Base‐Promoted Synthesis of 3‐Alkenyl‐2‐pyridones from N‐Propargyl‐β‐enaminones and Aryl Aldehydes

Main observation and conclusion In this article, we report a base‐promoted sequential cyclization/aldol‐type condensation/isomerization cascade reaction of N ‐propargyl‐β‐enaminones with aryl aldehydes. The key step in this protocol is the generation of 1,4‐oxazepine anions from N ‐propargyl‐β‐enaminones under basic conditions, which are captured by aryl aldehydes. The method allows the formation of one pyridone core and one C—C double bond in “one pot”, and the preparation of a variety of densely decorated pyridone derivatives in moderate to good yields with broad functional group tolerance.