Reaktion #1973906

Reaktionsgleichung

tert-amyl alcohol

fluoride

sodium methoxide

methyl fructofuranoside

cesium fluoride

→

6-deoxy-6-fluoro-D-fructose

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigein moderate yield over the two steps
2. 2
   SonstigeThe silyl protecting group is removed by treatment with aqueous trifluoroacetic acid in dichloromethane
3. 3
   Sonstigeto provide intermediate (VI) in 91% (Tatibouet et al., 2000)

Vorschrift

As a starting material, D-fructose is inexpensive and readily available. Briefly, treatment of fructose with acidic methanol affords a mixture of methyl α/β-D-fructofuranosides (II, III) which may be separated using standard silica gel chromatography or, alternatively, carried on as a mixture (FIG. 1). Selective protection of the primary C-6 hydroxyl with tert-butyldimethylchlorosilane (TBDMSCl) in pyridine, followed by global acetylation produces intermediate (V) in moderate yield over the two steps. The silyl protecting group is removed by treatment with aqueous trifluoroacetic acid in dichloromethane to provide intermediate (VI) in 91% (Tatibouet et al., 2000). Compound (VI) is then fluorinated via triflation under standard conditions and immediate treatment with three equivalents of cesium fluoride in refluxing tert-amyl alcohol (Kim et al., 2006). The quick and clean fluoride displacement reaction is useful for installation of [18F] for imaging experiments. Standard deprotection of the acetates using sodium methoxide followed by acidic hydrolysis of the methyl fructofuranoside provides 6-deoxy-6-fluoro-D-fructose (IX) as a white solid in 62% (two steps).

Quelle