Hydrochloric Acid → [2-Cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1-yl]acetic acid

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Reaction Steps

A solution of tert-butyl[2-cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1-yl]acetate (2.2 g, 5.8 mmol), and sodium hydroxide (1.6 g, 40 mmol) in ethanol (200 ml) was heated to reflux for 2 hours. After cooling to room temperature the mixture was acidified with diluted hydrochloric acid, and extracted with ethylacetate. The ethylacetate solution was dried over magnesium sulfate, filtered, and concentrated in vacuo. Recrystallization from ethylacetate/hexane afforded the title compound, m.p. 207-209° C. (1.2 g, 64%), 1H-NMR (DMSO-d6) δ1.61 (s, 6H), 4.77 (s, 2H), 6.35 (d, J=4 Hz, 1H), 6.98 (d, J=8.1 Hz, 1H), 7.09 (d, J=4.1 Hz, 1H), 7.26 (m, 2H), 10.43 (s, 1H), MS (APCI (−)) m/z 324 (M−H)−.

Provenance & Evidence