Ferrier rearrangement promoted by an electrochemically generated zirconium catalyst

• A new method for the preparation of 2,3-unsaturated thioglucosides from glycals.
• Zirconium catalyzed Ferrier rearrangement in the presence of S- and C-nucleophiles.
• Electrochemical generation of the catalyst from a sacrificial zirconium anode.
• Moderate stereoselectivity of the reaction (α/β anomer ratio was 3.00–15.67).
• The protocol requires no complex and expensive equipment.

In situ generated zirconium catalyst from a sacrificial zirconium anode was successfully applied to promote Ferrier rearrangement of 3,4,5-tri-O-acetyl-d-glucal and 6-deoxy-3,4-di-O-acetyl-l-glucal (3,4-di-O-acetyl-l-rhamnal) in the presence of three thiols and eleven thiophenols as nucleophiles. A simple constant current electrolysis (20 mA, 0.4 F mol−1) of an acetonitrile solution of lithium perchlorate (0.1 M) containing the corresponding glycal and S-nucleophiles, using a zirconium anode and a platinum cathode resulted in the successful synthesis of the corresponding 2,3-unsaturated peracetylated thioglycosides (with an average anomer ratio α/β=4.129 in the case of peracetylated d-glucal and 8.740 in the case of l-rhamnal). The same procedure proved to be appropriate in synthesizing dihydropyran derivatives (‘C-glycosides’) using allyltrimethylsilane as the nucleophile (only ‘α-anomers’ were obtained). All new compounds were fully characterized by spectral data, whereas single-crystal X-ray analysis was performed for two thioglycosides.

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