Heterocyclic compounds containing nitrogen and sulfur play a key role in medicinal chemistry owing to their immense pharmacological potential. Among the Sulfur and Nitrogen heterocycles 5-memebered are more important. Therefore, here an attempt has been made for synthesis of Thiophene fused arylbenzo[4,5]thieno[2,3-d]thiazole derivatives. These heterocycles have been prepared using a facile, cheap and one-pot catalytic method from 2-(2-bromophenyl)acetonitrile, substituted hetero-aromatic aldehydes, and sulfur powder. The reactions preceded in the presence 1,10- phenonthroline, K₂CO₃ and Cu(I)Cl in DMSO. Eight new thiophen-thaizole derivatives have been synthesized, purified and herein coded as IMA-R1, IMA-R2, IMA-R3, IMA-R4, IMA-R5, IMA-R6, IMA-R7 and IMA-R8 (Table 1). These synthesized thiophen-thaizole heterocycles were characterized using different spectroscopic techniques, like ¹HNMR, ¹³CNMR, FT-IR, UV-Visible and spectrofluorimetry. ¹HNMR spectroscopic data revealed that all the characteristic peaks that indicated the formation of the expected fused thiophene-thiazole compounds (Table 2). Similarly, the ¹³C chemical shift values were in good agreement to the proposed molecular structures of the synthesized thiophen-thaizole heterocycles (Table 3). The λ_max values were found in range of 282-315 nm assignable to the conjugated system. The λ_max values and the spectrofourimetric emission patterns of the compounds are in accordance to the electronic properties of the substituents. FTIR spectroscopic analysis revealed the characteristic bands including a C-S stretching vibration peak which showed the formation of the desired compounds (Fig. 1).. Results of the above mentioned spectroscopic techniques have indicated the successful syntheses of the desired heterocyclic compounds.

Keywords: fused heterocyclic compounds; synthesis; spectroscopic characterization.