Thio-L-sorbose

An aldolase-based strategy conveniently provided access to thioketoses with sulfur in the ring. For example, RAMA-catalyzed carbon-carbon bond formation of a 3-thioglycerinaldehyde with dihydroxyacetone phosphate gave 6-thio-D-fructose 36 [32] (Figure 9.8), also available by enzymatic isomerization of 6-thio-D-glucose or 6-thio-L-sorbose with glucose isomerase (EC 5.3.1.5 vide infra) [32,41]. 

The resistance to iodide displacement of 1-O-sulfonyl derivatives of D-fructose and D-sorbose is well known,287 and selective displacement at C-6 of 2,3-0-isopropyIidene-l,6-di-0-p-tolylsulfonyl-D-fructo-furanose by sodium a-toluenethioxide in methanol gave 6-S-benzyl-2,3-0-isopropylidene-6-thio-l-0-p-tolylsulfonyl-D-fructofuranose in 74% yield.218... 

The following are not substrates D>allose, D-galactose 4-deoxy-glucose, 4>deoxy-fluoroglucose, 5-thio-D glucose, L-rhamnose, L-fucose, L-sorbose. 

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