New Furopyridines Containing Pyridoxal and Pyrazolone Fragments
作者:L. K. Kibardina、A. V. Trifonov、A. R. Burilov、M. A. Pudovik
DOI:10.1134/s1070363218090098
日期:2018.9
Reactions of pyridoxal hydrochloride with 5-pyrazolone derivatives in alcohol medium in the presence of concentrated hydrochloric acid led to the formation of new pyrazolones with pyridoxal fragments in the molecule. The corresponding diarylmethanes were formed when using pyridoxal and pyrazolone in a 1: 2 ratio.
The unusual formation of 1-acyl-1,2-dihydro-3H-pyrazol-3-ones starting from 3-acyloxypyrazoles by Fries-type rearrangement is described. Under normal conditions, acylation of 2,4-dihydro-3H-pyrazol-3-ones 1 and 2 with acid chlorides or anhydrides in the presence of triethylamine gave the corresponding 3-acyloxypyrazoles 3a-f and 4a-f. Treatment of 3a-c and 4a-f with Lewis acid, e.g. titanium(IV) chloride