Highly efficient one pot palladium-catalyzed synthesis of 3,5-bis (arylated) pyridines: Comparative experimental and DFT studies

Abstract

Many different alkyl and aryl substituted pyridine based organic derivatives have been synthesized due to its uniqueness pyridine core. However, the transition metal catalyzed Suzuki cross coupling reaction has provided an easy route to the synthesis of alkyl and aryl substituted pyridine based organic compounds. Herein, we reported the arylated pyridines derivatives: 3, 5-bis (4-(trifluoromethoxy) phenyl) pyridine (BTFMP), 3,5-bis(4-bromophenyl)pyridine(BBPP), 3,5-bis(4-phenoxyphenyl)pyridine (BPPP) and 3,5-bis(2,5-dimethoxyphenyl)pyridine (BDMPP) by cross coupling Suzuki methodology for the first time. All derivatives have been characterized through 1H NMR, 13CNMR, 19F NMR and FT-IR spectroscopic techniques. Two compounds (BPPP) and (BDMPP) exist in the form of crystals among studied compounds. Therefore, SC-XRD has been performed for BPPP and BDMPP. In addition, computational studies using density functional theory (DFT) have been carried out in order to compare the DFT based data with the experimental findings. The optimization, FT-IR, natural bond orbitals (NBOs), frontier molecular orbitals (FMOs) and nonlinear optical (NLO) calculations of all derivatives have been performed using B3LYP/6-311G(d,p) level. The simulated HOMO-LUMO energy difference is observed to be large which shows the kinetic stability of the molecules. The molecular stability also originating from charge delocalization and hyper conjugative interactions has been elucidated by NBOanalysis. MEP surfaces are also developed of entitled molecules. The NLO data pointed out that the first order hyperpolarizability for BTFMP, BBPP and BPPP is greater among studied molecules than the standard molecule.