A novel method for the preparation of a compound of formula (I) from an N-protected-D-
mannosamine. A compound of formula (I) is a useful intermediate for the preparation of kiftnensine, a potent and selective
mannosidase inhibitor. The method includes protecting the hydroxyl group at the C-6 position of an N-protected-D-
mannosamine, to give a 6-O-protected-N-protected-D-
mannosamine; reducing the C-1 anomeric
carbon atom of the 6-O-protected-N-protected-D-mannosamine to give a 6-O-protected-N-protected-D-
mannitol; protecting the four hydroxyl groups of the 6-O-protected-N-protected-D-
mannitol; and removing the
nitrogen atom
protecting group and optionally removing the C-6
oxygen atom
protecting group to give the compound of formula (I): where R<1 >and R<2 >are each independently protecting groups which, together with the
oxygen atoms to which they are attached, form a 5-, 6-, 7- or 8-membered ring; and R<3 >is
hydrogen or a
protecting group.