Magnetic Superbasic Proton
Sponges Are Readily Removed
and Permit Direct Product Isolation
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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