A direct and high yielding route to 2-(5-tetrazolyl) substituted benzopyran-4-ones: synthesis of pranlukast

…, IS Mann, VJ Novack, PW Oxley, JK Quick…

Index: Geen, Graham R.; Giles, Robert G.; Grinter, Trevor J.; Hayler, John D.; Howie, Simon L. B.; Johnson, Graham; Mann, Inderjit S.; Novack, Vance J.; Oxley, Paul W.; Quick, John K.; Smith, Neil Synthetic Communications, 1997 , vol. 27, # 6 p. 1065 - 1073

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Citation Number: 5

Abstract

Abstract A direct and high yielding route to 2-(5-tetrazolyl) benzopyran-4-ones 1, including pranlukast 1a is described. This involves the Claisen condensation reaction between the relevant hydroxyacetophenone 2 and the ethyl ester of tetrazole-2-carboxylic acid 5 to give the 1, 3-diketone 6, which is then cyclised to give the desired benzopyran-4-ones 1.