Synthetic Studies on Fungicidal Agent. VII. Reaction of 2-Picoline and Aromatic Primary Amines (or Aromatic Nitro Compounds) in the Presence of Sulfur.

Abstract

The condensation of 2-picoline with various aromatic primary amines (or nitro compounds) in the presence of sulfur was carried out at elevated temperature. This reaction was tentatively divided into three types : The first type is a simple thiopicolinoyl ; the second, a mixed type, yielding thiopicolinoyl and thiazolyl cyclization products ; and the last, unchanged (or resinous). It is noteworthy that protomeric amino group, such as that of N1-position of sulfanilamide and 2-position of pyridine, was active to some extent for this reaction. Oxidative cyclization of five thiopicolinoyl intermediates (XXI, XXIII, and XXIV) from dianisidine, sulfanilamide, homosulfanilamide, 2-aminopyridine, and 5-nitro-2-aminopyridine with potassium ferricyanide was unsuccessful, but not for (XXII) and (XXV). The chemical structure of these cyclization products was discussed on the basis of their ultraviolet spectral observation and electronic theory. Microbiological activity of these compounds will be reported elsewhere.