title: Synthesis and Reactivity of Optically Active Spiroketals by Ring-Expansion of Chromium Carbene Complex-Derived Cyclobutanones.
abstract: Photolysis of cyclic chromium alkoxycarbene complexes with an optically active ene-carbamate gave spirofused, optically active cyclobutanones. Baeyer-Villiger ring expansion followed by further functionalization gave optically active spiroketals. Photochemical ring expansion of these spirofused cyclobutanones in the presence of acetic acid or thiophenol gave 2-acetoxy- or 2-(thiophenoxy)-4-spirofused tetrahydrofurans. Elimination of the thiophenoxy group gave a 3,4-dihydrofuran that underwent Heck arylation and photochemical cycloaddition with chromium carbene complexes to give cyclobutanones.
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523.
authors.forename: Ana B.
authors.initials: AB
authors.lastname: Bueno
authors.forename: Louis S.
authors.initials: LS
authors.lastname: Hegedus