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 predominantly Z-configuration. The reaction likely occurs via alkyne-carbonyl metathesis of a hydroxy-ynol ether intermediate, acid-promoted alkene E- to Z-isomerization, and lactonization.

SUBMITTER: Ng K 

PROVIDER: S-EPMC4698893 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature