Isothiocyanates with 2-imino-4-thiazolines

Condensation of 2-phenyl-4-amino-5-benzoylthiazole with cyanamide yields the pyrimidothiazole (Scheme 88) (133) (49) 2-imino-3-aryl-4-amino-5-carbethoxy-4-thiazolines condense similarly with alkyl isothiocyanates (276). 

Treatment of 2-imino-3-phenyl-4-amino-(5-amido)-4-thiazoline with isocyanates or isothiocyanates yields the expected product (139) resulting from attack of the exocyclic nitrogen on the electrophilic center (276). Since 139 may be acetylated to thiazolo[4,5-d]pyrimidine-7-ones or 7-thiones (140). this reaction provides a route to condensed he erocycles (Scheme 92). 

In an extension of this work, analogous [4 + 2] and [4+1] cycloadditions of thiocarbamoyl isothiocyanates (161) have been examined. Their interaction with isocyanides under restrained conditions yields 2-amino-5-imino-2-thiazoline-4-thiones (162) as deeply coloured stable... 

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