Enantioselective Diels-Alder Reaction of 3-Nitrocoumarins Promoted by Chiral Organoammonium Salt Catalysts

An enantioselective Diels-Alder reaction of 3-nitrocoumarins has been developed. A tryptophan-derivedC(1)-symmetric organoammonium thiourea catalyst promoted the reaction of 3-nitrocoumarins with Danishefsky's diene to give the corresponding adducts with good enantioselectivity (up to 94% ee). One of the resulting adducts was converted into a chiral carbocyclic quaternary beta-amino alcohol.