Asymmetric Allylic Alkylation (AAA) Reactions

In recent years, organocatalysis have received great attention in asymmetric synthesis for itsenzyme mimic, metal-free, atomatically economic and low toxic characters. Organocatalyticreactions are becoming powerful tools in the construction of complex molecular skeletons.Recently, the metal-free organic Lewis base-catalysed allylic alkylation of Morita–Baylis–Hillman(MBH) adducts has emerged as a powerful strategy to produce multifunctional allylic-substitutedcompounds, in which exclusive regioselectivity has been generally noted. In this thesis, weexamined the catalytic activities of cinchona alkaloid derivatives in asymmetric allylichydroxylation, asymmetric allyic-allylic alkylation and asymmetric aldol reaction. Thisdissertation mainly focuses on3aspects as follows:1Lewis Base-Catalyzed Enantioselective Allylic Hydroxylation of Morita-Baylis-HillmanCarbonates with WaterA Lewis base-catalyzed allylic hydroxylation of Morita-Baylis-Hillman (MBH) carbonateshas been developed. Various chiral MBH alcohols can be synthesized in high yields (up to99%)and excellent enantioselectivities (up to94%ee). This is the first report using water as nucleophilein asymmetric organocatalysis. The nucleophilic role of water has been verified using¹⁸O-labelling experiments using the computational confirmed mechanism.2Asymmetric Allyic-Allylic Alkylation of β, γ-Unsaturated Ketones and Morita-Baylis-Hillman cabonates A cinchona alkaloids catalyzed allylic alkylation of Morita-Baylis-Hillman (MBH)carbonates and β,γ-unsaturated ketones has been developed. Various chiral hexa-1,5-dienesproducts can be synthesized in moderate yields (up to82%) and excellent enantioselectivities (upto94%ee) and excellent steroselectivity (up to99:1). Cyclohexene of high enantioselective weresynthesized.3Enantioselective Organocatalytic Vinylogous Aldol Reaction of Allyl Ketones toIsatinesThe amino acids thiourea derivatives catalysed asymmetric Aldol reaction of β,γ-unsaturatedketones with Isatines is reported. Various chiral allylic hydroxylation products can be synthesizedin high yields (up to95%), excellent enantioselectivities (up to99%ee) and excellentstereoselectivity (up to99:1).