Synthetic Approach toN-Alkylated 2,5-Diamino-2,5-dideoxy-1,4;3,6- dianhydroalditols by Reductive Alkylation

Abstract

N,N'-Dialkylated 2,5-diamino-2,5-dideoxy-1,4;3,6-dianhydroalditols, representing interesting basic catalysts for polyaddition reactions, are synthesized by different reductive alkylation procedures in satisfactory yields. D-Gluco- and L-ido-N,N'-dialkyl-2,5-diamino-2,5-dideoxy-1,4;3,6-dianhydroalditols 7-8, 10-15 are accessible by reaction of the corresponding diamines with carbonyl compounds and reduction of the intermediately formed imine. For the synthesis of D-manno-N,N'-dialkylated diamines, an alternative route via 1,4;3,6-dianhydro-D-threo-2,5-hexodiulose (18) is established, thus avoiding the six-step synthesis towards 1,4;3,6-dianhydro-D-mannitol (2). Reductive alkylation of diketone 18 yields stereospecifically only the alkylated diamine 21 with D-manno-configuration. In case of the monoketones only 1,4:3,6-dianhydro-L-sorbose (16) can be transformed stereospecifically to N-2-pentyl-5-amino-5-deoxy-1,4:3,6-dianhydro-D-sorbitol (19), whereas 1,4:3,6-dianhydro-D-fructose (17) yields a mixture of D-manno- and D-gluco-monoamines 20a and 20b by reductive alkylation with 2-pentylamine and sodium borohydride