A number of 2‐thioxopyrido[3′,2′:4,5]thieno[3,2‐H]pyrimdin‐4(3H‐ones (5) have been synthesized by cyclocondensation of 2‐carbethoxy‐3‐amino‐4‐phenyl‐6‐substituted‐thieno[2,3‐b]pyridines (3) with various isothiocyanates. Compounds 5 were S‐methylated routinely and the reactions compared under solid‐liquid phase transfer conditions to obtain 2‐methylthiopyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidin‐4(3H)‐ones (6). The new triheterocyclic pyridothienopyrimidines were prepared with the objective to study their pharmacological properties.

The results revealed that the ferrocene incorporation to guanidines enhances their DNA binding ability. A similar trend was found in antioxidant and antimicrobial studies. Being the bioactive molecules these compounds are potential drug candidates.

The aminothienopyridine (I) undergoes ring closure reaction with the isothiocyanates (II) to give the pyrimidines (III).

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Synthesis and S-Methylation of 2-Thioxopyrido(3',2':4,5)thieno(3,2d) pyrimidin-4(3H)-ones with and without a Phase Transfer Catalyst. -A series of new pyridothienopyrimidines (III) (14 examples) are prepared by cyclocondensation of 2-ethoxycarbonyl-3-aminothienopyridines (I) with isothiocyanates with the objective to study their pharmacological properties. The S-methylation of the title compounds (III) is significantly more efficient in the presence of a phase transfer catalyst. -(DAVE, C. G.; SHAH, A. B.; SHAH, H. C.; J. Heterocycl. Chem. 34 (1997) 3, 937-940; Chem. Sci. Lab., Loyola Cent. Res. Dev., St. Xavier's Coll., Ahmedabad 380 009, India; EN)