Selective synthesis of natural and unnatural 5,6-disubstituted 2(2H)-pyranones via iodolactonization of 5-substituted (Z)-2-en-4-ynoic acids

摘要

Reaction of 5-substituted (Z)-2-en-4-ynoic acids with iodine and NaNHCO_3 in CH_3CN or with ICl in CH_2Cl_2 affords mixtures of (E)-5-(1-iodoylidene)-2-(5H)-furanones and 6-substituted 5-iodo-2(2H)-pyranones in which these last compounds are the major products.