Water → 7-Fluoro-6-nitro-4-(prop-2-yn-1-yl)-2H-1,4-benzoxazin-3(4H)-one

Participants

Reaction Steps

To a stirred solution of the compound of Step C, Example 3, (4.0 gm, 18.86 mmol) in DMF (100 mL), under N2, at 5° C. (ice-bath) was added sodium hydride (60% in mineral oil, 753.0 mg, 18.86 mmol) portionwise. When gas evolution stopped, propargyl bromide (80%, 2.24 gm, 18.86 mmol) was added dropwise. The dark solution was stirred at room temperature for 17 hours. The reaction was carefully poured into water (150 mL) and EtOAc (600 mL) was added. The organic layer was separated and evaporated to dryness. The residue was chromatographed on silica gel using 25% of ethyl acetate in hexane as eluent. Fractions of compound of interest were combined and evaporated to dryness to yield the title compound of Step D, Example 3, as a yellow solid (2.7 gm), 57%; m.p. 105°-107° C.; IR (nujol, cm-1): 1695.3 (C=O) and 2120.6 (C≡C); 1H NMR δ: 4.76-4.81 (m,4H), 6.91-6.94 (d,1H), 7.97-7.98 (d,1H), 2.35 (s,1H).

Provenance & Evidence