Synthesis of Cyclobutanated Butyrolactones via Copper(I)-Catalyzed Intermolecular Photocycloadditions of Homoallyl Vinyl or Diallyl Ethers

Article abstract of DOI:10.1021/jo00377a015

Intramolecular copper(I)-catalyzed 2? + 2? photocycloaddition provides an effective route for the synthesis of 2-oxa- and 3-oxabicyclo<3.2.0>heptanes from homoallyl vinyl or diallyl ethers, respectively.Ruthenium-catalyzed oxidation of these multicyclic tetrahydrofuran products provides a novel annulation of cyclobutanated butyrolactones.For intermediates incorporating both methine and methylene groups next to the tetrahydrofuran oxygen, a remarkable selectivity was found for oxidation at the methylene position.Highly stereoselective generation of exo-2-alkylsubstituted 3-oxabicyclo<3.2.0>heptanes occurred upon photobicyclization of diallyl ethers bearing an α-alkyl substituent.