Synthesis of 2-Benzoxazinones (2H-1,4-Benzoxazin-2-ones)
A transition-metal-free alkylation and acylation of C(sp2)-H bonds in biologically relevant 2-benzoxazinones with 1,4-dihydropyridines offers excellent functional group compatibility and a broad substrate scope.
Y. Byun, J. Moon, W. An, N. K. Mishra, H. S. Kim, P. Ghosh, I. S. Kim, J. Org. Chem., 2021, 86, 12247-12256.
Efficient reactions of α-keto acids with 2-aminobenzamides, 2-aminobenzenethiols, benzene-1,2-diamines, and 2-aminophenols provide quinazolinones, benzothiazoles, quinoxalinones, and benzoxazinones under catalyst-free conditions, using water as the solvent. Products can be easily purified through filtration and washing with ethanol (or crystallized).
J. Huang, W. Chen, J. Liang, Q. Yan, Y. Fan, M.-W. Chen, Y. Peng, J. Org. Chem., 2021, 86, 14866-14882.
Cyclizations of α-phenylglyoxylic acids with ortho-functionalized anilines in deep eutectic solvents (DES) provide 2-arylbenzothiazoles (from o-aminothiophenols), 3-aryl-2H-benzo[b][1,4]oxazin-2-ones (from o-aminophenols), and 3-arylquinoxalin-2(1H)-ones (from o-phenylenediamines) without the addition of other catalysts. The title compounds were obtained in good yields under mild conditions.
G. Jiang, G. Chen, J. Yang, H. Li, Z. Chen, Z. Xie, Z. Le, Synthesis, 2022, 54, 3069-3076.