Scandium(III) Fluoride as a Novel Catalyst for Hydroxymethylation of Dimethylsilyl Enolates in Aqueous Media
19 May 2008 (online)
Hydroxymethylation of dimethylsilyl (DMS) enolates using aqueous formaldehyde solution is catalyzed by scandium(III) fluoride (ScF3) in aqueous media to give the corresponding β-hydroxy ketones in good to excellent yields. Whilst the DMS enolate reactions are facile the TMS enolates react sluggishly under the same conditions. ScF3 has been shown to be a unique catalyst for this reaction.
scandium - scandium fluoride - catalysis - hydroxymethylation - aqueous media
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References and Notes
A commercially available HCHO solution including 5-10% MeOH stabilizer was used.9
Typical Procedure for Hydroxymethylation Reactions: To a solution of ScF3 (0.03 mmol) in THF-H2O (2.7 mL/0.22 mL) was added 36% aq solution of formaldehyde (1.5 mmol) and (Z)-dimethyl(1-phenylprop-1-enyloxy)silane (1ab, 0.3 mmol). The reaction mixture was stirred for 40 h at r.t. The mixture was then diluted with H2O (10 mL), and the aqueous layer was extracted with CH2Cl2 (3 × 20 mL). The combined organic extracts were washed with brine, and dried over anhyd Na2SO4. After filtration, the solvent was removed in vacuo. The residue was purified by preparative TLC (elution with n-hexane-EtOAc = 3:2) to give 3-hydroxy-2-methyl-1-phenylpropane-1-ono (2a) in 89% yield.