Formal Total Synthesis of Echinopines A and B via Cr(0)-Promoted [6π + 2π] Cycloaddition.


A concise formal synthesis of echinopines A and B is reported. The key [5.5.7] tricyclic intermediate, which has been previously used for the synthesis of echinopine A and B, was assembled using Cr(0)-promoted photochemical [6π + 2π] cycloaddition followed by a radical cyclization step. 
DOI: 10.1021/acs.orglett.5b01326


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