Investigation on the Synthesis, Application and Structural Features of Heteroaryl 1,2-Diketones

Abstract

A set of unsymmetrical heteroaryl 1,2-diketones were synthesized by a heteroarylation/oxidation sequence with up to 65% isolated yields. Palladium catalyst XPhos Pd G4 and SeO 2 were the key reagents used in this methodology, and microwave irradiation was utilized to facilitate an efficient and ecofriendly process. The application of heteroaryl 1,2-diketones is demonstrated through the synthesis of an unsymmetrical 2-phenyl-3-(pyridin-3-yl)quinoxaline ( 5a ) from 1-phenyl-2-(pyridin-3-yl)ethane-1,2-dione ( 4a ). The lowest energy conformations of 4a and 5a were located using Density Functional Theory (DFT) at the M06-2X/def2-TZVP level of theory. Two lowest energy conformations of 4a differ with respect to the position of the N atom in the pyridyl ring and 0.27 kcal/mol energy difference between them corresponds to 60.4 and 39.6% at 50 °C in toluene. Four lowest energy conformations for 5a have the energy differences of 0.01, 0.03 and 0.07 kcal/mol that corresponds to 26.0, 25.7, 24.9 and 23.4%, respectively. A comparison of 4a and 5a to the less hindered analogs (oxalyl chloride and oxalic acid) is used to investigate the structural features and bonding using Natural Bond Orbital (NBO) analysis.

Effect of para‐Substituents on meso‐Functionalized Oxidovanadium(IV) Porphyrins as Catalysts for Oxygen Atom Transfer Mediated Oxidation of Benzoin to Benzil under Mild Conditions

“…[3][4][5] It can be used to synthesize diketimines by reacting with amines. [6,7] In addition, reduced benzil derivatives are crucial intermediates for several pharmaceuticals like antibiotics, [8] antifungal, [9] antidepressants, [10] urease inhibitors, [11] and selective inhibitors for the β-protein of amyloid. [12] Moreover, benzil is the main substrate for the classical benzilic acid rearrangement, and its esters are used to synthesize A-norpreganes derivatives having biological properties.…”

“…Benzil is also useful as a photosensitizer in UV–curing resin, an intermediate in pharmaceuticals, a photoinitiator in polymer chemistry, and a potent inhibitor of human carboxylesterases [3–5] . It can be used to synthesize diketimines by reacting with amines [6,7] . In addition, reduced benzil derivatives are crucial intermediates for several pharmaceuticals like antibiotics, [8] antifungal, [9] antidepressants, [10] urease inhibitors, [11] and selective inhibitors for the β‐protein of amyloid [12] …”