Double nucleophilic addition. A new one-pot synthesis of 2-alkyl- and 2-phenyl-5-hydrazinopyridine from pyridine

A new method for the synthesis of 2-alkyl- and 2-phenyl-5-hydrazinopyridine has been developed. Nucleophilic addition on pyridine by alkyl or phenyl lithium reagents generated a 2-substituted dihydropyridine anion that reacts with di-t-butyl azodicarboxylate to form 2,5-disubstituted dihydropyridine. Conversion of the dihydropyridines to pyridines was achieved by a mild air oxidation.