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Thiourea (4.86 g, 64 mmol) was dissolved in ethanol (60 mL) at 60° C. Methyl levulinate (4.16 g, 32 mmol) and iodine (8.11 g, 32 mmol) were added and the temperature was elevated to reflux. The mixture was stirred for 6 h and the solvent was evaporated. Ethyl acetate, water and sodium bicarbonate solution was added and mixture was extracted. The organic phase was dried (sodium sulphate), filtered and the solvent was evaporated giving 6 g crude product. The crude was flash cromatographed on SiO2 eluting with 5% methanol in DCM giving ethyl 3-(2-amino-1,3-thiazol-4-yl)propanoate (1.33 g, 7.14 mmol, 11%). This material (1.23 g, 6.14 mmol) was sulphonylated with 3-chloro-2-methylbenzenesulphonyl chloride (1.79 g, 7.98 mmol) in pyridine (5 mL) according to METHOD A giving 1.91 g (80%) of the title product: MS (Ionspray, [M+H]+) m/z 388. Anal. Calcd. (found) for C15H17ClN2O4S2: C, 46.3 (46.3)%; H, 4.4 (4.5)%; N, 7.2 (7.0)%.

1. temperatureto reflux
2. customthe solvent was evaporated
3. additionEthyl acetate, water and sodium bicarbonate solution was added
4. extractionmixture was extracted
5. dry with materialThe organic phase was dried (sodium sulphate)
6. filtrationfiltered
7. customthe solvent was evaporated
8. customgiving 6 g crude product