3,5-dichloro-4-pyridinecarbonitrile: a multisite substrate for carbon nucleophiles

The reactivity of 3,5-dichloro-4-pyridinecarbonitrile (1) towards lithium or magnesium organometallic reagent is described. Conditions for substitution of cyano with alkyl or phenyl group, alkylation at the position 2 with removal of the 5-positioned chlorine, and formation of methyl or phenyl dichloropyridyl imines are reported. The obtained 4-alkyl-3,5-dichloropyridines can undergo a further alkylation at the position 2. The 3,5-dichloro-4-pyridyl residue is shown to be a good leaving group in form of anion yielding 3,5-dichloropyridine either from 1 or 3,5-dichloro-4-pyridinecarboxaldehyde.