The dimerization of anils of pyridine aldehydes catalysed by cyanide ion

Abstract

The three isomeric N-(pyridylmethylene)anilines (1; Ar? = pyridyl, Ar = phenyl) dimerized in Me₂SO with NaCN to give the enediamines (2). Only when Ar? = 3-pyridyl did this spontaneously dehydrogenate to the bis(phenylimino) compound which was hydrolysed to 3,3?-pyridil. The 4- pyridyl enediamine (2; Ar? = 4-pyridyl, Ar = phenyl) formed a 1 : 1 adduct with Me₂SO. It was oxidized in poor yield to the stable bis(phenylimino) compound. The 2-pyridyl enediamine (2; Ar? = 2- pyridyl, Ar = phenyl) was oxidized with chloranil. Under standard conditions attempted dimerization of (1; Ar? = 4-pyridyl, Ar = 4- methoxyphenyl) gave a [(4?-methoxyphenyl)imino](4-pyridyl)acetonitrile (7).     A series of monophenylimino derivatives of 2,2?-pyridil, and some anilides of isonicotinic acid, were prepared.