Studies On Enantioselective Three-Component Reaction Catalyzed By Chiral Tertiary Amino-Thioureas

Two enantioselective three-component reactions catalyzed by chiral tertiary amino–thioureas have been studied.The asymmetric synthesis of 2-amino-4H-chromene derivatives with moderate to good yield via one-pot three-component reaction of salicylaldehyde, malononitrile or cyanoacetate and nitroalkane catalyzed by Takemoto catalyst has been achieved. The reaction of salicylaldehyde, malononitrile/cyanoacetate with nitromethane give high enantioselectivities. The reaction of salicylaldehyde, malononitrile/cyanoacetate with 2-nitropropane give poor enantioselectivities. The reaction of salicylaldehyde, malononitrile or cyanoacetate with nitroethane or 1-nitropropane give poor diastereoselectivities and moderate enantioselectivities. The pathway of this three-component reaction has been probed. The 2-amino-4H-chromene derivatives were obtained by the Knoevenagel condensation, intramolecular nucleophilic addition cyclization and the then following Michael reaction.The asymmetric synthesis of 2-amino-4H-pyran derivatives via one-pot three-component reaction of aromatic aldehydes, malononitrile or cyanoacetate and 1,3-dicarbonyl compounds catalyzed by chiral tertiary amino–thioureas have been studied preliminary. All the yield and enantioselectivity of this three-component reaction are moderate. The reaction conditions need to be further optimized.All the products were well characterized by 1~H NMR, (13)~C NMR, IR and HRMS. The absolute configurations of some typical products were determined by X-ray crystallographic analysis.