Reactions of 2,2,6‐Trimethyl‐1,3‐dioxin‐4‐one with the Aryl Aldimines Prepared from Thiophene‐2‐carbaldehyde

The reactions of aryl aldimines derived from thiophene‐2‐carbaldehyde ( 5–9 ) with 2,2,6‐trimethyl‐1,3‐dioxin‐4‐one (1) were investigated. The new 1,3‐oxazin‐4‐ones and thienylidene acetoacetamides were obtained in good yields. The synthetic utility of the latter via an intramolecular tandem Friedel–Crafts alkylation–acylation to give tetracyclic heterocyclic rings was also explored.