1958 年 78 巻 4 号 p. 417-421
In an earlier work of this series, numerous arylthio derivatives of 3-amino-6-chloro (methoxy, ethoxy) pyridine-2-thiol and 3-aminopyridine-4-thiol were synthesized and conditions for Smiles rearrangement to take place were examined. As a result, it was observed that these compounds were more liable to undergo rearrangement than corresponding benzene derivatives and that the rearrangement took place most easily in 3-amino-6-chloropyridine-2-thiol derivaties. This was explained as the promotion of the rearrangement by the additive effect of +I effect of the chlorine atom and +E effect of the ring nitrogen. In the present series of work experimental examinations were made on the promotion of the rearrangement by a halogen atom by preparing 3-amino-5-chloropyridine-2-thiol and 3-amino-5-bromopyridine-4-thiol and submitting them to Smiles rearrangement. As anticipated, halogen atom was found to effect promotion of the rearrangement irrespective of the position of halogen relative to the amino group or sulfur atom.