4-Hydroxy-2,5-dimethyl-3 -furanone formation from precursors

In addition to terpenes, carbohydrates serve as a precursor of furanones in plants. The formation of 2,5-dimethyl-4-hydroxy-2H-furan-3-one (DMHF) is an example. This compound, and various forms thereof, are key to the aroma of strawberry. Several researchers have studied the biochemical pathways responsible for the formation of this compound [34,35]. The pathway presented in Figure 4.10 illustrates DMHF formation from its key precursor, 6-deoxy-D-fructose. 

The reaction of a-bromoacetals with trimethylsilylenolates catalyzed by titanium tetrachloride provides /3-alkoxy-y-bromoketones, which are useful furan precursors (Scheme 33) (75CL527). A new synthesis of acylfurans is exemplified by the formation of the 3-acetyl derivative (146) by heating the brdmoalkene (145) (78JOC4596). 2,2-Dimethyl-3(2//)-furanone (148) has been synthesized from 3-hydroxy-3-methylbutan-2-one treatment with sodium hydride and ethyl formate gave the hydroxymethylene derivative (147), which was cyclized and dehydrated to the furanone (148) with hydrochloric acid (Scheme 34) (71TL4891). O... 

Among other compounds, C-3 fragments are also precursors for the formation of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (II, furaneol), which can be formed, e. g., from 2-hydroxypropanal and its oxidation product, 2-oxopropanal (I in Formula 4.47). The substitution of 2-oxobutanal for 2-oxopropanal yields the homologous ethylfuraneol. In a similar way, 3-hydroxy-... 

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