Nontraditional Synthesis\nof Disaccharides via Acyclic\nVinylic Ether Intermediates: Catalytic C–O Cross-Coupling as\nthe Enabling Link

We describe complementary methods for synthesizing acyclic\nvinylic\nethers from two carbohydrate-derived synthons. We compare a nonstereoselective\nolefination approach with a stereoselective catalytic C–O cross-coupling\nmethod, preparing 1,2-disubstituted vinylic ethers with complexity\non both sides of the ether linkage. Upon epoxidation/<i>in situ</i> oxacyclization of acyclic vinylic ethers, we synthesized disaccharides\nwith α-d-galacto-, α-d-talo-, β-d-allo-, and α-d-altropyranoside stereochemistry,\nfrom d-lyxose and d-ribose precursors. Stereoselective\nCuI/CyDMEDA-catalyzed C–O cross-couplings offer considerable\npotential for broadly implementing this nontraditional strategy for\nglycoside synthesis.