Synthesis of 7-functionalized γ-lactones from furfural

Condensation of the methyl ketones, 2-propanone, 2-butanone, 2-pentanone, 2-hexanone and 2-heptanone with furfural under alkaline conditions yielded the corresponding furfurylidene ketones arising from condensation at the methyl group. Hydrolytic ring cleavage of the furfurylidene ketones under acidic conditions yielded the corresponding 4,7-dioxocarboxylic acids. Borohydride reduction of these acids followed by acidification yielded the corresponding 7-hydroxy-γ-lactones. The 7-hydroxy group could be oxidized to a keto group or acetylated easily. The 7-hydroxy-, 7-oxo- and 7-acetoxy-γ-lactones synthesized are not natural compounds, and are being reported for the first time. Their structures were established by Infra Red (IR), 1H and 13C Nuclear Magnetic Resonance (NMR), 2D NMR (COSY and HETCOR) spectroscopy and Gas Chromatography-Mass Spectrometry (GC-MS).

Keywords: Dioxocarboxylic acids, furfural, furfurylidene ketones, gamma lactones  

doi:10.4038/jnsfsr.v36i3.153  

Journal of the National Science Foundation of Sri Lanka 36 (3) 183-184