Karine Villeneuve

Ruthenium-Catalyzed Asymmetric [2 + 2] Cycloadditions between Chiral Acyl Camphorsultam-Substituted Alkynes and Bicyclic Alkenes

Ruthenium-catalyzed asymmetric [2 + 2] cycloadditions between chiral acyl camphorsultam-functionalized alkynes and bicyclic alkenes were examined, providing adducts with complete exo stereoselectivity in good overall yield and enantioselectivity (up to 99% and 166:1, respectively), as well as appreciable diastereoselectivity (up to 163:1). The diastereoselectivity showed dependence on the solvent and temperature, as well as on the substitution pattern of the reacting alkyne and bicyclic alkene components. In general, higher diastereoselectivities were observed for reactions conducted in ethereal solvents and at lower temperatures between N-propynoyl camphorsultams and bicyclic alkenes.

5,6-[2α-Acetyl-1β-(ethoxy­carbonyl)­ethyl­idene]-1,3,3a,4,5,6,7,7a-octa­hydro-4,7-epoxy­isobenzo­furan-1,3-dione

The regio- and relative stereochemistry of the title compound, C15H16O7, has been established by X-ray analysis. The molecular dimensions are normal. Molecules form centrosymmetric hydrogen-bonded dimers through two independent weak C—H⋯O interactions.