Synthesis of alpha-hydroxy and alpha-oxospiranes through ruthenium(II)-catalyzed ring-closing metathesis

Efficient methodology for the construction of functionalized spiranes using Ru(II)-catalyzed ring-closing metathesis reactions is described. The subst rates were appropriately substituted five-, six- and seven-membered cycloal kanes which were spiroannulated by five-, six- and seven-membered rings, re spectively. The relative stereochemistry of selected substituted spiranes h as been determined by single crystal X-ray analyses. The X-ray structures f ormed the basis for NMR correlations of the relative stereochemistry in the groups of compounds prepared. Relative rates in oxidation reactions could also be used for stereochemical correlations.