The exocyclic olefin, 5, obtained from the known epoxy uloside, methyl 2,3-anhydro-β-D-erythro-pentopyranosid-4-ulose, 3, reacts with ammonia or methylamine to give the 3-amino-3-deoxy or 3-methylamino-3-deoxy derivatives respectively. The benzamide, 8c, obtained from the former, reacts with iodonium ion to give an oxazoline in which the cis relationship between the tertiary alcohol and the 3-amino group of garosamine is secured. Deiodination is followed by a one-pot N-methylation and reduction. A hydrolysis gives methyl α-L-garosamimide 2. In a second route, the urethane, 16c, reacts with iodonium ion to give an oxazolidone 17a. This reaction establishes the N-hydroxyamino moiety and circumvents the N-methylation/reduction steps. Deiodination followed by deprotection yields methyl α-L-garosaminide 2. Both routes require eight steps from 3 with overall yields of 14% and 11%, respectively.
从已知的环氧乌洛糖苷,甲基2,3-脱水-β-D-赤脂-戊聚糖-4-乌洛糖获得的外环烯烃5,分别与氨或甲胺反应,得到3-氨基-3-脱氧或3-甲基氨基-3-脱氧衍生物。从前者获得的苯甲酰胺8c,与碘离子反应,形成一种噁唑啉,其中保证了三级醇和加罗沙胺的3-氨基团之间的顺式关系。脱碘后进行一锅式N-甲基化和还原。水解得到甲基α-L-加罗沙胺酰胺2。在第二条路线中,尿素酯16c与碘离子反应,形成一种噁唑酮17a。该反应建立了N-羟基氨基团,避开了N-甲基化/还原步骤。脱碘后去保护得到甲基α-L-加罗沙胺苷2。这两种途径从3经过八个步骤,总产率分别为14%和11%。