Reaction of 1,4-anhydro-2,3,5-tri-O-benzyl-1-deoxy-1-imino-D-arabinitol N-oxide (8) with allyl alcohol produced a 3.6:1 mixture of the two pyrrolo[1,2-b]isoxazole derivatives 13 and 14. The major adduct 13 was converted to 7-deoxycasuarine (7), a potent, specific, and competitive inhibitor of amyloglucosidase from Rhizopus mold (see Table).