10199-66-3Relevant academic research and scientific papers
1-Benzoylazoles: An experimental (NMR and crystallography) and theoretical study
Claramunt,Cornago,Sanz,Santa-María,Foces-Foces,Alkorta,Elguero
, p. 199 - 212 (2002)
Five N-benzoylazoles (imidazole, pyrazole, indole, benzimidazole and carbazole) have been prepared following modified literature procedures. Their NMR spectra in solution (1H, 13C and 15N) have been measured. The crystal structures of 1-benzoylindole and 9-benzoylcarbazole have been determined by X-ray crystallography and the corresponding 13C NMR spectra in the solid state have been measured by the CPMAS technique. Whereas 1-benzoylindole presents a standard behaviour, 9-benzoylcarbazole shows an unexpected 13C CPMAS spectrum with additional splittings. In order to understand this fact, the 1H and 13C NMR spectra in dimethylether at -143°C (130 K) have been recorded and ab initio calculations (RHF/6-311G**) carried out. The corresponding absolute shieldings (GIAO/RHF/6-311G**) together with the X-ray structure and the 13C chemical shifts at low temperature have been used to discuss the CPMAS spectrum. We propose that the supplementary splittings of this spectrum are due to its conglomerate structure.
Nitroxide-Catalyzed Oxidative Amidation of Aldehydes to Yield N-Acyl Azoles Using Sodium Persulfate
Politano, Fabrizio,León Sandoval, Arturo,Witko, Mason L.,Doherty, Katrina E.,Schroeder, Chelsea M.,Leadbeater, Nicholas E.
supporting information, (2021/12/23)
A methodology for the oxidative amidation of aldehydes to yield N-acyl azoles is reported. The approach employs sodium persulfate and a catalytic amount of a nitroxide and is applicable to a range of structurally diverse substrates.
Oxidative Amidation of Amines in Tandem with Transamidation: A Route to Amides Using Visible-Light Energy
Nandi, Jyoti,Vaughan, Matthew Z.,Sandoval, Arturo León,Paolillo, Joshua M.,Leadbeater, Nicholas E.
, p. 9219 - 9229 (2020/08/14)
A methodology is reported for preparing amides using amines as an acyl source. The protocol involves the visible-light-promoted oxidative amidation of amines with pyrazole to synthesize N-acyl pyrazoles followed by transamidation. By combining photoredox catalysis with oxoammonium cations in the presence of sodium persulfate as a terminal oxidant, the N-acyl pyrazoles could be prepared efficiently and effectively using blue LEDs. The transamidation step was performed without the need to purify the N-acyl pyrazole intermediate, and a range of amides were generated in good to excellent yields.
Elucidation of the E-Amide Preference of N-Acyl Azoles
Takahashi, Yuka,Ikeda, Hirotaka,Kanase, Yuki,Makino, Kosho,Tabata, Hidetsugu,Oshitari, Tetsuta,Inagaki, Satoshi,Otani, Yuko,Natsugari, Hideaki,Takahashi, Hideyo,Ohwada, Tomohiko
, p. 11370 - 11382 (2017/11/10)
The conformational properties of N-acyl azoles (imidazole, pyrazole, and triazole) were examined. The N-2′,4′,6′-trichlorobenzoyl azoles were stable in methanol at room temperature, and no hydrolyzed products were observed over 7 days in the presence of 5% trifluoroacetic acid or 5% triethylamine in CDCl3. The high stability may be explained by the double-bond amide character caused by the steric hindrance due to the ortho-substituents in the benzoyl group. While specific E-amide preferences were observed in N-acyl pyrazoles/triazoles, the amides of the imidazoles gave a mixture of E and Z. One of the conceivable ideas to rationalize this conformational preference may be repulsive interaction between two sets of lone-pair electrons on the pyrazole 2-nitrogen (nN) and the carbonyl oxygen atoms (nO) in the Z-conformation of N-acyl pyrazoles/triazoles. However, analysis of orbital interactions suggested that in the case of the E-conformation of N-acyl pyrazoles, such electron repulsion is small because of distance. The interbond energy calculations suggested that the Z-conformer is involved in strong vicinal σ-σ repulsion along the amide linkage between the σN1N2 and σC1C2 orbitals in the anti-periplanar arrangement and between the σN1C5 and σC1C2 orbitals in the syn-periplanar arrangement, which lead to the overwhelming E-preference in N-acyl pyrazoles/triazoles. In the case of N-acyl imidazoles, similar vicinal σ-σ repulsions were counterbalanced, leading to a weak preference for the E-conformer over the Z-conformer. The chemically stable and E-preferring N-acyl azoles may be utilized as scaffolds in future drug design.
