Enantioselective borane reduction of ketones with oxazaborolidines boron-bound to nickel boride nanoparticles

Tetrahedron Letters

Volumn 40, Issue 48, 1999, Pages 8375-8378

  Molvinger, Karine ^a   Lopez, Monique ^a   Court, Jean ^a  

^a UNIVERSITÉ JOSEPH FOURIER   (France)

Author keywords

Borane; Chiral alcohol; Enantioselective reduction; Heterogeneous catalysts; Oxazaborolidine

Indexed keywords

ACETOPHENONE DERIVATIVE; ALCOHOL DERIVATIVE; BORANE DERIVATIVE; NANOPARTICLE; NICKEL; ORGANOBORON DERIVATIVE; PHENETHYL ALCOHOL;

ARTICLE; CATALYSIS; ENANTIOMER; REDUCTION;

EID: 0033607610     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)01871-7     Document Type: Article

References (13)

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2. Jones, T. K.; Mohan, J. J.; Xavier, L. C.; Blacklock, T. J.; Mathre, D. J.; Sohar, P.; Tracy Turner Jones, E.; Reamer, R. A.; Roberts, F. E.; Grabowski, E. J. J. J. Org. Chem. 1991, 56, 763.
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7. -1.
8. Half an equivalent was formed at room temperature which we attribute to the reaction of the hydroxyl group and half an equivalent was produced on refluxing which we attribute to the reaction of the amino group, well positioned for reacting with the same boron atom.
9. Stewart, A. C.; Schaeffer, G. W. J. Inorg. Nucl. Chem. 1956, 3, 194.
10. x, where x is the ratio amino alcohol:boron i.e.: 0.05.
11. Quallich, G. J.; Woodall, T. M. Tetrahedron Lett. 1993, 34, 4145. This result was obtained with 5 mol% catalyst. However, according to the authors, greater amounts of catalyst did not improve the enantioselectivity with aromatic ketones.
12. Mathre, D. J.; Thompson, A. S.; Douglas, A. S.; Hoogsteen, K.; Carroll, J. J.; Corley, E. G.; Grabowski, E. J. J. J. Org. Chem. 1993, 58, 2880.
13. The procedure: 1 equivalent of borane-THF (1 M) was added to a stirred suspension of 1 equivalent of oxazaborolidine bound to nickel boride in 100 mL of THF at room temperature under nitrogen after 30 min, the mixture was treated with 1 equivalent of ketone and stirring was continued at room temperature until the reaction was complete (GLC analysis, usually 1-1.5 h). The solids were allowed to settle and the liquid phase was removed through a transfer tube by means of a pressure differential, the catalyst being left in the flask for reuse. The liquid phase was diluted with 2 M HCl and extracted with ethyl acetate, which was then washed with saturated aqueous NaCl, dried, and evaporated. The enantiomeric purity of the product was determined by capillary GC with a chiral column (hydrodex b cyclodextrin, 25 m×0.25 mm (Macherey-Nagel)).