3-Hydroxypyridine → Oxalate

Participants

Reaction Conditions

Reaction Steps

A screw-capped tube is charged with 2-[(3-iodophenyl)(1-methylpiperidin-4-yloxy)methyl]benzothiazole (example 41, 500 mg), copper(I) iodide (9 mg), 2,2,6,6-tetramethylheptane-3,5-dione (37 mg), cesium carbonate (701 mg), 3-hydroxypyridine (125 mg), powdered 4 Å molecular sieves (200 mg) and anhydrous N,N-dimethylformamide (1 mL). The tube is evacuated, filled with argon and sealed. After stirring at 95° C. for 2 days, the mixture is diluted with ethyl acetate, water and ammonia. After decantation, the aqueous phase is extracted with ethyl acetate. The pooled organic extracts are dried over magnesium sulfate and concentrated under reduced pressure. The residue is purified by chromatography over silica gel (gradient dichloromethane/methanol/ammonia from 98/2/0.5 to 95/5/0.5), to afford the pure base that is then converted into its oxalate salt in acetone to give 2-{(1-methylpiperidin-4-yloxy)[3-(pyridin-3-yloxy)phenyl]methyl}benzothiazole, oxalate melting at 78° C.

Provenance & Evidence