Reversing the Stereoselectivity of a Palladium‐Catalyzed O‐Glycosylation through an Inner‐Sphere or Outer‐Sphere Pathway

An efficient and concise method for the construction of various O‐glycosidic bonds by a palladium‐catalyzed reaction with a 3‐O‐picoloyl glucal has been developed. The stereochemistry of the anomeric center derives from either an inner‐sphere or outer‐sphere pathway. Harder nucleophiles, such as aliphatic alcohols and sodium phenoxides give β‐products, and α products result from using softer nucleophiles, such as phenol.