Objective

To carry out Ugi reactions as quickly and as reproducibly as possible on small scales for products that precipitate out of methanol.

Steps

  1. Weigh a 2 ml Eppendorf tube and write weight on the tube
  2. Fill with 500 microliters of methanol
  3. Add 500 micromoles of amine, aldehyde, acid and isonitrile in that order. After each addition, vortex for 15 seconds and confirm that a homogeneous solution has been obtained. If a clear solution is not obtained at any point abort.
  4. Leave tube at room temperature for 24 hours.
  5. Note the presence of a precipitate then vortex for 15 seconds.
  6. Centrifuge at x RPM for 60 seconds then discard supernatant.
  7. Add 500 microliters of methanol, vortex for 15 seconds then centrifuge at x RPM for 60 seconds.
  8. Repeat the washing procedure for a total of 3 washes.
  9. Put open tube under high vac for 15 minutes.
  10. Record weight and obtain H and C NMR of entire sample in CDCl3.
  11. Submit small sample for MS analysis.

Variations

  1. Amine and Aldehyde can be mixed and left for 3 hours before addition of acid and isonitrile to see if it makes any difference.
  2. One dram vials can be used instead of Eppendorf tubes.
  3. Use vortexing or sonication to induce precipitation.