Divergence en Route to Nonclassical Annonaceous Acetogenins. Synthesis of Pyranicin and Pyragonicin
作者:Daniel Strand、Per-Ola Norrby、Tobias Rein
DOI:10.1021/jo052233k
日期:2006.3.1
asymmetric HWE reactions, including the desymmetrization of a meso-dialdehyde and a parallel kinetic resolution of a racemic aldehyde. A stereoconvergent Pd-catalyzed substitution serves to install the C4 stereocenter in protected form with different orthogonal protective groups. A divergent strategy to form 1,4- and 1,6-diols, employing stereoselective Zn-mediated alkynylations, is used for completion
提出了从常见的后期中间体合成非经典的非丙酮产乙酸原素,吡喃霉素和吡喃霉素。关键元素的构建依赖于不对称的HWE反应,包括内消旋异构化-二醛和消旋醛的平行动力学拆分。立体收敛的Pd催化的取代用于以不同形式的正交保护基团以受保护的形式安装C4立体中心。采用立体选择性的Zn介导的炔基化反应形成1,4-和1,6-二醇的不同策略用于完成核心结构。值得注意的是,针对吡喃霉素的立体选择性偶联反应以高度官能化的片段进行。通过2,3,6-三取代的四氢吡喃亚基的所有立体异构体的发散合成,进一步扩展了该方法。