Study of reactions between 1,2-diaza-1,3-butadienes and N,N '-diaryl- or N,N '-dialkylthioureas

1,2-Diaza-1,3-butadienes react with N,N'-diarylthioureas to give 2-(arylimi no)-2,3-dihydrothiazole derivatives, whereas with N,N'-dialkylthioureas to afford 5,5-disubstituted 3-alkyl-2-(alkylimino)-thiazdidin-4-one derivative s. Under basic conditions, these last products surprisingly give rise to 2- thioxo-1,3,7-triazaspiro[4.4]non-8-en-4-one and 5-oxo-4-(4-substituted 5-ox o-2-thioxoimidazolidin-4yl)-2,5-dihydro-1H-pyrazole derivatives. In acidic medium, 5,5-disubstituted 3-alkyl-2-(alkylimino)-thiazolidin-4-ones are con verted into 2-(alkylimino)-1-thia-3,7-diazaspiro[4.4]non-7-en-4-ones. X-Ray crystal structures of two products were determined. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.