Oxidation of 2,4-Alkadienoic Esters with Selenium Dioxide. A New Synthesis of Furans and Selenophenes

Abstract

Abstract Direct oxidation of 2,4-alkadienoic esters with selenium dioxide gave 5-alkyl-2-furancarboxylic esters along with 5-alkyl-2-selenophenecarboxylic esters. Ethyl 5-methylfurancarboxylate was converted to 5-hydroxymethyl-2-furancarbaldehyde, a component of honey, via ethyl 5-bromomethyl-2-furancarboxylate (5) in good yield. The compound 5 was converted to (5-ethoxycarbonyl-2-furyl)methyl dimethyldithiocarbamate possessing fungicidal activity. Reaction of triphenylphosphonium salt of 5 with nonanal gave ethyl 5-(1-decenyl)-2-furancarboxylate (E/Z=88:12) in 86% yield. Ethyl 5-methyl-2-selenophenecarboxylate was also converted to ethyl 5-(1-decenyl)-2-selenophenecarboxylate (E/Z=7:3) in 30% total yield.