Potassium Nitrate → ethyl 9',10'-difluoro-8'-nitro-7'-oxospiro[cyclobutane-1,3'(2'H)-[7H]pyrido[1,2,3-de][1,4]benzoxazine]-6'-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of ethyl 9′,10′-difluoro-7′-oxospiro[cyclobutane-1,3′(2′H)-[7H]pyrido[1,2,3-de][1,4]benzoxazine]-6′-carboxylate (580 mg, 1.73 mmol) in concentrated H2SO4 (7 mL) was treated portion wise at 0° C. with solid KNO3 (245 mg, 2.42 mmol). The reaction mixture was stirred for 1 hour at 0° C. and poured into ice-water. The resulting precipitate was collected by filtration, washed with water and dried to yield the title compound (600 mg, 91%) as a pale yellow solid. 1H-NMR (400 MHz, DMSO-d6) δ 1.30 (3H, t, J=7.3 Hz), 1.93-2.09 (2H, m), 2.16-2.25 (2H, m), 2.73-2.80 (2H, m), 4.26 (2H, q, J=7.3 Hz), 4.69 (2H, s), 8.87 (1H, s). ESIMS (+): 381 [M+H]+.

Provenance & Evidence