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Synthesis of pyrano[3,4‐ c ]pyrazole and pyrazolo[3,4‐ d ][1,2]diazepine derivatives
Author(s) -
Migliara Onofrio,
Sprio Vincenzo
Publication year - 1981
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570180208
Subject(s) - chemistry , thionyl chloride , pyrazole , acetic acid , hydrazine (antidepressant) , hydrochloric acid , yield (engineering) , hydrate , hydrolysis , oxime , medicinal chemistry , acetyl chloride , ethanol , acetic anhydride , phenacyl bromide , hydroxylamine , chloride , organic chemistry , catalysis , chromatography , materials science , metallurgy
By the action of thionyl chloride on 3(5)‐ R ‐4‐phenacylpyrazole‐5(3)‐carboxylic acid ( 3c,d ), 3‐ R ‐5‐phenylpyrano[3,4‐ c ]pyrazole‐7‐(1 H )ones ( 4c,d ) were obtained. When 4c,d were treated with hydrazine hydrate followed by refluxing in ethanol containing acetic acid, 4,7‐dihydro‐3‐ R ‐5‐phenylpyrazolo[3,4‐ d ][1,2]‐diazepin‐8‐(1 H )ones ( 6c,d ) were formed. Compounds 6c,d , in turn, were refluxed in ethanol saturated with hydrochloric acid to yield 6‐amino‐1,6‐dihydro‐3‐ R ‐5‐phenyl‐7 H ‐pyrazolo[3,4‐ c ]pyridin‐7‐ones ( 7c,d ). Compounds 7c,d could be obtained directly from 5c,d. The starting materials 3c,d were prepared by hydrolysis of the oxime of 3(5)‐ R ‐4‐phenacyl‐5(3)carboalcoxypyrazoles ( 1a,b ). Structural assignments rested on correct elemental analysis, molecular weights determined by mass spectrometry, and spectroscopic evidence.