Br[C:2]1[CH:7]=[CH:6][C:5]([Cl:8])=[CH:4][N:3]=1.C([Li])CCC.CN(C)[C:16](=[O:18])[CH3:17].Cl>C(OCC)C.C1COCC1.O>[C:16]([C:2]1[CH:7]=[CH:6][C:5]([Cl:8])=[CH:4][N:3]=1)(=[O:18])[CH3:17]
To a suspension of 56 g of 2-bromo-5-chloropyridine in 560 ml of dry diethylether is added a solution of 179 ml of n-butyllithium (15% solution in hexane) at -78° and under argon at such a rate that the temperature never exceeds -72°. Immediately thereafter the solution of 25.7 ml of N,N-dimethylacetamide in dry THF is added. The mixture is stirred for one hour at the same temperature and thereafter decomposed by careful addition of 100 ml of 3N hydrochloric acid, followed by 100 ml of water with vigorous cooling. Working up by process A (see Example 1) and purification by chromatogrphy over silica gel (toluene/ethyl acetate=20/1) yields the compound as white needles; m.p.: 58°-65°.
Wird geladen…
