Chemistry and applications of phosphonium and arsonium ylides - XXVI. Synthesis of arsonium ylides containing perfluoroalkyl group and study on theirhydrolysis

In the presence of K2CO3, reaction of (alpha - furoyl)methyl - arsoniumbrom ide(1) with methyl 2-perfluoroalkynoates(2) in methylene chloride at 0 simi lar to 5 degrees C afforded the adduct - methyl 4 - (alpha furoyl) - 2 - tr iphenylarsoranylidene - 3 - perfluoroalkyl - 3 - butenoates(3) in high yiel d. Hydrolysis of 3 in V(CH3OH): V(H2O) = 9:1 methanolic solution at room te mperature, 70 degrees C and 120 degrees C in a sealed tube respectively, 4 - perfluoroalkyl - 6 - (alpha - furyl) - 2 - pyranones(4) and methyl 4 - (a lpha - furoyl) 3 - perfluoroalkyl - 3 - butenoates(5) were obtained in exce llent yield. Compounds 4 and 5 could be separated by column chromatography. 5 is a mixture of Z - and E - isomers which couldn't be separated by colum n chromatography, but the ratio of Z - and E - isomers could be estimated b y H-1 NMR. The catalytic hydrolysis of compound 3 with silica gel and the m echanisms for the formation of products are also discussed in this paper.