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

J Org Chem. 2014 Nov 21;79(22):10908-15. doi: 10.1021/jo501913z. Epub 2014 Oct 31.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Naphthylamine / analogs & derivatives*
  • 1-Naphthylamine / chemical synthesis
  • 1-Naphthylamine / chemistry
  • Carbon / chemistry
  • Cobalt / chemistry
  • Crystallization
  • Magnetic Phenomena
  • Metal Nanoparticles / chemistry*
  • Protons
  • Recycling

Substances

  • Protons
  • Cobalt
  • 1,8-bis(dimethylamino)naphthalene
  • Carbon
  • 1-Naphthylamine