The Chemical Synthesis of the 1-C-Alkyl Substituted Pyrrolidine and Piperidine Iminosugar Natural Products and their Analogues

A review of the chemical synthesis of the 1-C-alkyl substituted pyrrolidine and piperidine iminosugar natural products and their analogues (where the alkyl chain comprises two or more car-bons) is provided. These syntheses can be grouped into nine different synthetic strategies that share a common approach toward installing the alkyl substituent. These include nucleophilic addition to al-dimines; Grignard additions to glycosylamines, cyclic imides, and carbohydrates; Weinreb ketone synthesis; nucleophilic addition to cyclic nitrones; the Overmann rearrangement; the allylation of hemiaminals; and the Petasis borono-Mannich reaction. The broussonetine alkaloids have proven popular synthetic targets to develop new synthetic methods and verify these target molecules' struc-tures and stereochemistry.