2,4-Dichlorothiazole synthesis
- Product Name:2,4-Dichlorothiazole
- CAS Number:4175-76-2
- Molecular formula:C3HCl2NS
- Molecular Weight:154.02
2295-31-0
4175-76-2
The general procedure for the synthesis of 2,4-dichlorothiazole from 2,4-thiazolidinedione was as follows: 2,4-thiazolidinedione (50 g, 0.43 mol) was dissolved in phosphorus trichloride (240 mL) and cooled to 5 °C. Pyridine (34 mL, 0.43 mol) was added slowly over 15 minutes. The reaction mixture was heated to 125°C and maintained at this temperature for 4 hours. After completion of the reaction, it was cooled to 22°C. Excess phosphorus trichloride was removed by vacuum distillation. The residue was slowly poured into water (1 L) pre-cooled to 5°C. The aqueous phase was extracted with dichloromethane (3 x 400mL). The organic phases were combined and the solvents were evaporated to give the target product 2,4-dichlorothiazole (50 g, 76% yield).EI/MS m/z: (35Cl35Cl/35Cl37Cl/37Cl37Cl)153/155/157(M+1)+.
2295-31-0
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4175-76-2
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Yield: 76%
Reaction Conditions:
with pyridine;trichlorophosphate at 5 - 125; for 4.25 h;
Steps:
18
2,4-dichlorothiazoleCool to 5 0C a mixture of thiazolidine-2,4-dione (50 g, 0.43 mol) in phosphorus oxychloride (240 mL) and add pyridine (34 mL, 0.43 mol) over 15 min. Heat the mixture to 125 0C for 4 h and then cool to 22 0C. Remove the excess phosphorus oxychloride by vacuum distillation and add the residue to water (1 L) chilled to a temperature of 5 0C. Extract the mixture with methylene chloride (3 x 400 mL). Combine the organic portions and evaporate the solvent to afford the title compound (50 g, 76%). EI/MS m/z : (35C135C1/35C137C1/37C137C1) 153/155/157 (M+l)+.
References:
ELI LILLY AND COMPANY WO2008/36579, 2008, A1 Location in patent:Page/Page column 36-37