Electrophilic Difluoro(phenylthio)methylation: Generation, Stability, and Reactivity of α‑Fluorocarbocations

Electrophilic difluoro(phenylthio)methylation of allylsilanes has been achieved using bromodifluoro(phenylthio)methane (PhSCF₂Br) and silver hexafluoroantimonate (AgSbF₆). The structural assignment and observation of α-fluorocarbocation were substantiated by NMR and theoretical calculations. Detailed mechanistic and electronic studies have provided a fundamental understanding of the reactivity and stability of the difluoro(phenylthio)methylium cation (PhSCF₂⁺)

Asymmetric Total Syntheses of Megacerotonic Acid and Shimobashiric Acid A

The asymmetric total syntheses of the α-benzylidene-γ-butyrolactone natural products megacerotonic acid and shimobashiric acid A have been accomplished in nine and 11 steps, respectively, from simple, commercially available starting materials. The key step for each synthesis is the (arene)RuCl(monosulfonamide)-catalyzed dynamic kinetic resolution-asymmetric transfer hydrogenation (DKR-ATH) of racemic α,δ-diketo-β-aryl esters to establish the absolute stereochemistry. Intramolecular diastereoselective Dieckmann cyclization forms the lactone core, and ketone reduction/alcohol elimination installs the α-arylidene. [Image: see text