Tunable protic ionic liquids as solvent-catalysts for improved synthesis of multiply substituted 1,2,4-triazoles from oxadiazoles and organoamines
摘要:
More than green alternatives to traditional volatile molecular organic solvents, protic ionic liquids as dual solvent-catalysts have been successfully used to promote reactions of organoamines with oxadiazoles to afford sterically hindered 1,2,4-triazoles. Among the tested protic ionic liquids, pyridinium trifluoroacetate and acetate showed the highest efficiency for the reactions of arylamines and alkylamines, respectively, indicating that tunable catalysis could be readily effected with protic ionic liquid solvent-catalysts by simply tuning their cation and anion counterparts. A general and efficient approach has been developed for synthesis of multiply substituted 1,2,4-triazoles based on the tunable protic ionic liquid solvent-catalyst systems. (C) 2012 Elsevier Ltd. All rights reserved.
Reaction of 3-formylchromone-<i>N</i>-benzoylhydrazone with ketenes. Synthesis and structural studies of chromone 1,3,4-oxadiazolines
作者:George C. Kaspentakis、Constantinos A. Tsoleridis、Julia Stephanidou-Stephanatou
DOI:10.1002/jhet.5570440223
日期:2007.3
The reaction of 3-formylchromone-N-benzoylhydrazone with ketenes, prepared in situ from the corresponding acid chlorides 2a-d and the mixed anhydride 2e was studied. In all cases 2-(4′-oxo-4′H-3′-chromyl)-5-phenyl-2,3-dihydro-1,3,4-oxadiazoles (3) were isolated in yields varying from 40 to 80%. A full structure assignment of all products has been made on the basis of 1D and 2-D (COSY H-H, COSY C-H