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Palladium(0) Catalyzed Synthesis of (<i>E</i>)-4-Bromo-<i>N</i>-((3-bromothiophen-2-yl)methylene)-2-methylaniline Derivatives via Suzuki Cross-Coupling Reaction: An Exploration of Their Non-Linear Optical Properties, Reactivity and Structural Features
oleh: Komal Rizwan, Nasir Rasool, Muhammad Ali Hashmi, Sadia Noreen, Muhammad Zubair, Mahwish Arshad, Syed Adnan Ali Shah
Format: | Article |
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Diterbitkan: | MDPI AG 2021-09-01 |
Deskripsi
A series of (<i>E</i>)-4-bromo-<i>N</i>-((3-bromothiophen-2-yl)methylene)-2-methylaniline analogs synthesized in considerable yields through Suzuki cross-coupling reactions. Various electron donating and withdrawing functional moieties were successfully incorporated under the employed reaction conditions. Reaction of 4-bromo-2-methylaniline (<b>1</b>) with 3-bromothiophene-2-carbaldehyde (<b>2b</b>) in the existence of glacial acetic acid, provided (<i>E</i>)-4-bromo-<i>N</i>-((3-bromothiophen-2-yl)methylene)-2-methylaniline (<b>3b</b>) in excellent yield (94%). Suzuki coupling of <b>3b</b> with different boronic acids in the presence of Pd(PPh<sub>3</sub>)<sub>4</sub>/K<sub>3</sub>PO<sub>4</sub> at 90 °C led to the synthesis of the monosubstituted and bisubstituted products <b>5a</b>–<b>5d</b> and <b>6a</b>–<b>6d</b> in moderate yields (33–40% and 31–46%, respectively). Density functional theory (DFT) investigations were performed on different synthesized analogues <b>5a</b>–<b>5d</b>, <b>6a</b>–<b>6d</b> to determine their structural characteristics. The calculations provide insight into the frontier molecular orbitals (FMOs) of the imine-based analogues and their molecular electrostatic potential (MESP). Reactivity descriptors like ionization energy (I), electron affinity (A), chemical hardness (<i>ƞ</i>) and index of nucleophilicity have been calculated for the first time for the synthesized molecules.