Chemie der Triphenyl‐(oder Tri‐<i>n</i>‐butyl‐)pyridylphosphoniumsalze, 1 Neue Methode zur regioselektiven Einführung von Phosphoniumgruppen in N‐heteroaromatische Ringsysteme

Anders, Ernst; Markus, Fritz

doi:10.1002/cber.19891220118

Cited by 39 publications

(12 citation statements)

References 14 publications

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“…It is noteworthy that nucleophilic reactions at the C atoms in the pyridinium moiety cannot be performed with “normal” N -substituted pyridinium salts. Activation of the C4 position needs, in general, very strong electron-withdrawing N -substituents, e.g., the CF 3 SO 2 group. , The trichlorovinyl group fulfills this condition and allows further related reactions, e.g., with Grignard reagents and trialkyl phosphites to give the N -(trichlorovinyl)-4-phenylmethyl- or 4-phoshonato-1,4-dihydropyridines ( 13 ) (74% yield) and ( 15 ) (80%), respectively. Compound 13 is very sensitive toward oxygen and should be handled under N 2 .…”

Section: Resultsmentioning

confidence: 99%

Preparation and Conversion of N-Halomethylpyridinium Halides. Comparison with Related Compounds

et al. 1999

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N-Halomethylpyridinium halides 1a-f (X-CH(2)Py(+)X(-), X = Cl, Br) have been synthesized from a three-component reaction mixture containing a thionyl halide 5, formaldehyde (6), and a pyridine 7. The salts 1a-f react readily with a variety of heterocyclic nucleophiles to yield (in general, nonsymmetrical) 1,1-bis(heteroarylium)methyl salts 2ea-hb, (pathway a). The use of trichloroacetaldehyde (9) instead of formaldehyde in this three-component reaction leads to a salt 10 in which one of the CH(2)-hydrogens was replaced by the electron-withdrawing CCl(3) substituent. This changes the standard reaction pathway a of 1 in solution toward nucleophiles completely: the chlorinated N-vinylpyridinium salts 11 and 12 were formed after the reaction of 10 with pyridine or triphenylphosphane. These are useful intermediates for the synthesis of new N- and 4-substituted 1,4-dihydropyridines 13-15 as could be demonstrated for compound 11. To explain the reactivity pattern of compounds 1 and 10 and the related structures (MeO-CH(2)Py(+), 16, and Me(3)SiO-CH(2)Py(+), 17) we calculated, using ab initio and DFT methods, reaction pathways a and b, both in the gas phase and in solution using ammonia as a model nucleophile. For all of these compounds, pyridine displacement (pathway b) dominates in the gas phase. As an example the energy gap between these two transition states for 1a turns out to be relatively small (11.6 kcal/mol in favor of pathway b, TS2). Solvation effects can therefore stabilize the corresponding transition state TS1 more effectively. In a MeCN solution, TS1 is 1.6 kcal/mol less energetic than TS2.

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Section: Resultsmentioning

confidence: 99%

Preparation and Conversion of N-Halomethylpyridinium Halides. Comparison with Related Compounds

et al. 1999

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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.…”

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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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“…Preliminary investigations show that this method can be extended to the heteroarylphosphonium salts 33. 4 The 4phenylheteroaryls 34a,b were obtained in acceptable yields from the phosphonium salts 33a,b (Table 4). After 30 min, the resulting solution was warmed to 0°C.…”

Section: Methodsmentioning

confidence: 99%

“…This procedure profits from the quantitative in situ formation of N-(trifluoromethylsulfonyl)pyridinium triflate, which reacts with P(OR) 3 . 4 The addition of Et 3 N to the reaction mixture transforms the intermediate N-trifluoromethanesulfonyldihydropyridines in to the corresponding 4-phosphonato substituted pyridines. The easy removal of the N-triflyl group then allows the straightforward repetition of this procedure, which finally yields 2,4-bis(dialkoxyphosphoryl)pyridines.…”

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N-Heteroarylphosphonates, Part II. Synthesis and Reactions of 2- and 4-Phosphonatoquinolines and Related Compounds

Haase¹,

Günther²,

Görls³

et al. 1999

Synthesis

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We extend our synthetic method for the efficient preparation of dialkoxyphosphoryl-and phosphonio-disubstituted pyridines to include the preparation of other phosphonato substituted N-heterocycles. The key to the success of this method lies in the employment of cationic N-(trifluoromethylsulfonyl)heteroarylium triflates that are activated towards nucleophilic attack. The P(O)(OR) 2 group can be transformed into the P(S)(OR) 2 functionality. We report first attempts to substitute the P(O)(OR) 2 moiety with C-nucleophiles. In addition to our synthetic results, the X-ray structures of two (dimethoxyphosphoryl)trifluoromethanesulfonyldihydro-Nheteroarenes are discussed. We also give complete carbon ( 13 C) and phosphorus ( 31 P)-NMR spectra of a series of 2-and 4-phosphonic ester substituted heteroaryl compounds and their dihydro analogs.Heterocyclic compounds containing P(O)(OR) 2 functionalities in which the phosphorus group is ortho or para to the nitrogen in the heterocycle deserve interest as they have been used to inhibit the corrosion of ferrous metals and can be employed as passive coating agents by dissolving them in the corrosive medium. Examples are brines, weak inorganic acids, CO 2 , H 2 S, etc. These compounds and their derivatives are also employed as additives for sludging and cutting oils, as wetting, rewetting, dispersing and as antistatic agents in the textile and polymer industry. Further useful applications are as emulsifiers for insecticides and agricultural chemical mixtures. 1 In contrast to the corresponding non-quaternized compounds, which show no microbiocidal activity, the quaternized compounds are active as biocides or biostats. These compounds are employed in many areas of industrial chemistry such as bactericides, herbicides, chelating agents, etc. 2 We reported in a recent article 3 that the conclusions drawn from our new synthetic procedure for the preparation of dialkoxyphosphoryl substituted pyridines via N-(trifluoromethylsulfonyl)pyridinium triflates and the appropriate dihydropyridines lead away from the exclusive use of pyridine itself. This procedure profits from the quantitative in situ formation of N-(trifluoromethylsulfonyl)pyridinium triflate, which reacts with P(OR) 3 . 4 The addition of Et 3 N to the reaction mixture transforms the intermediate N-trifluoromethanesulfonyldihydropyridines in to the corresponding 4-phosphonato substituted pyridines. The easy removal of the N-triflyl group then allows the straightforward repetition of this procedure, which finally yields 2,4-bis(dialkoxyphosphoryl)pyridines.In the present article, we report on investigations which tested the influence of steric hindrance (Scheme 1) on the success of our method by employing 3,5-diphenylpyridine (1) and 2,6-diphenylpyridine (5). The di-meta substituted compound 1 reacted as expected to form compound 3, which could be rearomatized to 4 by deprotonation with BuLi. However, the di-ortho substituted compound 5 did not react with Tf-O-Tf 2. Since the electronic properties of the nitrogen atom can...

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Chemie der Triphenyl‐(oder Tri‐n‐butyl‐)pyridylphosphoniumsalze, 1 Neue Methode zur regioselektiven Einführung von Phosphoniumgruppen in N‐heteroaromatische Ringsysteme

Cited by 39 publications

References 14 publications

Preparation and Conversion of N-Halomethylpyridinium Halides. Comparison with Related Compounds

Preparation and Conversion of N-Halomethylpyridinium Halides. Comparison with Related Compounds

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

N-Heteroarylphosphonates, Part II. Synthesis and Reactions of 2- and 4-Phosphonatoquinolines and Related Compounds

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