Trifluoroacetic acid → 6-Fluoro-7-(methylamino)-2,3-dihydrobenzo[e][1,3]oxazin-4-one

Participants

Reaction Steps

To 3-(4-methoxybenzyl)6-fluoro-7-(methylamino)2,3-dihydrobenzo[e][1,3]oxazin-4-one (1 g, 3.5 mmol) added trifluoroacetic acid ((5 mL) and heated the reaction at 80° C. for 4 hr. RP-HPLC showed formation of new peak and disappearance of SM peak. The trifluoroacetic acid was removed under vacuum and the residue suspended in ethyl acetate and washed with saturated sodium bicarbonate solution. The ethyl acetate was dried, filtered and evaporated to afford 6-Fluoro-7-(methylamino)-2,3-dihydrobenzo[e][1,3]oxazin-4-one as off-white solid (0.500 g, 72%) after triturating with diethyl ether. RP-HPLC: 1.58 min; ES-MS (M+H)+=198.0; 1H-NMR (CDCl3) δ (ppm): 7.5 (d, 1), 6.4 (s, 1), 6.15 (d, 1), 5.17 (s, 2), 2.91 (s, 3)

Provenance & Evidence