86259-64-5Relevant academic research and scientific papers
Synthesis of 5-alkyl-5-aryl-1-pyrroline N-oxides from 1-aryl-substituted nitroalkanes and acrolein via Michael addition and nitro reductive cyclization
Xu, Jingjing,Li, Xingyao,Wu, Jinlong,Dai, Wei-Min
, p. 6384 - 6391 (2015/03/30)
A general method for accessing 5-alkyl-5-aryl-1-pyrroline N-oxides (AAPOs) has been established using readily available aryl bromides, nitroalkanes, and acrolein as the starting materials. The palladium-catalyzed arylation of nitroalkanes gave the 1-aryl-substituted nitroalkanes, which underwent the Et3N-catalyzed Michael addition with acrolein at room temperature to afford the 4-aryl-4-nitroaldehydes. The latter were then subjected to the nitro reductive cyclization using Zn-HOAc in EtOH at 0 °C followed by warming the reaction mixture to room temperature for 24 h, furnishing the 5-alkyl-5-aryl-1-pyrroline N-oxides in good overall yields. Selected examples of 1,3-dipolar cycloaddition of the cyclic nitrones with methyl methacrylate were also described.
Azethoxyl Nitroxide Spin-Labeled Crown Ethers and Cryptands with the N-O. Group Positioned near the Cavity
Keana, John F. W.,Cuomo, John,Lex, Laszlo,Seyedrezai, Seyed E.
, p. 2647 - 2654 (2007/10/02)
We report the synthesis and complexation properties of several nitroxide spin-labeled crown ethers and cryptands in which the N-O. group, in certain conformations, is thrust toward the cavity of the molecule.While initial approaches involving the cyclization of various unsymmetrically substituted tetraethylene glycols (e.g, 10, 11, and 15) were not promising, success was achieved by the sequential addition of substituted phenyl groups to nitrone 28, leading to nitroxide crown ethers 37 and 38.Nitroxide cryptand 60 was prepared by diacylation of diaza-18-crown-6 51 with azethoxyl nitroxide diacid chloride 57 followed by reduction.The ESR spectrum aN values of these nitroxides were not sensitive to the presence of K+, Na+, or Li+ in MeOH, While diaza-18-crown-6, decamethylene cryptand 55, and nitroxide cryptand 60 formed 1:1 complexes with NaBPh4 in CDCl3, nitroxide crown ethers 37 and 38 and amide 54 did not.Adaption of the quantitative methodology of Cram et al. showed that 55 and 60 bind Na+ somewhat better than dicyclohexyl-18-crown-6.K+ is bound better than Na+ by 55 and 60, tough not as strongly as dicyclohexyl-18-crown-6.The binding of K+ and Na+ by 37 and 38 is minimal.
