The reactions of heterocyclic isothiocyanates bearing an ortho ester group with N-nucleophiles. The scope and some limitations of the reaction

Heterocyclic isothiocyanates bearing an o-ester group were converted into thiourea derivatives 2, 5, 6, 7 , and 9 using sterically large primary amines or aminoacids, and to the fused ring systems, e.g. 12H-pyrido3′,2′:4,5]pyrimido2,1-b]benzothiazol-12-one ( 3 ), and 6,7-dihydro-9H-thiazolo3,2-a]thieno3,2-d]-pyrimidin-9-one ( 13 ), respectively, using bifunctional reagents such as 2-aminothiophenol or cysteamine.