Double Friedel–Crafts Acylation Reactions on the Same Ring of a Metallocene: Synthesis of a 2,5-Diacetylphospharuthenocene

✍ Scribed by Dr. Duncan Carmichael; Prof. Dr. Pascal Le Floch; Dr. Xavier F. Le Goff; Dr. Olivier Piechaczyk; Dr. Nicolas Seeboth

• Book ID: 102795644
• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 667 KB
• Volume: 16
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200902409

✦ Synopsis

Abstract

The synthetic outcome of the Friedel–Crafts acylation of 1′,2′,3,3′,4,4′,5′‐heptamethylphospharuthenocene reflects the nature of the acylating agent, with alkanoyl anhydride/trifluoromethanesulfonic acid (TfOH) reagents giving monosubstitution at the phospholyl ring, whereas alkanoyl chloride/AlCl~3~ gives 2,5‐disubstitution. DFT calculations indicate that this unusual double acylation can be facilitated by the intervention of the phosphorus atom at an early stage in the reaction trajectory, with the acyl group being delivered from the phosphorus atom into the ring 2‐ or 2,5‐positions.