2-Aryl-1,2,3-triazoles were synthesized by cyclization of the corresponding glyoxal arylosazones, generated from commercial arylhydrazines. The deproto-metallation of 2-phenyl-1,2,3-triazole was attempted using different 2,2,6,6-tetramethylpiperidino-based mixed lithium–metal (Zn, Cd, Cu, Co, Fe) combinations, giving results in the case of Zn, Cd, and Cu. The lithium–zinc combination was next selected to apply the deprotonation–iodination sequence to all the 2-aryl-1,2,3-triazoles synthesized. The results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method.
Ammonium bifluoride was efficiently used at a 0.5 mol% loading to catalyze the cyclocondensation of 1,2-arylenediamines with 1,2-dicarbonyl compounds at room temperature in methanol–water to give quinoxalines or pyrido[2,3-b]pyrazines in excellent yields. Importantly, 2,8-disubstituted quinoxalines and 3-substituted pyrido[2,3-b]pyrazines were regioselectively formed by the reaction of arylglyoxals with 3-methylbenzene-1,2-diamine or pyridine-2,3-diamine, respectively. An analysis of the density functional theory reactivity indices explained the catalytic role of ammonium bifluoride.
30 August 2017 in European Journal of Organic Chemistry
A series of thieno[2,3-d]- and thieno[3,2-d]pyrimidines have been easily synthesized using as key step a deproto-cadmiation–trapping sequence. Some of the compounds thus synthesized were screened for anticancer (cytotoxic) activities, and (S)-2-(6-iodo-2-phenylthieno[2,3-d]pyrimidin-4-ylamino)-3-phenylpropanoic acid proved to have a significant activity towards liver, human breast and cervix carcinoma cell lines.
Metallation of aryl ketones was achieved by using LiTMP in the presence of ZnCl 2 ·TMEDA, as evidenced by subsequent interception with iodine or by palladium-catalysed cross-coupling reaction.