Steric control in Pd-mediated cycloisomerization of sugar alkynols: documentation of a rare allylic epimerization

Pd-mediated cycloisomerization of C3-alkynylated glucofuranosyl derivatives revealed a dominance of steric factors over electronic factors. However, the intermediate glycals were epimerized prior to the ketalization and afforded the more stable cis-fused bicyclic ketals.