title: Asymmetric organocatalytic thio-Diels-Alder reactions via trienamine catalysis.
abstract: We report a new process to access highly enantioenriched sulfur-based heterocycles by an asymmetric catalytic thio-Diels-Alder reaction. Thiocarbonyls are challenging heterodienophiles in enantioselective Diels-Alder reactions, due to their inherent high reactivity and their poor ability to coordinate to chiral catalysts. We successfully circumvented these problems by employing a different strategy, which explores the use of in situ generated catalyst-bound dienes. Synthetically useful dihydrothiopyrans as well as other bi- and tricyclic sulfur-containing heterocycles are formed in high yields and high to excellent selectivities. DFT calculations were performed to examine the mechanism of the developed reaction. Furthermore, a series of synthetic transformations of the optically active sulfur-based heterocycles are presented.
authors.affiliation: Center for Catalysis, Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark.
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: David Cruz
authors.initials: DC
authors.lastname: Cruz
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Vibeke Henriette
authors.initials: VH
authors.lastname: Lauridsen
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen