3-cyano-2,6-dibromo-4-methylpyridine synthesis

Yield:38824-75-8 90%

Reaction Conditions:

with phosphorus(V) oxybromide at 190; for 2 h;

Steps:

A mixture of 2,6-dihydroxy-3-cyano-4-methylpyridine (2 g; 13.3 mmol) and phosphoryl bromide (POBre) (7.6 g; 26.6 mmol) is heated to melting point and then refluxed for 2 hours at 190°C in a flask immersed in a sand bath and then left to cool at room temperature. Ice is added to decompose the excess POBrβ and, when the ice has dissolved, the aqueous suspension is extracted with three portions of CHCI3 of 50 ml each.From the pooled chloroform extracts, dried on anhydrous Na2SO4, and evaporated, 2,6-dibromo-3-cyano-4-methylpyridine (5) is obtained. The purification of (5) is obtained by chromatography on a silica gel column (Kieselgel 60), using a product:silica ratio of 1:50 (w/w) amd using CHCI3 as the eluent phase. The only fraction that is fluxed is collected and brought to dryness, inasmuch as the various impurities are retained in the column (3.3 g; 28 mmol, yield 90%; m.p. 137-14O⁰C).

References:

WO2008/90585,2008,A2 Location in patent:Page/Page column 22; 23