Tandem Nucleophilic Addition/Cyclization Reaction in the Synthesis of Ketimine-Type Iminosugars

The biological activity of unsaturated iminosugars has not yet been extensively studied because of a lack of general synthetic methods. A practical synthesis of these cyclic ketimine sugars was developed, which was based on a tandem addition−cyclization reaction of a Grignard reagent to a ω-methanesulfonylglycononitrile.