α- and β-anomers with galacto- and gluco-configuration, respectively. Nitro group reduction to the amino group and also ester cleavage led to compounds 2, 6, and 11, which can be regarded as dipeptide mimetics. From these compounds, bicyclic pyrano[2.3-b][1,5]oxazepines 7–14 were prepared by ring closure.
N-Boc 保护的
丝氨酸和苏
氨酸酯可以很容易地添加到 2-硝基糖中,分别提供具有半
乳糖和
葡萄糖构型的 α- 和 β-端基异构体。硝基还原为
氨基以及酯裂解产生化合物 2、6 和 11,它们可以被视为二
肽模拟物。从这些化合物中,通过闭环制备双环
吡喃并 [2.3-b] [1.5] 氧氮杂 7-14。