Fluorinated analogues of nojirimycin and mannojirimycin from a non-carbohydrate precursor

1,3,5-Trideoxy-3-fluoronojirimycin 3a and its 5-epi isomer 3b have been synthesized in enantiomerically pure form starting from the fluorohydroxysulfinylhexene (2R,3S,S-S)-6. The nitrogen atom of the target bioactive compounds is introduced by replacing the sulfinyl group with an hydroxylamine residue and an intramolecular aminomercuration reaction builds up the desired piperidine ring. Finally, an oxidative demercuration affords the hydroxymethyl moiety. The same synthetic sequence allows to obtain 1,3,5-trideoxy-3-fluoromannojirimycin 4a and its 5-epi isomer 4b starting from the benzyloxy-fluorosulfinylhexene (2S,3S,R(S))-7.