Microwave and thermal heterocyclization of N,N -disubstituted hydrazinecarbothioamide 1a,b and substituted thioureidoethylthioureas 2a-c as well as 1-phenyl-3[2-(3-phenylthio-ureido)phenyl]-thiourea 6 are reported. C

Reactions of N,N′-disubstituted hydrazinecarbothioamides 8a-c and substituted thioureidoethylthioureas 9a-c with 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil, 10a) and 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, 10b) to form N,N′-disubstituted [1,3,4]thiadiazole-2,5-diamines 11a-c, 6,7-dichloro-3-substituted amino-1H-benzo[1,3,4]-thiadiazine-5,8-diones 12a-c, 2,3,7,8-tetrahalothianthrene-1,4,6,9-tetraones 13a,b, 5,6,8-trihalo-7-oxo-3,7-dihydro-2H-quinoxaline-1-carbothioic acid substituted amides 14a-c, 15a-c and 7-substituted imino-[1,3,6]thiadiazepane-3-thiones 16a-c are reported. Rationales for the observed conversions are presented.

N,N’-Disubstituted hydrazinecarbothioamides 6a - c and substituted thioureidoethylthioureas 12a - c react with ethenetetracarbonitrile (TCNE) in ethyl acetate or chlorobenzene to form the derivatives of pyrazole 7, 8; thiadiazole 10, 11 thiadiazepine 9, thiadiazepane 13, imidazolidine 14 and diazepine 15.

Ring closure reactionsRing closure reactions O 0130 Thermolysis of Symmetrical Dithiobiurea and Thioureidoethylthiourea Derivatives. -Microwave heating or pyrolysis of the title thiourea derivatives (I), (VI) and (IX) results in intramolecular heterocyclization processes furnishing various N,S-heterocycles. Application of microwave irradiation provides higher yields in comparison with yields obtained by thermal processes. -(HASSAN*, A. A.; MOURAD, A.-F. E.; EL-SHAIEB, K. M.; ABOU-ZIED, A. H.; DOEPP, D.; Heteroat. Chem. 14 (2003) 6, 535-541; Dep. Chem., Fac. Sci.,

1‐Acylthiosemicarbazides 9a‐d reacted with ethenetetracarbonitrile (TCNE, 2) in ethyl acetate with formation of N′‐(4‐amino‐5,6‐dicyano‐2H‐1,3‐thiazin‐2‐ylidene) substituted hydrazide 10a‐d, N′‐(5‐amino‐3,4‐dicyano‐2H‐pyrrol‐2‐ylidene)‐2‐substituted hydrazide 11a‐d and 2‐substituted imidazo[2,1‐b][1,3,4]‐oxadiazole‐5,6‐dicarbonitrile 12a‐d. Rationales for the conversions observed are presented.