Intermolecular cyclization of pyrimidinethiol 1 with ethyl chloroacetate and chloroacetonitrile furnished thieno[2,3-d]pyrimidines 2a,b. Hydrazinolysis of o-aminoester 2a gave acid hydrazide 3, which was cyclized with various electrophilic reagents including formic acid, triethyl orthoformate, acetic anhydride, p-chlorobenzaldehyde then triethyl orthoformate, carbon disulfide, and acetylacetone affording thienopyrimidine derivatives 4-10. Another thienopyrimidine series could be obtained via treatment of o-aminocarbonitrile 2b with a variety of reagents giving derivatives 11-17. The fluorescent measurements for a group of the synthesized compounds at room temperature demonstrated high fluorescent properties.