作者:Faïza Diaba、Agustín Martínez-Laporta、Guilhem Coussanes、Israel Fernández、Josep Bonjoch
DOI:10.1016/j.tet.2014.11.044
日期:2015.6
The key steps of the synthetic approach are an atom transfer radical cyclization of a trichloroacetamide upon an enol acetate to generate the B ring, and a sulfone-based conjugated addition upon a β-methyl-α,β-unsaturated ketone to give the target azatricyclic ketone. Selecting the cation (K+ or Cs+) of the carbonate in the C ring-forming intramolecular Michael addition gives stereodivergent access to
已经合成了茶碱A型生物碱的ABC环系统。合成方法的关键步骤是将三氯乙酰胺在烯醇乙酸酯上进行原子转移自由基环化以生成B环,并在β-甲基-α,β-不饱和酮上进行基于砜的共轭加成以生成目标氮杂三环酮。在形成C环的分子内迈克尔加成中选择碳酸根的阳离子(K +或Cs +),可使立体异构地接近环化产物的两个差向异构体。