Urea → 1,3-Dihydro-5-isobenzofuranol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

1,3-Dihydro-2-benzofuran-5-amine (prepared according to U.S. Pat. No. 4,000,286) (2.7 g, 20 mmol) was dissolved in a mixture of water (300 mL) and conc. H2SO4 (21 mL), cooled to 0° C. and NaNO2 (1.43 g, 20.7 mmol) in water (10 mL) was added over 15 min. After stirring at 0° C. for 1 h the mixture was allowed to stir at 10° C. for 30 min and urea was added until a negative test with starch/KI paper was observed. The solution was then poured over 2 min into a mixture of water (180 mL) and conc. H2SO4 (12.6 mL) at 90° C. and stirred at this temperature for 1.5 h. The hot mixture was filtered then allowed to cool to room temperature. The aqueous mixture was extracted with EtOAc (2×100 mL) and the combined organic layers were dried (MgSO4) and evaporated to give the title phenol (974 mg, 36%) as a cream solid; δH (CDCl3, 400 MHz) 5.03 (4H, s), 6.71 (2H, m), 7.08 (1H, d).

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