Wehrle Robert J, Rosen Alexander, Nguyen Thu Vu, Koons Kalyn, Jump Eric, Bullard Mason, Wehrle Natalie, Stockfish Adam, Hare Patrick M, Atesin Abdurrahman, Ateşin Tülay A, Ma Lili
Department of Chemistry & Biochemistry, Northern Kentucky University, Nunn Drive, Highland Heights, Kentucky 41099, United States.
Department of Chemistry, The University of Texas Rio Grande Valley, Edinburg, Texas 78541, United States.
ACS Omega. 2022 Jul 20;7(30):26650-26660. doi: 10.1021/acsomega.2c02914. eCollection 2022 Aug 2.
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 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 () from 1-phenyl-2-(pyridin-3-yl)ethane-1,2-dione (). The lowest energy conformations of and were located using Density Functional Theory (DFT) at the M06-2X/def2-TZVP level of theory. Two lowest energy conformations of 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 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 and 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.
通过杂芳基化/氧化序列合成了一组不对称杂芳基1,2 - 二酮，分离产率高达65%。钯催化剂XPhos Pd G4和二氧化硒是该方法中使用的关键试剂，利用微波辐射促进了高效且环保的过程。通过由1 - 苯基 - 2 -（吡啶 - 3 - 基）乙烷 - 1,2 - 二酮（）合成不对称的2 - 苯基 - 3 -（吡啶 - 3 - 基）喹喔啉（）证明了杂芳基1,2 - 二酮的应用。使用密度泛函理论（DFT）在M06 - 2X/def2 - TZVP理论水平上确定了和的最低能量构象。的两个最低能量构象在吡啶环中N原子的位置上有所不同，它们之间0.27 kcal/mol的能量差对应于50℃甲苯中60.4%和39.6%的构象。的四个最低能量构象的能量差分别为0.01、0.03和0.07 kcal/mol，分别对应于26.0%、25.7%、24.9%和23.4%。通过将和与位阻较小的类似物（草酰氯和草酸）进行比较，利用自然键轨道（NBO）分析来研究其结构特征和键合。
