Exploration Of Post-Ugi And Post-Passerini Transformations Towards Increased Molecular Diversity

Multicomponent reactions(MCR)and post-MCR transformations have recently emerged as efficient synthetic tools of modern organic chemistry.The substitutional progress in the field of multicomponent chemistry is associated with the rapid development and production of new materials,bioactive compounds and drugs as well as with the research on the development of new sustainable technologies.The key advantages of multicomponent protocols include broad application range and functional group tolerance,high efficiency,mild reaction conditions and operational simplicity.This thesis deals with several post-Ugi and post-Passerini transformations towards increasing the molecular diversity.The specific content is listed below.In the first part,enantioselective fluorination reaction of 2-oxo aldehyde-derived Ugi adducts promoted by Cinchona alkaloid/Selectfluor combination is described.The reaction provides a simple method for synthesizing chiral fluorine-containing post-Ugi adducts with excellent yields and good enantiomeric excesses.The stereoselectivity of the reaction can be efficiently modulated by the choice of the chiral promotor.The second part focuses on a four-component one-pot transformation involving the Passerini reaction,the Knoevenagel condensation and a transesterification providing an access to a library of densely functionalized tartaric acid derivatives.The studied transformation involves the initial reaction of a carboxylic acid,an aryl glyoxal and an isocyanide to form the Passerini adduct.This is followed by the in situ addition of ethyl glyoxalate to produce the final post-Passerini products via condensation and transesterification.The overall process can be regarded as an isocyanide-triggered benzoin-type cross-condensation of aryl glyoxal with ethyl glyoxalate.In the third part,we have studied palladium-catalyzed reductive Heck cyclizations of Ugi adducts derived from 4-bromo-lH-indole-3-carbaldehyde and 3-substituted propiolic acids for the assembly of an azepino[3,4,5-cd]indole core.In general,all steps of the strategy worked with medium to high efficiency allowing to attain a series of target products.