Organocatalytic Enantioselective Functionalization of Cyclic α-Hydroxyamides: Access to Chiral Cyclic Imides and Azapolycyclic Compounds.

A highly efficient enantioselective enamine-catalyzed asymmetric conjugate addition has been developed to directly convert unfunctionalized cyclic α-hydroxyamides into chiral cyclic α-hydroxyamides by reacting with vinyl sulfones, which could be used as versatile azacyclic synthons in the following sequences: (1) as the precursors of cyclic N-acyliminium ions to prepare natural productlike chiral azapolycyclic compounds under acidic conditions and (2) to construct chiral cyclic imides bearing unilateral substituents via oxidation reaction-induced formal desymmetrization.

Brønsted-Acid-Catalyzed In Situ Formation of Acyclic Tertiary Enamides and Its Application to the Preparation of Diverse Nitrogen-Containing Heterocyclic Compounds.

A Brønsted acid-catalyzed cascade process, involving in situ formation of acyclic tertiary enamides and intramolecular Michael reaction, is developed for the synthesis of functionalized cyclic tertiary enamides. Based on the dual reactivities of the enamide moiety, several reaction sequences were realized by using rationally designed substrates, leading to biologically relevant nitrogen-containing heterocyclic compounds with diverse structural skeletons in a concise and diastereocontrolled manner.