Persistent guaiazulene arylmethylium ions as electrophilic traps for metal enolates

Chem Commun (Camb). 2024 Mar 19;60(24):3339-3342. doi: 10.1039/d4cc00208c.

Abstract

Guaiazulene-stabilized cations reacted with metal enolates affording carbonyl compounds with an azulene moiety. Metal enolates generated by asymmetric conjugate addition of organometallic reagents led to enantioenriched products. Additionally, guaiazulene-substituted cations efficiently react with silyl enol ethers. DFT calculations allowed estimation of the electrophilicities of the carbocations. Reaction progress was monitored by a decrease in the reactant's Vis-light absorption and an increase in the product's anti-Kasha emission.