Solid phase synthesis of mandelic acid-derived thioethers by α-keto carbocation trapping

Resin-bound α-keto mesylates were cleaved under acidic conditions (TFA/CH2Cl2) in the presence of a variety of aryl or alkyl thiols to give the corresponding thioethers. Access to the target compounds via standard nucleophilic displacement proved to be much less efficient. The stereochemical outcome of the reaction suggested formation of a highly reactive α-keto carbocation trapped in situ by the thiol acting as a scavenger.