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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.