Yield:85462-59-5 83%

Reaction Conditions:

with pyridine;bromine in dichloromethane; for 1 h;Cooling with ice;

Steps:

25.1 Example 25: Preparation of Compound 59Step 1

To a solution of Compound 56 (5g, 34.3mmol) in dichloromethane (60mL) was added pyridine (4.2ml, 51.5mmol)under ice-cooling, dropwised a solution of bromine (1.8ml, 34.3mmol) in dichloromethane (40mL), the solution wasstirred for 1 hour. To the reaction mixture was added sodium thiosulfate aqueous solution, and extracted with ethylacetate. The organic layer was dried with anhydrous sodium sulfate, and concentrated under reduced pressure. Theresidue was purified by silica gel chromatography (ethyl acetate / hexane) to yield Compound 57 (6.4g, yield: 83%) asan orange solid.LC-MS: m/z=223. [M+H]+

References:

EP3112369,2017,A1 Location in patent:Paragraph 0296; 0297