10.1021/ol202582c
The study presents an efficient method for the N-alkylation of sulfonamides and amines using alcohols as alkylating reagents, catalyzed by manganese dioxide (MnO2) under aerobic and solvent-free conditions. This approach is a greener alternative to traditional methods, as it avoids the use of noble metal catalysts, preformed complexes, and inert atmosphere protection. The researchers found that MnO2 is a less toxic, readily available, and recyclable catalyst that can facilitate the reaction at mild temperatures without the need for high pressure or large excess amounts of reagents. The method was successfully applied to a variety of sulfonamides and amines, yielding good to high product yields. Additionally, the study explores the potential mechanism of the reaction, suggesting a process involving Mn-mediated alcohol oxidation, condensation, transfer hydrogenation, and regeneration of the aldehyde, which completes the catalytic cycle. The developed method simplifies operation and workup procedures and may serve as a promising alternative to existing N-alkylation methods.
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