Asymmetric Organocatalytic Relay Cascade Michael/Michael/Henry Reaction Sequence: Control Of All Stereocenters In One Cyclohexane Skeleton

Organocatalytic enantioselective construction of complex molecules with multiple chiral centres via a cascade reaction is one of the rapidly growing frontier fields. Cascade reactions avoid time-consuming and costly protection/deprotection processes as well as the purification of intermediates and generate several bonds in a one-pot fashion. Cascade reactions have circumvented many synthetic problems since it developed so far. However, current research in the field has great limitations:the designing of the most cascade reactions are based on the combination of enamine and iminium activation as well as hydrogen bonding catalysis; current reactions are most two-step sequence, so the development of three or more step reactions is necessary; many significant moleculars are difficult to construct by relying on the employment of a single chiral catalyst.Cascade reactions are a powerful tool in organic synthesis that allows the construction of cyclic compounds with multiple stereocenters in one-pot procedures. However, synthesis of hexasubstituted cyclohexanes with control of all six stereocenters by asymmetric tandem or cascade reaction still remain a challenge. We developed a relay cascade Michael/Michael/Henry reaction between aliphatic aldehydes and nitroalkenes catalyzed by combination of two different organocatalysts to generate hexasubstituted cyclohexanes. This thesis includes the following two parts:1. We discuss the important development of organocatalytic cascade reactions over the past few years. This section mainly contains the efficient and stereoselective construction of cyclic compounds which exist in pharmaceutical compounds and complex natural products.2. We developed a asymmetric organocatalytic relay cascade Michael/Michael/Henry reaction. The reaction comprises an aliphatic aldehyde, a nitroalkenes, a readily available diphenylprolinol silyl ether and the quinine thiourea. The corresponding adducts are afforded in good yields, moderate to high diastereoselectivities, and excellent enantioselectivities.