Synthesis of Pd+2 complexes of Schiff bases containing methyl 2-amino-6-benzyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate and spectral and catalytic activities

Abstract

Here in, ONS-donor atom containing Schiff base ligands (1, 2) was used to prepare 1a and 2a complexes. The Schiff base ligands were synthesized using 2‑hydroxy-3-methoxysalicylaldehyde and 4-benzoxybenzaldehyde with methyl 2-amino-6-benzyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate as precursors in ethanol medium. Pd(II) complexes (1a, 2a) were prepared using the corresponding PdCl2(CH3CN)2 and Schiff base in a (1:1) molar proportion. The Schiff bases (1, 2) and their Pd(II) complexes (1a, 2a) were then identified via various analytical/spectroscopic methods (1H and 13C) NMR, UV- Vis spectra, FT-IR, mass, TGA and CHN to determine their molecular structures. Finally, the results obtained based on Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions show that electron-donating and electron-withdrawing substituents on the aryl halide might produce coupling products in excellent yield in the presence of 1a, 2a complexes (as catalysts) under optimum conditions.