Isolation of the Half-Condensed Pyrazoline Intermediates en Route to N-(1,10-Phenanthroline)-pyrazole Derivatives from the Knorr Reaction
摘要:
During the synthesis of 2-pyrazole-1,10-phenanthroline derivatives by the Knorr reaction from benzoylacetone and 2-hydrazine-1,10-phenanthroline, three half-condensed intermediates, the 5-hydroxyl pyrazolines (2b-2d), were isolated and characterized by NMR spectroscopy and x-ray diffraction (for 2b and 2d). These pyrazoline intermediates could be readily dehydrated under the catalysis of acetic acid to afford the corresponding pyrazoles with high regioselectivity.
Isolation of the Half-Condensed Pyrazoline Intermediates en Route to N-(1,10-Phenanthroline)-pyrazole Derivatives from the Knorr Reaction
摘要:
During the synthesis of 2-pyrazole-1,10-phenanthroline derivatives by the Knorr reaction from benzoylacetone and 2-hydrazine-1,10-phenanthroline, three half-condensed intermediates, the 5-hydroxyl pyrazolines (2b-2d), were isolated and characterized by NMR spectroscopy and x-ray diffraction (for 2b and 2d). These pyrazoline intermediates could be readily dehydrated under the catalysis of acetic acid to afford the corresponding pyrazoles with high regioselectivity.