Structure–sweetness relationships for fructose analogs. Part I. Synthesis and evaluation of sweetness of 5-deoxy-D-threo-hexulose

Abstract

5-Deoxy-D-threo-hexulose ("5-deoxyfructose", "5-deoxysorbose") has been prepared in six steps from D-fructose. The reaction of 2,3-O-isopropylidene-β-D-fructopyranose with sulfuryl chloride afforded exclusively 5-chloro-5-deoxy-2,3-O-isopropylidene-α-L-sorbopyranose in the key step. "5-Deoxyfructose" exists only in the ²C₅(D) pyranoid form in solution, and was found to be much sweeter than L-sorbose and nearly as sweet as D-fructose. Comments on this unexpected sweetness result are given.