An efficient synthesis of 4-alkenyl/alkynyl-6-methyl-2-pyrones via Pd-catalysed coupling on 4-bromo-6-methyl-2-pyrone

We herein report the efficient syntheses of biologically active 4-alkenyl- and 4-alkynyl-6-methyl-2-pyrones using Pd-catalysed coupling procedures. A palladium on carbon/triphenylphosphine combination is shown to be the most effective catalyst for Sonogashira cross-coupling of several terminal acetylenes with 4-bromo-6-methyl-2-pyrone in yields of up to 95%. (C) 2002 Elsevier Science Ltd. All rights reserved.