title: A Single-Flask Synthesis of α-Alkylidene and α-Benzylidene Lactones from Ethoxyacetylene, Epoxides/Oxetanes, and Carbonyl Compounds.
abstract: Low temperature treatment of (ethoxyethynyl)lithium with epoxides or oxetanes in the presence of BF3•OEt2, followed by addition of aldehydes or ketones and warming to room temperature, affords structurally diverse five- and six-membered α-alkylidene and α-benzylidene lactones (5) in good to excellent yields. This one-pot process, in which three new carbon-carbon bonds and a ring are formed, affords substituted α,β-unsaturated lactones of predominantlyZ-configuration. The reaction likely occursviaalkyne-carbonyl metathesis of a hydroxy-ynol ether intermediate, acid-promoted alkeneE- toZ-isomerization, and lactonization.
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Ng
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Tran
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Minehan
keywords: BF3•OEt2 promotion; Ynol ethers; tandem reactions; α-alkylidene lactones; α-benzylidene lactones