Manganese(I)-Pincer Catalyzed ?-Alkylation of Sulfones by Alcohols

Sulfones are building blocks in organic synthesis and pharmaceutical chemistry. Direct alpha-alkylation of sulfones using alcohols with water as the sole byproduct is an efficient and promising method for their structural modifications. However, competitive reactions always exist in this transformation that influences the reaction selectivity. For example, in addition to the desired alpha-alkylation, Julia-type olefination and alpha-alkenylation are frequently observed, especially when benzyl alcohol derivatives were used as alkylation reagents. Herein, we report alpha-alkylation of sulfones using alcohols catalyzed by a pincer complex of earth-abundant manganese. The Mn-PNN-bipyridyl complex exhibited good performance in reaction selectivity. The amount of base also had an important influence on the smooth transformation. Aromatic and aliphatic alcohols are suitable alkylation reagents for sulfones at low metal catalyst loading (0.5 mol %), highlighting the practicality of the developed system.