Br[C:2]1[CH:3]=[N:4][CH:5]=[C:6]([Br:9])[C:7]=1[CH3:8].C([Li])CCC.[C:15](=[O:17])=[O:16].O>C1COCC1.CCCCCC>[Br:9][C:6]1[CH:5]=[N:4][CH:3]=[C:2]([C:7]=1[CH3:8])[C:15]([OH:17])=[O:16]
Under argon, a solution of 3,5-dibromo-4-methylpyridine (intermediate 10.1, 2.51 g, 10 mmol) in anhydrous THF (100 ml) is reacted at a temperature of −100° C. with a solution of n-butyllithium in hexane (1.6N, 6.5 ml). The reaction mixture is stirred for 15 min and then dry ice is added. The temperature is kept for 15 min at −85° C., for 1 h 30 min at −78° C. and for 2 h at room temperature. Water is added. The solvents are evaporated under vacuum and the residue is purified, eluting on diol grafted silica with MeOH.
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