A novel route to 6-substituted and 5,6-disubstituted 2-pyrones

6-Alkyl- and 6-(1-alkenyl)-5-iodo-2-pyrones, which are available as major p roducts by reaction of the corresponding (Z)-2-en-4-ynoic acids with iodine and NaHCO3 in CH3CN, undergo insertion of activated zinc metal into their carbon-iodine bond to provide the corresponding 5-(iodozinc)-2-pyrones. Hyd rolysis of these organometallics gives 6-substituted 2-pyrones in satisfact ory yields including two natural products. On the other hand, the Pd-cataly zed reaction of the organozines either with an activated alkenyl halide or with activated and deactivated (hetero)aryl halides provides 5,6-disubstitu ted 2-pyrones in fair to good yields. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.