Chemie der Triphenyl‐(oder Tri‐<i>n</i>‐butyl‐)pyridylphosphoniumsalze, 2. 2,4‐Pyridindiylbis(phosphoniumsalze)

Anders, Ernst; Markus, Fritz

doi:10.1002/cber.19891220119

Cited by 25 publications

(10 citation statements)

References 11 publications

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“…Triflate-activated pyridinium salts offer greater synthetic flexibility and consequently have garnered much interest. The first accounts described the addition of phosphines to the activated pyridine, , with pyridyl phosphanes being an important class of soft transition metal ligands . Complete formation of the pyridinium triflate occurred before attack of the phosphine.…”

Section: Nucleophilic Additions To N-heteroatom Pyridinium Speciesmentioning

confidence: 99%

“…A clear advantage of the method was the fact that no directing group was required in the synthesis, which is unprecedented in the preparation of these compounds. The dihydropyridine intermediate is not stable, and the product decomposes to give the 4-substituted pyridine . Double addition to form potential 4,4′-products was avoided by the use of a large excess of pyridine, protecting the product from further activation …”

Section: Nucleophilic Additions To N-heteroatom Pyridinium Speciesmentioning

confidence: 99%

“…The dihydropyridine intermediate is not stable, and the product decomposes to give the 4-substituted pyridine . Double addition to form potential 4,4′-products was avoided by the use of a large excess of pyridine, protecting the product from further activation …”

Section: Nucleophilic Additions To N-heteroatom Pyridinium Speciesmentioning

confidence: 99%

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Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

et al. 2012

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Introduction 2643 2. Nucleophilic Addition of Organometallic Reagents to N-Acyl Pyridinium Salts 2644 2.1. Regioselective Additions to N-Acyl Pyridinium Species and Their Derivatives 2644 2.1.1. Influence of Pyridine Ring Substituents on Regioselectivity of Addition 2646 2.1.2. Control of Regio-and Diastereoselectivity by the Introduction of Removable Blocking Groups 2648 2.2. Synthesis of 4-Pyridones: 1,2-Addition to 4-Methoxypyridines 2649 2.2.1. Diastereoselective Addition to 3-Trialkylsilyl-4-methoxypyridines 2651 2.2.2. Application in the Synthesis of Natural Products Containing Chiral Piperidine Units 2652 2.3. Diastereoselective 1,2-Addition to N-Imidoyl Pyridinium Salts 2652 2.4. Enantioselective 1,2-Addition Controlled by a Chiral Catalyst 2657 2.5. Diastereoselective 1,4-Addition Controlled by Pyridine 3-Substituents 2657 3. Nucleophilic Addition to N-Alkyl Pyridinium Salts and Their Derivatives 2659 3.1. Regioselective Additions to N-Alkyl Pyridinium SaltsNature of the Nucleophile 2659 3.1.1. Organometallic Reagents as Nucleophiles 2659 3.1.2. Cyanide as Nucleophile 2663 3.2. Diastereoselective Additions of Organometallic Reagents to N-Alkyl Pyridinium Salts 2663 3.3. Regioselective Additions of Enolates to N-Alkyl Pyridinium Salts 2666 3.3.1. Wenkert Procedure: Seminal Work 2667 3.3.2. Wenkert Procedure: Addition of Nucleophiles Positioned at the Nitrogen of Indole Derivatives 2670 3.3.3. Wenkert Procedure: Addition of Enolates Located at the C-2/C-3 Position of Indoles 2671 3.3.4. Addition of Miscellaneous Nucleophiles to N-Alkyl Pyridinium Species 2674 4. Nucleophilic Additions to N-Heteroatom Pyridinium Species 2676 4.1. Nucleophilic Additions to Pyridine N-Oxides and N−O Salts 4.1.1. Properties, Synthesis, and Deprotection of Pyridine N-Oxides 4.1.2. Addition of Grignard Reagents to Pyridine N-Oxides 4.1.3. Addition of Cyanide Nucleophiles via Reissert-Type Reactions 4.1.4. Addition of Hetero Nucleophiles to Pyridine N-Oxides and N−O Salts 4.

