Ionic Thiourea Organocatalysis of the Morita-Baylis-Hillman Reaction

An ionic thiourea based organocatalyst has been shown to promote a 1,4-diazabicyclo[2.2.2]octane, (DABCO) catalysed Morita-Baylis-Hillman reaction between benzaldehyde and cyclohex-2-en-1-one. The ionic thiourea catalyst was easily prepared from a pyrrolidinium salt containing an arylamine moiety and 3,5-di(trifluoromethyl)phenylisothiocyanate. X-ray crystallographic analysis of the ionic thiourea catalyst shows an acetone molecule doubly hydrogen bonded to the Lewis acidic thiourea N-H protons. Entrainment of the ionic thiourea co-catalyst in the ionic liquid N-butyl-N-methylpyrrolidinium bistriflimide, [BMPyr][N(Tf)(2)], facilitates catalyst recycling and affords very good yields with reaction times reduced through use of microwave heating.