A. F. A. Shalaby

Novel Rearrangement of 5-Arylazo-2-thiohydantoin Derivatives with Alkali and Aromatic Amines

Abstract 5-Arylazo-2-thiohydantoin derivatives (2a,c) were cleaved and rearranged by aqueous sodium hydroxide to give the corresponding 1-aryl-⊿2-1,2,4-trazole-5-imino-3-carboxylic acids (3a-c). 3 a was decarboxylated to 1-phenyl-⊿2 -1,2,4-triazoline-5-imine (5). Hydrolysis of 5-arylazo-1-phenyl-2-thiohydantoins (6a-c) behaved in different manner affording 1-aryl-4-phenyl-⊿2 -1,2,4-triazoline-5-thione-3-carboxylic acids (7a-c). Fusing (2a-c) with aromatic amines at high temperature gave the corresponding anilides (8a-h). Treatment of 5-arylidene-2-thiohydantoin derivatives (9a-c) with hydrazine hydrate gave colourless products of thioureido cinnamic acid hydrazide derivatives (10a-c), while refluxing 5-arylidene-2-methylmercaptohydantoin (11a-d) with hydrazine hydrate and/or benzo-phenone hydrazone gave the corresponding glycocyamidine derivatives (12a-g).

Reactions with 2-Thiohydantoin, Synthesis of Imidazothiazolone Derivatives and Mannich Bases of 5-Arylidene-2-thiohydantoin

Treatment of 5-arylidene-2-thiohydantoin (1a-d) with alkyl bromoacetate and chloroacetic acid gave the esters 2a-f and the acids 2g-j, respectively. 2a was refluxed with concentrated hydrochloric acid to give 5-benzylidene hydantoin. 2 was cyclized with acetic anhydride to give the bicyclic product 3. 5-Arylidene-2-thiohydantoin derivatives (1a, b) and (8a) condense with formaldehyde and primary or secondary amines to give the corresponding Mannich bases 6a-f and 8c-e, respectively. The assigned structure 6 and 8 finds support from the chemical evidences

Chemical Reactivity of 2-Thiohydantoin Derivatives

Treatment of 5-arylazo-2-thiohydantoins (2 a-c) with formaldehyde and the appropriate amine in ethyl alcohol led to the formation of the corresponding Mannich bases 3a-i. 2 a-c reacted with methyl bromoacetate and/or chloroacetic acid to give the esters 5 a-c and/or the free acids 5d-f, respectively. 5e also obtained by treating 5 b with aqueous sodium hydroxide (2%). 5 a-c were cyclised with acetic anhydride to give the bicyclic products 6 a-c. 5-Arylidene-2-thiohydantoins (7 a-e) reacted with acrylonitrile in pyridine to give 5-arylidene-3-β-cyano-ethyl-2-thiohydantoins (8a-e). 8 a-c were hydrolysed with a mixture of acetic-hydrochloric acid to give the corresponding acids 8f-h. Compounds 8a, b, d were alkylated with alkyl halides to give 10 a-e which when hydrolysed with acids gave compounds 13 a-c.

REACTIONS WITH 5-ARYLAZO- AND 5-ARYLIDENE-4-THIOHYDANTOIN DERIVATIVES

5-Arylazo-3-phenyl-4-thiohydantoins (IIa-g) have been prepared and then treated with primary aromatic amines to afford the corresponding 5-arylazo-4-arylimino-3-phenyl hydantoins (VIIa-c). 3-Phenyl-4-thiohydantoin reacted with aromatic aldehydes in the presence of glacial acetic acid and fused sodium acetate to give 5-arylidene-3-phenyl-4-thiohydantoin derivatives (VIIIa-e). In the coloured arylidene derivatives (VIII,a d, e) on treatment with alkyland/or arylmagnesium halide addition occurs to the exocyclic double bond to give the products (IXa-e). The Grignard product (Xa) was oxidised with a mixture of chromic acid in glacial acetic acid to give phenyl parabanic acid and ethyl phenyl ketone.

NOVAL REARRANGEMENT OF 5-ARYLAZO-2-THIOHYANTOIN DERIVATIVES WITH ALKALI AND AROMATIC AMINES

Abstract Treatment of 5-arylazo-2-thiohydantoins with aqueous sodium hydroxide affected hetero-ring opening followed by recyclization via the loss of hydrogen sulphide with the formation of 1-aryl-Δ2 -1, 2, 4-triazole-5-imino-3-carboxylic acids.