4175-77-3

2295-31-0

4175-77-3

General procedure for the synthesis of 2,4-dibromothiazoles from 2,4-thiazolidinediones: Example 41: Preparation of 2-amino-3-methyl-5-(3-pyrimidin-5-ylphenyl)-5-(1,3-thiazol-4-yl)-3,5-dihydro-4H-imidazol-4-one Step a) Preparation of compound 2 A mixture of 2,4-thiazolidinedione 1 (2.28 g, 19.5 mmol) with phosphorus tribromide (25.0 g, 87.0 mmol) was heated at 130°C for 30 min and subsequently cooled to room temperature. The reaction mixture was diluted with ice water (300 mL) and neutralized by batchwise addition of solid sodium carbonate. After neutralization was complete, the mixture was extracted with dichloromethane (3 x 150 mL). The organic layers were combined, dried over anhydrous sodium sulfate, filtered and concentrated. The residue was purified by fast column chromatography (silica gel, elution gradient: 0:100 to 5:95 ethyl acetate/hexane) to afford compound 2 (3.34 g, 71%) as light yellow crystals.1H NMR (500 MHz, CDCl3) δ 7.21 (s, 1H).