CON(C)C([C:6]1[CH:14]=[C:13]2C(C(C)=C[N:12]2[CH2:15][C:16]2[CH:21]=CC(OC)=[CH:18][CH:17]=2)=CC=1)=O.C([Li])CCC.CN(C)C=[O:34].[Cl-].[NH4+]>C(OCC)C>[CH3:21][C:16]1[CH:15]=[N:12][CH:13]=[C:14]([CH3:6])[C:17]=1[CH:18]=[O:34]A stirred solution of 4-bromo-3,5-dimethylpyridine (3.72 g, Reference Example 25) in diethyl ether (50 ml), at −78° C. and under nitrogen, was treated dropwise with n-butyl lithium (0.025 ml, 1.6M). After stirring at −78° C. for 1 hour the resulting homogeneous solution was treated with dry dimethylformamide (6 ml) whilst maintaining the temperature below −65° C. The reaction mixture was allowed to warm to room temperature over 1 hour, then treated with a saturated aqueous solution of ammonium chloride (10 ml), and then extracted twice with ethyl acetate (100 ml). The combined extracts were evaporated to yield an orange oil which was subjected to flash chromatography on silica, eluting with a mixture of ethyl acetate and pentane (1:4, v/v) to afford the title compound (2.3 g) as a semi-solid.
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