Reductive deoxygenation of alcohols by PMHS assisted by iodide†

Abstract

The deoxygenation of alcohols is an important and extensively studied research area in modern organic chemistry. However, a chemoselective and clean method is still required for large-scale biochemical production. Herein, we report a strategy for the deoxygenation of alcohols into alkanes using polymethylsiloxane (PMHS) as the reductant with the assistance of iodide. This method, which does not require a metal catalyst, furnishes 5-methylfurfural in 99% yield from hydroxymethylfurfural within 2 h at 140 °C and tolerated a broad scope of functional groups, including phenyl, furanyl, naphthyl, thienyl and allyl alcohol derivatives. A kinetic study revealed that cleavage of the C–I bond formed by the substitution of the hydroxyl group by iodide is the rate-determining step. A mechanistic study suggested a radical mechanism for this alcohol deoxygenation reaction.