Quinoxalines. XXII. Aryl migration of 2-aroylquinoxalines to 2-arylquinoxalines.

Searching for Novel Inhibitors of the S. aureus NorA Efflux Pump: Synthesis and Biological Evaluation of the 3‐Phenyl‐1,4‐benzothiazine Analogues

“…Despite the fact that none of the tested compounds displayed an EtBr efflux inhibition activity against SA‐1199B similar to that of reserpine, eight of thirty compounds ( 1 d , 1 e , 3 e , 4 e , 5 b , 6 a , 6 c and 6 d highlighted in Table ) showed an activity better than that of the hit progenitor PT3; moreover, four of them ( 4 e , 5 b , 6 a , and 6 c ) were more than the twice as active as PT3 activity (Table ).…”

“…Compounds 2 a , 2 b , 2 c – e and 5 a , 5 b , 5 c , 5 d , 5 e were obtained following the procedure depicted in Scheme , by the reaction of benzene‐1,2‐diamine 11 with properly substituted 2‐bromo‐1‐phenylethanones 9 a , 9 b , 9 c , 9 d and 9 e using anhydrous sodium acetate and dry methanol. The spontaneous oxidation of the 2‐phenyl‐3,4‐dihydroquinoxaline intermediates 12 a ‐ e in the corresponding 2‐phenylquinoxaline derivatives gave compounds 5 a , 5 b , 5 c , 5 d , and 5 e . Compounds 2 a , 2 b , and 2 c ‐ e were finally obtained, after reduction in anhydrous condition of 5 a , 5 b , 5 c , 5 d and 5 e using BH 3 ⋅THF in dry THF (Scheme and Table ).…”

“…The spontaneous oxidation of the 2‐phenyl‐3,4‐dihydroquinoxaline intermediates 12 a ‐ e in the corresponding 2‐phenylquinoxaline derivatives gave compounds 5 a , 5 b , 5 c , 5 d , and 5 e . Compounds 2 a , 2 b , and 2 c ‐ e were finally obtained, after reduction in anhydrous condition of 5 a , 5 b , 5 c , 5 d and 5 e using BH 3 ⋅THF in dry THF (Scheme and Table ).…”

“…To avoid a deceptive interpretation in assigning NorA inhibitory activity and before assaying their synergistic activity with CPX, the most promising compounds of each sub‐series ( 1 d , 2 d , 3 e , 4 e , 5 b , and 6 c —Table ) were tested for potential intrinsic antibacterial activity against different S. aureus strains. The strains included S. aureus ATCC 25923 norA wild‐type (wt), SA‐K1902 in which norA gene was deleted ( norA ‐), SA‐K2378 overexpressing norA ( norA ++), and SA‐1199B ( norA +/A116E GrlA) .…”

Reaction of 2‐[(2‐Oxo‐2‐arylethyl)anilino]‐1‐aryl‐1‐ethanones with o‐phenylenediamine: Formation of quinoxalines

“…m.p. 94°C [10]); 1 H NMR (300 MHz, CDCl 3 ): 2.38 (s, 3H); 7.30(d, 2H, J = 8.4 Hz); 7.65–7.73 (m, 2H); 8.02–8.08 (m, 4H); 9.24 (s, 1H); 13 C NMR (75 MHz, CDCl 3 ): 20.4 (q), 126.4 (d), 128.0 (d), 128.2 (d), 128.5 (d), 128.8 (d), 129.2 (d), 133.0 (s), 139.5 (s), 140.4 (s), 141.3 (s), 142.3 (d), 150.8 (d).…”