Sodium Thiosulfate → 9-Bromo-2-(4-methylphenyl)-2,6-dihydro[1,2,4]triazolo[4,3-c]quinazoline-3,5-dione

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Reaction Steps

To a solution of 7a (0.534 g, 1.33 mmol) in 60 mL of CH2Cl2 was added (77%) m-CPBA (0.597 g, 2.67 mmol) and mixture was stirred at room temperature for 6 h. A white precipitate was slowly formed. Saturated solutions of aqueous Na2S2O3 (20 mL) and NaHCO3 (20 mL) were subsequently added and the mixture was stirred vigorously for 30 min. The precipitate was filtered off, washed several times with water and heated in a mixture of 25 mL ethyl alcohol and 25 mL of water at reflux for 30 min. The mixture was cooled to rt. and filtered to give 8a as a white solid (0.488 g, 99%). mp: 369° C.;

Provenance & Evidence