Dimethylformamide → 3-Chloroquinoxaline-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

From crude 16d, with a changed ratio of 1 g 16d: 0.8 mL POCl3: 1.6 mL DMF. The reaction mixture was heated, with moisture exclusion, at 75° C. for 16 h, then cooled, diluted with cold dichloromethane, and kept at −18° C. for 1 h. The brick red solid was filtered and washed exhaustively, with thorough stirring, with cold dichloromethane to give the dione (22% from 3-chloroquinoxaline-2-carboxylic acid), mp 133-139° C. 1H NMR (d6-DMSO): δ 3.27 (s, 3H, NCH3), 3.57 (s, 3H, NCH3), 7.66 (ddd, J=8.3, 6.6, 1.6 Hz, 1H), 7.81-7.92 (m, 2-H), 8.04 (d, J=7.8 Hz, 1H), 8.66 (s, 1H, ═HCNMe2). 13C NMR (d6-DMSO): δ 45.0 (CH3), 48.3 (CH3), 87.0 (C), 127.2 (CH), 128.3 (CH), 130.3 (CH), 133.3 (C), 133.7 (CH), 139.4 (C), 143.2 (C), 150.3 (C), 157.6 (C), 159.7 (C), 161.1 (CH).

Provenance & Evidence