Journal of Organic Chemistry 2014-11-21

Magnetic superbasic proton sponges are readily removed and permit direct product isolation.

Elia M Schneider, Renzo A Raso, Corinne J Hofer, Martin Zeltner, Robert D Stettler, Samuel C Hess, Robert N Grass, Wendelin J Stark

Index: J. Org. Chem. 79(22) , 10908-15, (2014)

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Abstract

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.