Scandium(III) Fluoride as a Novel Catalyst for Hydroxymethylation of Dimethylsilyl Enolates in Aqueous Media

Masaya Kokubo; Shu Kobayashi

doi:10.1055/s-2008-1078409

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Scandium(III) Fluoride as a Novel Catalyst for Hydroxymethylation of Dimethylsilyl Enolates in Aqueous Media

Masaya Kokubo, Shu Kobayashi*
Department of Chemistry, School of Science and Graduate School of Pharmaceutical Sciences, The University of Tokyo, The HFRE Division, ERATO, Japan Science and Technology Agency (JST), Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Fax: +81(3)56840634; e-Mail: shu_kobayashi@chem.s.u-tokyo.ac.jp;

Abstract

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Abstract

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.

Key words

scandium - scandium fluoride - catalysis - hydroxymethylation - aqueous media

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References

References and Notes

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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.