Reaction of 1,3-Oxazinium Salt with Active Methylene Compounds

Abstract

Abstract 2,4,6-Triphenyl-1,3-oxazinium perchlorate reacts with active methylene compounds to give several butadiene derivatives and various pyridine derivatives. The reactions seem to proceed as follows: The carbanion from an active methylene compound attacks the 6-position of the oxazinium ring, and opens the ring to form a butadiene as an intermediate, which is then recyclized to a pyridine derivative according to a characteristic mode. The mode of recyclization differs with the constituent of each active methylene. There are five modes characteristic of cyano-, ester-, amido- and benzoyl constituents and nitromethane. A compound containing two different constituents usually follows either of the two possible modes.