Directed ortho metalation - cross coupling links. Carbamoyl rendition of the baker-venkataraman rearrangement. Regiospecific route to substituted 4-hydroxycoumarins
Alexey V. Kalinin, Alcides J. M. da Silva, Claudio C. Lopes, Rosangela S. C. Lopes and Victor Snieckus*
*Department of Chemistry, Queen's University, Kingston, ON, K7L 3N6, Canada, Email: snieckuschem.queensu.ca
A. V. Kalinin, A. J. M. Da Silva, C. C. Lopes, R. S. C. Lopes, V. Snieckus, Tetrahedron. Lett., 1998, 39, 4995-4998.
A new carbamoyl Baker-Venkataraman rearrangement allows a general synthesis of substituted 4-hydroxycoumarins in good overall yields. Intermediate arylketones are efficiently prepared via a Directed ortho Metalation - Negishi cross coupling protocol from arylcarbamates. The overall sequence provides a regiospecific anionic Friedel-Crafts complement for the construction of ortho-acyl phenols and coumarins.
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