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

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-methoxybenzaldehyde and 4-benzoxybenzaldehyde with methyl 2-amino-6-benzyl-4,5,6,7-tetrahydrothieno[2,3- c ]pyridine-3carboxylate as precursors in ethanol medium. Pd(II) complexes (1a, 2a) were prepared using the corresponding [PdCl 2 (CH 3 CN) 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 ( 1 H and 13 C) NMR, UV- Vis spectra, FT-IR, mass, TGA and CHNS to determine their molecular structures. Finally, the results obtained based on Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions show that electrondonating 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. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, ONS-donor atom containing Schiff base ligands (1, 2) were utilized to synthesize complexes 1a and 2a. The ligands were prepared using 2-hydroxy-3-methoxybenzaldehyde and 4-benzoxybenzaldehyde with a precursor in an ethanol medium. Pd(II) complexes (1a, 2a) were then formed by reacting the corresponding [PdCl2(CH3CN)2] with the Schiff base ligands in a 1:1 molar proportion. The molecular structures of the Schiff bases (1, 2) and their Pd(II) complexes (1a, 2a) were characterized using various analytical/spectroscopic techniques. The results demonstrated that the presence of complexes 1a and 2a as catalysts could facilitate Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions, leading to high-yield coupling products.