Rapid C–S Coupling in Water via Ion-Pair-Catalyzed Dehydration

The C-S bond is of significant importance due to its unique properties and diverse roles in chemistry, biology, and materials science. In this work, we present an efficient synthetic protocol of a rapidly dehydrative C-S coupling reaction with alcohols and thiols in water catalyzed by a triaryl-carbenium ion pair. Under metal-free conditions, a wide range of thioethers were obtained in good yields (up to 99%) with excellent functional group tolerance, including the fast modification of amino acid derivatives and functional molecules. This method allowed reactions to be conducted with low catalyst loading, down to 1.0 mol %, and was practical for gram-scale synthesis. Furthermore, the reactions were performed under biocompatible conditions, making this approach highly suitable for potential bioconjugation.