Facile syntheses of 4-perfluoroalkyl-6-(alpha-furyl)-2-pyranones and methyl 4-(alpha-furoyl)-3-perfluoroalkyl-3-butenoates

In the presence of K2CO3, reaction of (alpha-furoyl)methyltriphenylphosphon ium bromide (1) with methyl 2-perfluoroalkynoates (2) in CH2Cl2 at room tem perature gave methyl 4-(alpha-furoyl)-2-triphenylphospknoranylidene-3-perfl uoroalkyl-3-butenoates (3) in excellent yields. 4-Perfluoroalkyl-6-(alpha-f uryl)-6-phyranones (4) and methyl 4-(alpha-furoyl)-3-perfluoroalkyl-3-buten oates (5) were obtained in high yield by hydrolysis of these phosphoranes ( 3) with hot aqueous methanol. The butenoates (5) were isolated chromatograp hically as mixtures of Z and E isomers, the ratios of which were estimated by H-1 NMR Reaction mechanisms are proposed to account for the formation of products 3, 4 and 5. (C) 1999 Elsevier Science S.A. All rights reserved.