A modified, economical and efficient synthesis of variably substituted pyrazolo[4,3-d]pyrimidin-7-ones

1‐Methyl‐3‐propyl‐1H‐pyrazole‐5‐carboxylic acid (3) was exclusively brominated at the 4‐position by bromine in the dark. Brominated product 8 was then converted into 1‐methyl‐3‐propyl‐1H‐pyrazole‐5‐car‐boxamide 9 by successive treatment with thionyl chloride and ammonium hydroxide. Carboxamide 9 was...

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Published in:Journal of heterocyclic chemistry 2005-09, Vol.42 (6), p.1085-1093
Main Authors: Khan, Khalid Mohammed, Maharvi, Ghulam Murtaza, Choudhary, Muhammad Iqbal, Rahman, Atta-ur, Perveen, Shahnaz
Format: Article
Language:English
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Summary:1‐Methyl‐3‐propyl‐1H‐pyrazole‐5‐carboxylic acid (3) was exclusively brominated at the 4‐position by bromine in the dark. Brominated product 8 was then converted into 1‐methyl‐3‐propyl‐1H‐pyrazole‐5‐car‐boxamide 9 by successive treatment with thionyl chloride and ammonium hydroxide. Carboxamide 9 was treated with various aroyl amides under microwave (MW) irradiation to afford 4‐aroylamino‐1‐methyl‐3‐propyl‐1H‐pyrazole‐5‐carboxamides 10‐22 and 5‐aryl‐1‐methyl‐3‐propyl‐1,6‐dihydro‐1H‐pyrazolo[4,3‐d]pyrimidin‐7‐ones 23‐35. The 1H‐pyrazole‐5‐carboxamides 10‐22 were also converted to pyrimidinones 23‐35 either by conventional heating or by MW irradiation. However, MW irradiation method gives excellent yields in very short time.
ISSN:0022-152X
1943-5193
DOI:10.1002/jhet.5570420608