Efficient syntheses from diacetone glucose of 1,4-dideoxy-1,4-imino-D-arabinitol, (2S,3R,4R)-3,4-dihydroxyproline, fagomine [1,5-imino-1,2,5-trideoxy-D-arabino-hexitol], and (2S,3R,4R)-3,4-dihydroxypipecolic acid by intramolecular nucleophilic displacement by an amino function of 2-O-trifluromethanesulphonates of anomeric mixtures of methyl furanosides are reported. © 1990.