Expedient synthesis of a highly substituted tropolone via a 3-oxidopyrylium [5+ 2] cycloaddition reaction

…, AVW Mayweg, GJ Pritchard, RM Adlington

Index: Baldwin, Jack E.; Mayweg, Alexander V.W.; Pritchard, Gareth J.; Adlington, Robert M. Tetrahedron Letters, 2003 , vol. 44, # 24 p. 4543 - 4545

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Citation Number: 30

Abstract

An expedient ten-step synthesis of a substituted tropolone is described. The synthesis involves a 3-oxidopyrylium [5+ 2] cycloaddition reaction with acrylonitrile as the key step, affording a highly functionalized [3.2. 1]-bicycle 10 as a single regioisomer. The nitrile substituent of the reduced cycloadduct 12 permits efficient ether-bridge cleavage and tropolone 15 is obtained after a final bis-oxidation procedure. The pyranulose acetate ...