SYNTHESIS OF 4-ALKYL-3,5-DIBROMOPYRIDINE, 3-BROMO-4,5-DIALKYLPYRIDINEAND 3,4,5-TRIALKYLPYRIDINE VIA SEQUENTIAL METALATION AND METAL-HALOGEN EXCHANGE OF 3,5-DIBROMOPYRIDINE

Lithiation of 3,5-dibromopyridine with LDA and subsequent reaction wit h electrophiles provided 4-alkyl-3,5-dibromopyridines 2 in high yield. 3-Bromo-4,5-dialkylpyridines 3 were synthesized by metal-halogen exch ange of 2 with one equivalent n-BuLi and reaction with a second electr ophile. Further metal-halogen exchange of 3 and reaction with a third electrophile provided 3,4,5-trisubstituted pyridines 4. Copyright (C) 1996 Elsevier Science Ltd