title: Enantioselective all-carbon (4+2) annulation by N-heterocyclic carbene catalysis.
abstract: The enantioselective vinylogous Michael/aldol cascade is an underdeveloped approach to cyclohexenes. Herein we describe a highly enantioselective (most ≥ 98:2 er) and diastereoselective (all ≥ 15:1 dr) N-heterocyclic carbene catalyzed cycloisomerization of acyclic dienyl esters to cyclohexyl β-lactones. Derivatizations avail cyclohexenes bearing four contiguous stereogenic centers, while mechanistic studies support olefin isomerization prior to cyclization.
authors.affiliation: School of Chemistry, Monash University , Clayton 3800, Victoria, Australia.
authors.forename: Lisa
authors.initials: L
authors.lastname: Candish
authors.forename: Alison
authors.initials: A
authors.lastname: Levens
authors.forename: David W
authors.initials: DW
authors.lastname: Lupton
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D053138:Cyclohexenes / Q000138:chemical synthesis* / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D053138:Cyclohexenes; D006571:Heterocyclic Compounds; C030011:carbene; D002244:Carbon; D008697:Methane