CHEMISTRY OF PYRIDINE .6. STERIC AND ELECTRONIC EFFECTS INFLUENCING DEOXYDATIVE SUBSTITUTION OF PYRIDINE N-OXIDES BY MERCAPTANS IN ACETIC ANHYDRIDE

The deoxydative substitution of N-oxides derived from pyridine, 2-, 3-, and 4-picoline, 4-t-butylpyridine, 4-phenylpyridine, and 2,6-, 3,4-, and 3,5-lutidine by t-butyl mercaptan in acetic anhydride is reported. It was found that ring substitution introduced a t-butyl sulfide group at any one of the available a positions (2,6-lutidine 1-oxide being the exception) and only at those β positions which had originally a free α position adjacent to it. Mechanisms to explain both α and β substitution via 1-acetoxy-2-t-butylmercapto-1,2-dihydropyridines are postulated. Evidence is presented that β substitution involves migration of the sulfide function from such 1,2-dihydropyridines via episulfonium intermediates. © 1969, American Chemical Society. All rights reserved.