Synthesis of potent alpha-D-mannosidase and alpha-L-fucosidase inhibitors:4-amino-4-deoxy-D-erythrose and 4-amino-4,5-dideoxy-L-lyxose

Amino-sugars 3a,b, analogues of L-fucose, and their sulfite adducts 11a,b w ere synthesised via asymmetric hetero Diels-Alder reaction and, for 3b, 11b , via methyl isomerisation of the intermediary oxazane-diol 7b. 4-Amino-D-e rythrose sulfite adduct 11a is a potent a-D-mannosidase inhibitor, L-lyxose derivatives 3b, 11b are very active as a-L-fucosidase inhibitors.