Pipecolic Acid → 2-(4-chloro-2-fluoro-5-isopropoxyphenyl)-5,6,7,8-tetrahydroimidazo[1,5-a]pyridine-1,3(2H,8aH)-dione

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Reaction Conditions

Reaction Steps

A solution of 4-chloro-2-fluoro-5-isopropoxyphenyl isocyanate (2.3 g) in chlorobenzene (10 ml) was added to a 2% aqueous solution of sodium hydroxide (25 ml) containing pipecolic acid (1.3 g), and the mixture was stirred at room temperature (ca. 20° C.) for 3 hours. After allowed to stand overnight, the precipitated crystals were collected by filtration and washed with ether. The crystals were combined with water (20 ml) and adjusted to pH 2 or less with hydrochloric acid, followed by reflux for 3 hours. After allowed to cool, the mixture was extracted with ether, dried and concentrated. The residue was purified by silica gel chromatography to give 0.6 g of 2-(4-chloro-2-fluoro-5-isopropoxyphenyl)-5,6,7,8-tetrahydroimidazo[1,5-a]pyridine-1,3(2H,8aH)-dione (Compound No. 7). M.P. 60.5°-64.5° C.

Provenance & Evidence