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