Synthesis of (1R,4R)-2,5-diazabicyclo[2.2.1]heptane derivatives by an epimerization–lactamization cascade reaction
作者:Benqiang Cui、Jie Yu、Fu-Chao Yu、Ya-Min Li、Kwen-Jen Chang、Yuehai Shen
DOI:10.1039/c4ra13611j
日期:——
An epimerization–lactamization cascade of functionalized (2S,4R)-4-aminoproline methyl esters is developed and applied in synthesizing (1R,4R)-2,5-diazabicyclo[2.2.1]heptane (DBH) derivatives. (2S,4R)-4-Aminoproline methyl esters are likely to undergo 2-epimerization under basic conditions, followed by an intramolecular aminolysis of the (2R)-epimer to form the bridged lactam intermediates. Key factors
开发了功能化的(2 S,4 R)-4-氨基脯氨酸甲酯的差向异构-内酰胺化级联,并将其应用于合成(1 R,4 R)-2,5-二氮杂双环[2.2.1]庚烷(DBH)衍生物。(2 S,4 R)-4-氨基脯氨酸甲酯很可能在碱性条件下发生2-异构化,然后(2 R)-异构体的分子内氨解反应形成桥连的内酰胺中间体。确定用于该级联反应的关键因素包括底物中的吸电子N保护基和作为促进剂的强碱。