Pd-Catalyzed Ring Assembly by Vinylation and Intramolecular Heck Coupling: A Versatile Strategy Towards Functionalized Azadibenzocyclooctynes
作者:Michael Jäger、Helmar Görls、Wolfgang Günther、Ulrich S. Schubert
DOI:10.1002/chem.201202790
日期:2013.2.4
A new modular approach based on Pd‐catalyzed CC bond formation is presented for the assembly of a benzannulated azocine scaffold, the key intermediate in the synthesis of functionalized azadibenzocyclooctynes (aza‐DIBOs). The intramolecular ring‐closing Heck coupling was investigated by variation of the CX bond. The reaction rate is limited by the initial oxidative addition step and the regiochemistry
基于Pd催化的C A新模块化方法提出了一种用于组装一个苯基环化吖辛因支架,在官能化azadibenzocyclooctynes(氮杂DIBOS)的合成中的关键中间体的C键的形成。通过改变CX键研究了分子内闭环Heck偶联。反应速率受初始氧化加成步骤的限制,区域化学强烈依赖于辅助膦。在最佳条件下,分两步(无保护基团化学反应)或在一个锅中以71%的产率获得8-内基区域异构体,包括CN键的形成。原型N的辛炔三键的实际生成还描述了无需色谱纯化的-苯甲酰基氮杂-DIBO。NMR光谱和X射线晶体学分析阐明了包括环应变环辛炔在内的结构特征。合成的N-苯甲酰基氮杂-DIBO的高反应性在与烷基叠氮化物(k = 0.38 M -1 s -1)促进的叠氮化物-炔烃环加成反应中得到证明。