Application of Cross-Conjugated Heteroaromatic Betaines to the Synthesis of the Schizozygane Alkaloid (±)-Strempeliopine
作者:Drew R. Bobeck、Hyoung Ik Lee、Andrew C. Flick、Albert Padwa
DOI:10.1021/jo901336z
日期:2009.10.2
An efficient stereocontrolled route to the isoschizozygane alkaloid core has been developed utilizing an intramolecular 1,4-dipolar cycloaddition of a cross-conjugated heteroaromatic betaine. The resulting cycloadduct undergoes loss of COS, and further reduction delivers a 5a-azaacenaphthylene intermediate that was transformed into the isoschizozygane skeleton upon treatment with acid. A variation
利用交叉缀合的杂芳族甜菜碱的分子内1,4-偶极环加成,已经开发了一种有效的立体异构控制的途径,用于异麦芽糖胺生物碱核心。生成的环加合物经历了COS的损失,并且进一步的还原产生了5 a-氮杂ena庚烯中间体,其在用酸处理后被转化为异chi唑烷骨架。然后,采用这种策略的一种变体来合成zo唑烷生物碱(±)-倍他福洛平的六环骨架。合成的关键步骤对应于杂原子甜菜碱的分子内1,4-偶极环加成反应,该分子通过束缚的4-((2-硝基苯基)丁-3-烯基)侧链。硝基的催化还原,然后与NBS反应导致形成目标生物碱所需的五环二氢吲哚骨架。使用氧化环化作用封闭了zo唑烷骨架的最后一个环。