Diastereoselective syntheses of 1-deoxyhomonojirimycin and two new 1,5,6-trideoxy-1,5-iminoheptitols with d-allo- and l-talo-configuration
文摘
The synthesis of 1-deoxyhomonojirimycin 2, as well as two new diastereomers, namely 1,5,6-trideoxy-1,5-imino-d-allo-heptitol 3 and 1,5,6-trideoxy-1,5-imino-l-talo-heptitol 4, is described. Compound 2 was obtained from 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose—while 3 and 4 were obtained from 1,2:5,6-di-O-isopropylidene-α-d-allofuranose. These compounds were transformed in a few steps to the corresponding β-ketoesters 12 and 18, respectively, which were hydrogenated diastereoselectively in the presence of chiral ruthenium complexes with total control of the C-5 stereogenic centre. The resulting β-hydroxyesters 13, 19a and 19b are key intermediates for the syntheses of the 1,5,6-trideoxy-1,5-iminoheptitols 2, 3 and 4, respectively.