Palladium-Catalyzed Double Allylation of Sugar-Imines by Employing Tamaru–Kimura’s Protocol: Access to Unnatural Iminosugars

Conversion of vinyl pyranosylamine and vinyl furanosylamines to 2,6- and 2,5-disubstituted pyrrolidine and piperidine iminosugars, respectively, in one pot was developed using Kimura and Tamaru’s procedure, where a Pd salt in the presence of Et₂Zn was used for the domino reaction. In this procedure, double allylation, which involves nucleophilic allylation–heterocyclization, took place to give desired nitrogen heterocycles. This strategy was further elaborated to synthesize some unnatural deoxycalystegines, hydroxylated pyrrolidines, piperidines, and indolizidine analogues