Direct lithiation of chalcogenachromones, -flavones, and -pyranones. The interconversion and electrophilic capture of ring-opened and ring-closed anions
Cyclization of 3-(arylchalcogeno)propenoyl chlorides. 2. Chalcogen and substituent control in the regiochemistry of intramolecular acylation. Preparation of benzo[b]telluropyrones