4-Amino-3-pyrazolidinones

C5H5N50 6-amino-1,3-dihydro-2H-purin-2-one 3373-53-3 25.00 1.4702 2 4616 C5H7CIN202 1 -chloroacetyl-3-pyrazolidinone. .. 25.00 1.3340 2... 

Amino-3-pyrazolin-5-ones (4-imino-3-pyrazolidinones) react with nitrous acid as do ordinary aromatic amines to form diazonium salts.426,984,1353 These then couple readily with aromatic amines,1017,1018,1060 phenols992,1323 and aliphatic compounds having active hydrogen atoms,428,1017 such as acetoacetic esters. The products are 4-azo-3-pyrazolin-5-ones (eq. 200). The diazonium salts also couple... 

The 5-imino-2-pyrazolines having no N-l substituents can be acylated with acetic anhydride to form the 1-acyl derivatives,301,342,391 as can their 5-oxo analogs. Compounds of this type having a 3-acetoxy substituent have been prepared by reaction of 3-amino-2-pyrazolin-5-ones (5-imino-3-pyrazolidinones) with acetic anhydride (eq. 237).594,1598 Cusmano and Sprio343,344 have treated a-benzylidene-j8-ketonitriles... 

In the presence of sulfuric acid 1-nitroso-3-pyrazolidinones lose nitrous acid by elimination, giving 2-pyrazolin-5-ones which are then nitrosated at C-4.335,1028 The amino group in 4-amino-3-pyrazol-idinones is diazotizable and the resulting diazonium salt undergoes coupling.12... 

Synthetic methods involving conversion of other, but similar, ring systems to 3,5-pyrazolidinediones have been reduction of 1,2-diphenyl-3,4,5-pyrazolidinetrione with tin and hydrochloric acid63 and hydrolysis of 5-imino-3-pyrazolidinones (3-amino-2-pyrazolin-5-ones) with acid.1339,1596... 

The most frequently used procedures for preparation of 5-imino-3-pyrazolidines can all be considered as variations of cyclization of malonic acid derivatives. Various hydrazines react with ethyl /3-amino-/ -ethoxyacrylate to form 2-substituted-5-imino-3-pyrazolidinones (eq. 261). Complex alkyl groups,706 aryl groups693,695,922,1140,1601 and... 

In compounds which have no substituents at N-l or N-2 nuclear acylation also occurs and under some conditions acylation occurs at C-4. The use of 2-alkyl- or aryl-5-imino-3-pyrazolidinones, which exist as the 3-amino-2-pyrazolin-5-one isomer, with an equivalent of acid chloride, either aliphatic or aryl, leads to 3-acylamides (eq. 266),14,67,594,695,1247,1594,1595 although in some cases a side-reaction gives both N- and O-acylation.1595 Under the same conditions 3-hydroxy-5-imino-2-pyrazolinones give O-acylation.1599 The reaction of... 

Amino-5-imino-3-pyrazolidinones have been synthesized by reduction of the corresponding oximes.644,1339 Such amines form ureas and thioureas by reaction with potassium cyanate in acid solution and with phenyl isothiocyanate.644 4-Arylimino-5-imino-3-pyrazolidinones have been prepared by reaction of the 5-imino-3-pyrazolidinones with p-amino-A.-AT-diethylaniline in the presence of silver salts as oxidizing agents (eq. 172).244,519,1255,1538 4-Arylazo-5-imino-3-pyrazolidinones have most frequently been prepared by reaction of 5-imino-3-pyrazoli-dinones with aryldiazonium chlorides, as is usual for the preparation of similar compounds.591,594,920,1087,1255,1339,1539,1649 One such compound has been prepared by the Curtius rearrangement of the corresponding 4-arylazo azide.594... 

Amino-5-imino-3-pyrazolidinones react with formaldehyde at the 4-amino group giving methylol derivatives.644 The 4-arylimino derivatives are reduced catalytically to give 4-arylamino analogs.1538 An interesting reaction of the 4-arylazo-5-imino-3-pyrazolidinones is the replacement of the 4-arylazo group by arylimino (eq. 272).1255 1296... 

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