Toward a total synthesis of stigmatellin; obtention of an advanced fragment from gallic acid

Treatment by a base, then an acid, of the ester 3, which was prepared by st arting from gallic acid 7a, afforded the chromone 6c, whose Swern oxidation , followed by condensation of the resulting aldehyde 6a with the trienyl li thium derivative 13b and methyl iodide, furnished products isomeric with, b ut not strictly identical to, an authentic sample of O-benzyl stigmatellin Ic. (C) 2000 Elsevier Science Ltd. All rights reserved.