Hg(II) Reagent-Controlled Stereoselective Synthesis of 2,5-cis- and 2,5-trans-Polyhydroxylated Pyrrolidines

Abstract

Stereoselectivity in the intramolecular amidomercuration reaction of 11, which could form 2,5-cis-and 2,5-trans-polyhydroxylated pyrrolidines, was found to be dependent on the nature of the Hg(II) salts used as well as on the stereochemistry and protection state of the hydroxyl group at the allylic carbon. Thus, the amidomercuration reaction of 11 with Hg(CF 3 CO 2 ) 2 led to the predominant formation of the 2,5-cis-polyhydroxylated pyrrolidine 16, while use of Hg(CF 3 SO 3 ) 2 generated the corresponding 2,5trans isomer 17. Isomers 16 and 17 were further elaborated to stereoselectively synthesize 2,5-dideoxy 2,5-imino-D-altritol and 2,5dideoxy 2,5-imino-D-galactitol (for 20 and 21), which are known to be potent D-galactosidase inhibitors.