Use of a mesoporous material for organic synthesis.

A common problem in synthetic organic chemistry is attaining proper contact between lipophilic organic compounds and inorganic salts. Various strategies, for example, phase transfer catalysis (Starks, C. M.; Liotta, C. L.; Halpern, M. Phase Transfer Catalysis: Fundamentals, Applications and Industrial Perspectives; Chapman & Hall: New York, 1994) or use of a microheterogeneous medium such as a microemulsion (Hager, M.; Currie, F.; Holmberg, K. Organic Reactions in Microemulsions. In Colloid Chemistry II; Antonietti, M., Ed.; Topics in Current Chemistry 227; Springer-Verlag: Heidelberg, 2003; p 53) have been worked out to tackle the issue. Here, we report that mesoporous solid materials made from surfactant self-assembly can be used as medium for such reactions. The material is made from silica, and the pore size is large, relatively uniform, and can be controlled with a high degree of precision by the choice of surfactant that is being used as template (Palmqvist, A. E. C. Curr. Opin. Colloid Interface Sci. 2003, 8, 145). The pores are hydrophilic and are filled with an aqueous solution containing the inorganic salt. The porous material is dispersed in the lipophilic organic substrate, that is, 4-tert-butylbenzyl bromide, or in a hydrocarbon solution of this substrate. The reaction occurs at the hydrophilic/lipophilic interface, and, because the interface is large, the reaction is fast. A considerable advantage with this new reaction medium is that the workup procedure is extremely facile. After the reaction is completed, the solid is simply removed by filtering or centrifugation.