High Yield Synthesis of Filicinic Acid, Based on the Polychlorination of 4,4-Dimethyl-2-Cyclohexenone Part II: Conversion of 2,3,5,6-tetrachloro-4,4-dimethyl-2,5-cyclohexadienone into filicinic acid and related cyclohexadienones

✍ Scribed by L. De Buyck; N. De Kimpe; R. Verhé; N. Schamp

• Publisher: Wiley (John Wiley & Sons)
• Year: 2010
• Weight: 309 KB
• Volume: 92
• Category: Article
• ISSN: 0037-9646
• DOI: 10.1002/bscb.19830920307

✦ Synopsis

Abstract

Filicinic acid (5) was prepared in 75‐80% overall yield from 4,4‐dimethyl‐2‐cyclohexenone (1). The key intermediate, tetrachlorodienone 2, underwent facile substitution of both β‐chlorine substituents by methoxide affording the bis enol ether 3 which was converted into dichlorofilicinic acid 4 in hot 85% sulfuric acid. Monohydroxy derivatives were obtained by treatment of 2 or 3 with hydroxide. Palladium‐catalysed low‐pressure hydrogenation of 4 under appropriate conditions produced monochlorofilicinic acid, filicinic acid or 5‐hydroxy‐4,4‐dimethyl‐1,3‐cyclohexanedione (8) with high selectivity.