Chiral thiourea derivatives as organocatalyts in the enantioselective Morita- Baylis-Hillman reactions

Abstract

Novel chiral bifunctional thiourea derivatives have been synthesised and successfully applied to the intermolecular Morita-Baylis-Hillman (MBH) reaction of an aromatic aldehyde with methyl vinyl ketone (MVK) and to the intramolecular MBH reaction of ω-formyl-enone. The corresponding products were obtained with high enantioselectivities (up to 98% ee). The thiourea organocatalyst derived from a β-amino alcohol gave high enantioselectivities (92% ee) in the intermolecular MBH reaction, whereas the same chiral ligand afforded the corresponding product in high yield (85%) with moderate enantioselectivity (75% ee) in the intramolecular MBH reaction. The use of a thiophene ring-containing thiourea derivative gave high enantioselectivities in the intermolecular and intramolecular MBH reactions (85% and 95% ee, respectively).