ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
New Pyrazol Derivatives. IV. Preparation and Cyclization of Some Acceptor-Substituted N-(Pyrazol-3-yl)-thioureas.3-Aminopyrazol-4-carboxylic acid derivatives (1, 2) were transformed by reaction with different isothiocyanates R2NCS to N-(pyrazol-3-yl)-N. -substituted thioureas (5,6).Ethyl 3-amino-1-benzylpyrazol-4-carboxylate reacts with CSCl2 to form ethyl 1-benzyl-3-isothiocyanatopyrazol-4-carboxylate (3) which yields with amines the corresponding N-(pyrazol-3-yl)-N. -substituted thioureas (5). As a byproduct in the reaction with CSCl2 N,N. -di-(pyrazol-3-yl)-thiourea (4) is formed. With hydrazine or phenylhydrazine N-(pyrazol-3-yl)-thiosemicarbazides (7a,b) are obtained.The thioureas (5,6) can be cyclized in basic solution to 4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidin-4-on-6-thiones (8) which on alkylation form 6-alkylthio-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-ones (9). Methyl-N-(pyrazol-3-yl)-N.-benzoylisothiourea (10) reacts with ethylamine to form N-benzoyl-N. -ethyl-N‥-(pyrazol-3-yl)-guanidine derivative (11) which on treatment with NaH in dimethylformamide yields 6-benzoylamino-5-ethyl-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-one (12).By treatment with sulfuric acid the N-(pyrazol-3-yl)-thiourea derivatives (5,6) form new 6-amino substituted pyrazolo[3,4-d][1,3]thiazin-4-ones (13).
Additional Material:
5 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19913330309
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