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Synthesis 2001; 2001(1): 0049-0051
DOI: 10.1055/s-2001-9759
short paper
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Reaction of 4-Hydroxycoumarin with α,β-Unsaturated Iminium Salts: A Straightforward, Regioselective Entry to Pyranocoumarin Derivatives

Giancarlo Cravotto* , Gian Mario Nano, Silvia Tagliapietra
  • *Dipartimento di Scienza e Tecnologia del Farmaco, Via Giuria 9, 10125 Torino, Italy; Fax +39(11)6 70 76 87; E-mail: cravotto@pharm.unito.it
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Publication Date:
31 December 2001 (online)

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4-Hydroxycoumarin reacts with α,β-unsaturated iminium salts derived from enals to give 1,2-addition products, exclusively. The resulting adducts further react intramolecularly, affording substituted 2H-pyrrano[3,2-c]coumarins in good yields. α,β-Unsaturated iminium salts derived from enones afford substituted 3,4-dihydro-2-hydroxy-2H,5H-pyrano[3,2-c]coumarins by intramolecular cyclisation of the Michael adduct.

iminium salts - pyranocoumarins - tandem reaction - natural products - cycloadditions

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