38577-53-6Relevant articles and documents
NMR and semiempirical conformational analysis of the 2-aryl-1,3-dihydroxy-4,4,5,5-tetramethylimidazolidines
Alcantara, Antonio F. de C.,Pilo-Veloso, Dorila,Stumpf, Humberto O.,De Almeida, Wagner B.
, p. 16911 - 16922 (1997)
2-Aryl-1,3-dihydroxy-4,4,5,5-tetramethylimidazolidines (1) were synthesized and their 1H and 13C NMR spectra recorded. Quantum mechanical semiempirical calculations were also performed for a better understanding of the signals recorded in the NMR spectra of imidazolidines. The conformation of the imidazolidine ring was initially studied for the 2-methyl-1,3-dihydroxy-4,4,5,5-tetramethylimidazolidine (2), used as a model molecule. The results of the calculations obtained for structure 2 showed that the methyl groups are located in axial and equatorial positions. At these positions, the methyl groups are affected by the magnetic anisotropic effects of carbon-nitrogen and carbon-carbon bonds of the imidazolinyl ring with different intensities. Semiempirical calculations for structure 2, suggested that the effect of the γ-oxygen on the carbon atoms of methyl groups (γ-effect) might lead to an alteration of the electronic charge density and consequently to a change in the diamagnetic shielding on these groups. These data were used for the analysis of the NMR spectra of compound 1. The diamagnetic shielding effects, estimated from the calculated electronic charge densities on the carbon atoms of methyl groups, are in agreement with the signals observed in the NMR spectra of compound 1. By combining the contribution of the anisotropic and γ-effects, it appears that the axial methyl groups are located relatively closer to the γ-oxygens in compound 1.
Transformation of 1,2,3,7a-tetrahydroimidazo[1,2-b]isoxazole derivatives into isoxazoles
Chukanov,Popov,Romanenko,Reznikova
, p. 1227 - 1233 (2008/09/19)
The reactions of 1,2,3,7a-tetrahydroimidazo[1,2-b]isoxazole derivatives with electrophilic reagents, such as protic acids, benzoyl chloride, BF 3, and bromine, produce isoxazole, 2,2,3,3-tetramethylaziridine, and 2,3,3-trimethylpropen-2-ylamine
Novel 2-substituted nitronyl nitroxides as free radical scavengers: Synthesis, biological evaluation and structure-activity relationship
Wu, Yihui,Bi, Lanrong,Bi, Wei,Li, Zeng,Zhao, Ming,Wang, Chao,Ju, Jingfang,Peng, Shiqi
, p. 5711 - 5720 (2007/10/03)
To develop more potent small molecules with enhanced free radical scavenger properties, we designed and synthesized a series of nitronyl nitroxide derivatives 4a-h. A lead compound 4f was discovered based on Ach-induced vascorelaxation assay. Further chemical modification based on this scaffold provided a new series of 2-substituted phenylnitronyl nitroxide derivatives 6a-s. The newly synthesized compounds 6a-s possess improved radical scavenger's activity based on PC12 cell survival assay. Compounds 6g,n,o, and s are some of the most potent compounds in terms of NO, H2O2, and OH scavenging ability. 2-Substitued phenylnitronyl nitroxides had a higher radical scavenging activity with the electron-donating group (EDG). In contrast, the introduction of electron-withdrawing group (EWG) to the aromatic ring led to a dramatic decrease in its radical scavenging activity. These results suggest that the electron-donating group (EDG) of the aromatic ring may be an important factor influencing the radical scavenging behavior of these compounds, and the potency of free radical scavenging activity largely depended on the position and electronic properties of the phenyl ring substituents. The enhanced radical scavenging capacities of the novel 2-substituted nitronyl nitroxides may be potential drug leads against the deleterious action of ROS (reactive oxygen species)/RNS (reactive nitrogen species).