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Section: Nucleophilic Additions To N-heteroatom Pyridinium Speciesmentioning

confidence: 99%

Section: Nucleophilic Additions To N-heteroatom Pyridinium Speciesmentioning

confidence: 99%

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Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

et al. 2012

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“…11 Amethod for the regiospecific introduction of the PR 3 group into the C4 position of the unsubstituted pyridine ring system was described by our group some years ago (Scheme 1). 12,13 This procedure takes advantage of the quantitative in situ formation of N-(trifluoromethylsulfonyl)pyridinium triflate (Ntriflylpyridinium triflate, 3), which reacted with phosphanes via dihydropyridines 4 and addition of NEt 3 to give the phosphonium salts 5. The isomeric C2-substituted products have not been observed.…”

mentioning

confidence: 99%

“…For synthetic applications, salts such as 5 and 6 deserve interest as they allow a variety of pathways to further classes of substituted heterocyclic compounds. 13 For reasons which are obvious from the introductory part, in the present paper we summarize our efforts which finally led to C2/C4-bis[PO(OR) 2 ]-and C2/C4-PO(OR) 2 / PR 3 + -disubstituted pyridines. The investigation presented here takes advantage of the observation that, obviously, the N-SO 2 CF 3 substituent plays an exceptional role (vide supra), which can be understood on the basis of ab initio and semiempirical MO calculations.…”

mentioning

confidence: 99%

Synthesis of PO(OR)2- and PR3+-Disubstituted Pyridines via N-(Trifluoromethylsulfonyl)pyridinium Triflates

Haase¹,

Goerls²,

Anders³

1998

Synthesis

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The efficient synthesis of dialkoxyphosphoryl-and phosphonio-substituted pyridines is reported. The cationic heterocycle of N-(trifluoromethylsulfonyl)pyridinium triflate (3), or of analogous N-(trifluoromethylsulfonyl) compounds prepared from pyridine-4phosphonium salts 5, turns out to be sufficiently activated to allow attack of P(OR) 3 and PR 3 + nucleophiles to give the novel compounds bis(dialkoxyphosphoryl)pyridines 11 and phosphonio(dialkoxyphosphoryl)pyridines 13. For example, 13a-d, with PO(OR) 2 at the C2 and PR 3 + at the C4 position, represent the first examples of an Nheteroaromatic ring substituted by both dialkoxyphosphoryl and phosphonio moieties. The structure of 13b [PPh 3 + /PO(O-i-Pr) 2 ] was confirmed by X-ray analysis. In most cases, the intermediate 1-(trifluoromethylsulfonyl)dihydropyridines, such as 7, 8 (monosubstituted) or 10a and b and 12a-d (disubstituted), are sufficiently stable for isolation.

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A Unified Approach to Couple Aromatic Heteronucleophiles to Azines and Pharmaceuticals

2018

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Coupling aromatic heteronucleophiles to arenes is ac ommon way to assemble drug-like molecules.M any methods operate via nucleophiles intercepting organometallic intermediates,v ia Pd-, Cu-, and Ni-catalysis,t hat facilitate carbon-heteroatom bond formation and avariety of protocols. We present an alternative,unified strategy where phosphonium salts can replicate the behavior of organometallic intermediates.U nder an arrows et of reaction conditions,avariety of aromatic heteronucleophile classes can be coupled to pyridines and diazines that are often problematic in metal-catalyzed couplings,s uch as where (pseudo)halide precursors are unavailable in complex structures with multiple polar functional groups.

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Chemie der Triphenyl‐(oder Tri‐n‐butyl‐)pyridylphosphoniumsalze, 2. 2,4‐Pyridindiylbis(phosphoniumsalze)

Cited by 25 publications

References 11 publications

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition toN-Activated Pyridines

Synthesis of PO(OR)2- and PR3+-Disubstituted Pyridines via N-(Trifluoromethylsulfonyl)pyridinium Triflates

A Unified Approach to Couple Aromatic Heteronucleophiles to Azines and Pharmaceuticals

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