Unexpected ring-opening of 2,3-dihydropyridines

Hoffelner, Michael-Hannes; Seebacher, Werner; Kaiser, Marcel; Mäser, Pascal; Pferschy‐Wenzig, Eva‐Maria; Saf, Robert; Belaj, Ferdinand; Kretschmer, Nadine; Alajlani, Muaaz; Brantner, Adelheid; Bauer, Rudolf; Weis, Robert

doi:10.1007/s00706-021-02850-3

Cited by 2 publications

(1 citation statement)

References 26 publications

(47 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zincke first observed this reactivity when combining a secondary amine with a dinitrophenylpyridinium salt. Other instances of azatrienes spontaneously formed from substituted DHP salts involve 1,2-DHPs substituted at C2 with other heteroatoms, aryl or alkyne R groups, , or amino groups that serve as π donors (vide supra) . Examples of metal-coordinated azatrienes are rare and almost always involve sigma coordination through a heteroatom.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of 1-Azatriene Complexes of Tungsten: Metal-Promoted Ring-Opening of Dihydropyridine

Dabbs,

Ericson,

Dickie

et al. 2024

Organometallics

View full text Add to dashboard Cite

For nearly a century, chemists have explored how transition-metal complexes can affect the physical and chemical properties of linear conjugated polyenes and heteropolyenes. While much has been written about higher hapticity complexes (η 4 −η 6 ), less is known about the chemistry of their η 2 analogues. Herein, we describe a general method for synthesizing 5,6-η 2 -(1azatriene) tungsten complexes via a 6π-azaelectrocyclic dihydropyridine ring-opening that is promoted by the π-basic nature of {WTp(NO)(PMe 3 )}. This study includes detailed spectroscopic and crystallographic data for the η 2 -dihydropyridine and η 2 -1azatriene complexes, both of which were prepared as single regio-and stereoisomers.

show abstract

Section: Resultsmentioning

confidence: 99%

Synthesis of 1-Azatriene Complexes of Tungsten: Metal-Promoted Ring-Opening of Dihydropyridine

Dabbs,

Ericson,

Dickie

et al. 2024

Organometallics

View full text Add to dashboard Cite

show abstract

Synthesis and properties of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide

Aizina,

Tkachuk,

Shaglaeva

2024

Izvestiâ vuzov. Prikladnaâ himiâ i biotehnologiâ

View full text Add to dashboard Cite

The present work continues a systematic study to find efficient and accessible methods for the synthesis ofN-sulfonylimines of polyhaloaldehydes and to analyze their properties. In the reaction of N,N-dichlorobenzene sulfon-amide with tribromoethylene, N-(2,2,2-tribromoethylidene)amide of 4-chlorobenzenesulfonic acid was obtained for the first time with a quantitative yield at boiling water bath temperature in carbon tetrachloride medium. The infrared spectra of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide reveal the absorption bands of sulfonic (1360 and 1165 cm-1) and NH (3275 cm-1) groups, while the 1H NMR spectra show a signal for azomethine protons within the region of 8.3–8.6 ppm. The 13C NMR spectra exhibit a signal for the CBr3 group within the region of ~31–43 ppm, while the signal characteristic of the CBr2Сl group within the region of ~53–56 ppm is absent. This means that no imine of dibromochloroacetic aldehyde is formed during the reaction. Thus, an efficient method for the synthesis of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide was developed, and the chemoselectivity of this reaction was found to depend on the process temperature. It was shown that N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide has amidoalkylating properties. A reaction of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide with benzene, toluene, anisole, and 2-chlorothiophene in the presence of an acid catalyst yielded p-substituted aromatic derivatives and 2,5-substituted thiophene derivatives. Infrared spectroscopy and NMR spectroscopy (1H, 13C) revealed that the substitution reaction proceeds regioselectively. All the obtained products were isolated in pure form as powders soluble in polar organic solvents and insoluble in water. The yields of 4-chloro-N-(1-phenyl-2,2,2-tribromoethyl)-benzenesulfonamide, 4-chloro-N-[1-(4-methylphenyl)-2,2,2-tribromoethyl]-benzenesulfonamide, 4-chloro-N-[1-(4-methoxyphenyl)-2,2,2-tribromoethyl]-benzene-sulfonamide, and 4-chloro-N-[2,2,2-tribromoethyl-1-(5-chloro-2-thienyl)ethyl]-benzenesulfonamide amounted to 74, 72, 64, and 74 %, respectively.

show abstract

Unexpected ring-opening of 2,3-dihydropyridines

Cited by 2 publications

References 26 publications

Synthesis of 1-Azatriene Complexes of Tungsten: Metal-Promoted Ring-Opening of Dihydropyridine

Synthesis of 1-Azatriene Complexes of Tungsten: Metal-Promoted Ring-Opening of Dihydropyridine

Synthesis and properties of N-(2,2,2-tribromoethylidene)-4-chlorobenzenesulfonamide

Contact Info

Product

Resources

About