Deoxyiminoalditols from Aldonolactones; I. Preparation of 1,4-Dideoxy-1,4-iminohexitols with D- and L-Allo and D- and L-Talo Configuration: Potential Glycosidase Inhibitors

Abstract

1,4-Dideoxy-1,4-iminohexitols were prepared by a convenient two-step reaction from 2,6-dibromo-2,6-dideoxyhexono-1,4-lactones by treatment with aqueous ammonia and subsequent reduction of the carboxy function with sodium borohydride. By interchange of the reactions, the dibromolactones were reduced to 2,6-dibromohexitols, which by reaction with aqueous ammonia yielded the same imino compounds. Thus, from 2,6-dibromo-2,6-dideoxy-D-mannono- (1) and -D-glucono-1,4-lactone (9) the 1,4-dideoxy-1,4-imino-L-allitol (6) and -D-talitol (14) were prepared, respectively. These two compounds were also obtained from 2,6-di-bromo-2,6-dideoxy-D-mannitol (5) and -D-glucitol (13), respectively, by reaction with aqueous ammonia. The enantiomeric 1,4-dideoxy-1,4-imino-D-allitol (18) and -L-talitol (22) were prepared similarly from the new 2,6-dibromo-2,6-dideoxy-L-mannono- (16) and -L-glucono-1,4-lactone (20), via the dibromo-L-hexitols 17 and 21, respectively. The ring closure of the dibromo compounds with ammonia has been shown to proceed via epoxides.