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Magnetic Superbasic Proton Sponges Are Readily Removed and Permit Direct Product Isolation
- Schneider, Elia M., Raso, Renzo A., Hofer, Corinne J., Zeltner, Martin, Stettler, Robert
D., Hess, Samuel C., Grass, Robert N., Stark, Wendelin J.
- Journal of organic chemistry 2014 v.79 no.22 pp. 10908-10915
- catalysts, catalytic activity, chemical bonding, chemical reactions, chemical structure, chromatography, cobalt, crystallization, magnetism, nanoparticles, naphthalene, organic chemistry, solubility
- Workup in organic synthesis can be very time-consuming, particularly when using reagents with both a solubility similar to that of the desired products and a tendency not to crystallize. In this respect, reactions involving organic bases would strongly benefit from a tremendously simplified separation process. Therefore, we synthesized a derivative of the superbasic proton sponge 1,8-bis(dimethylamino)naphthalene (DMAN) and covalently linked it to the strongest currently available nanomagnets based on carbon-coated cobalt metal nanoparticles. The immobilized magnetic superbase reagent was tested in Knoevenagel- and Claisen–Schmidt-type condensations and showed conversions of up to 99%. High yields of up to 97% isolated product could be obtained by simple recrystallization without using column chromatography. Recycling the catalyst was simple and fast with an insignificant decrease in catalytic activity.