Recyclization of polysubstituted pyridinium salts

Shkil, G. P.; Lusis, V. K.; Muceniece, D.; Sagitullin, R. S.

doi:10.1016/0040-4020(95)00474-m

Cited by 17 publications

(5 citation statements)

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“…The Kost-Sagitullin rearrangement was first discovered and studied under the leadership of Prof. A. N. Kost in derivatives of pyridine and pyrimidine [5,[64][65][66][67][68][69][70][71][72][73][74][75][76][77]. Such recyclizations were realized both in N-alkylazinium salts and in annelated azine systems containing a bridging nitrogen atom (common to the two heterocycles).…”

Section: Isomerization N-c Recyclization (The Kost-sagitullin Rearranmentioning

confidence: 99%

Kost-Sagitullin Rearrangement and Other Isomerization Recyclizations of Pyrimidines. (Review)

Danagulyan

2005

Chem Heterocycl Compd

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Section: Isomerization N-c Recyclization (The Kost-sagitullin Rearranmentioning

confidence: 99%

Kost-Sagitullin Rearrangement and Other Isomerization Recyclizations of Pyrimidines. (Review)

Danagulyan

2005

Chem Heterocycl Compd

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“…Recyclization of the salt 1b occurs regiospecifically; the possible product of heterocyclization with participation of the cyano group [2,3] is not observed. The meta-terphenyls with substituents on one ring that we synthesized cannot be obtained by other known methods.…”

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confidence: 98%

Novel Approach to Synthesis of meta-Terphenyls

Сагитуллина

Glizdinskaya

Sagitullin

2005

Chem Heterocycl Compd

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In studying the synthetic possibilities for isomerization recyclization of nitropyridinium salts we described earlier in [1], we have established that the reaction can be used to synthesize meta-terphenyls (meta-diphenylbenzenes).Rearrangement of pyridinium salts 1a-d when treated with an aqueous alcoholic base occurs at room temperature, and leads to diphenylbenzenes 2a-d in 41-70% yield. Compounds 2a-d are formed through the open form A, which is formed after attack by the hydroxyl anion on the position ortho to the nitro group. The benzene ring is formed by an intramolecular aldol-crotonic condensation of the benzoyl group (formed after opening of the pyridine ring) at the methyl group of the open form A. A byproduct of recyclization of salt 1a is the pyridone 3a (9% yield), which is formed from the open form B by intramolecular acylation of the ester group of the enamine moiety. Recyclization of the salt 1b occurs regiospecifically; the possible product of heterocyclization with participation of the cyano group [2, 3] is not observed. N X Me Me Ph Ph O 2 N OH N Me Me X Ph Ph O 2 N Me X Ph Ph O 2 N NH O Me X Ph Ph O 2 N NHMe Me O N O 2 N Ph COMe Ph + X = COOEt B A 2a-d 1a-d 3a 1-3 a X = COOEt, b X = CN, c X = COMe, d X = CONHPh + + __________________________________________________________________________________________

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“…Nicotinonitriles 1a-c were prepared by a rearrangement of 3,5-dicyanopyridinium salts upon treatment with sodium hydroxide. 19,20 The construction of a pyrazole ring in a fused ring system was done upon N-nitrosation of a secondary amino group in compounds 1a-c with sodium nitrite in acetic acid followed by the reduction of resulting N-nitrosoamines 2a-c † with zinc powder in acetic acid. During the reduction of the N-nitroso group of 2a-c to a substituted hydrazino group, intramolecular condensation onto acetyl group of pyridine ring simultaneously occurred and resulted in pyrazole ring closure to form 3a-c. ‡ All the reactions were performed under mild conditions and produced 2a-c and 3a-c in high yields.…”

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confidence: 99%