Highly Stereoselective Synthesis of Bis- C -ferrocenyl Glycosides via Palladium-Catalyzed Directed C-H Glycosylation.

Conjugation of carbohydrates to ferrocene scaffolds is of great value in drug design, given the nontoxic and lipophilic nature of ferrocene. However, the efficient and stereoselective synthesis of C -ferrocenyl glycosides remains a challenge. Herein, we developed a Pd-catalyzed stereoselective C-H glycosylation to provide rapid access to sole bis- C -ferrocenyl glycosides in good to high yields (up to 98% yield) with exclusive stereoselectivity. A diverse range of glycosyl chlorides were well tolerated, including d-mannose, d-glucose, l-xylose, l-rhamnose, d-mannofuranose, and d-ribofuranose. Additionally, a mononuclear Pd II intermediate was characterized by X-ray single-crystal diffraction, and might participate in the C-H palladation step.