Synthesis of α-pyrones from α-oxo ketene dithioacetals

✍ Scribed by R.Karl Dieter; Jeffrey R. Fishpaugh

• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 235 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)83889-7

✦ Synopsis

a-Ox0 ketene dithioacetals can be converted into a-pyrones in a three step process involving 1,2-nucleophilic addition of ester or ketone enolate anions, acid promoted rearrangement, and subsequent en01 lactonization. Utilization of ester enolates affords 6-alkylthio a-pyrones while ketone enolates give 3-alkyl substituted a-pyrones.

We recently described a synthesis of a-pyronesl from vinylogous thiol esters2 which in turn were readily prepared3 from a-oxo ketene dithioaceta1s.l