.

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“…For example, Dudley’s reagent is a bench-stable pyridinium salt for O - and N -benzylation under neutral conditions N -acyl, N -fluoro, N -oxo, N- amino, and other N -activated pyridinium salts promote a broad range of valuable transformations or act as building blocks for cycloadditions, rearrangements, reductions, oxidations, transition-metal couplings, and nucleophilic additions . Protonated pyridinium salts such as pyridinium p -toluenesulfonate (PPTS), a mild organic soluble acid, and pyridinium chlorochromate (PCC), a mild organic soluble oxidant, represent two mainstay reagents in organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…8 N-Alkyl, 9 N-acyl, 10 N-fluoro, 11 N-oxo, 12 N-amino, 13 and other Nactivated pyridinium salts 14 promote a broad range of valuable transformations or act as building blocks for cycloadditions, rearrangements, reductions, oxidations, transition-metal cou-plings, and nucleophilic additions. 15 Protonated pyridinium salts such as pyridinium p-toluenesulfonate (PPTS), 16 a mild organic soluble acid, and pyridinium chlorochromate (PCC), 17 a mild organic soluble oxidant, represent two mainstay reagents in organic synthesis. In addition to synthetic applications, pyridinium salts have been exploited for their physicochemical properties as surfactants, phase transfer agents, optoelectronics, and dyes, and for their biological activities as antimicrobial agents.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

et al. 2021

View full text Add to dashboard Cite

N-Quaternized ketene N,O-acetals are typically an unstable, transient class of compounds most commonly observed as reactive intermediates. In this report, we describe a general synthetic approach to a variety of bench-stable N-quaternized ketene N,O-acetals via treatment of pyridine or aniline bases with acetylenic ethers and an appropriate Brønsted or Lewis acid (triflic acid, triflimide, or scandium(III) triflate). The resulting pyridinium and anilinium salts can be used as reagents or synthetic intermediates in multiple reaction types. For example, N-(1ethoxyvinyl)pyridinium or anilinium salts can thermally release highly reactive O-ethyl ketenium ions for use in acid catalyst-free electrophilic aromatic substitutions. N-(1-Ethoxyvinyl)-2-halopyridinium salts can be employed in peptide couplings as a derivative of Mukaiyama reagents or react with amines in nucleophilic aromatic substitutions under mild conditions. These preliminary reactions illustrate the broad potential of these currently understudied compounds in organic synthesis.

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Six-Membered Ring Systems: Pyridine and Benzo Derivatives

Cited by 21 publications

References 173 publications

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

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