Synthesis 2010(11): 1909-1923  
DOI: 10.1055/s-0029-1218751
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart ˙ New York

Constructing Quaternary Centers of Chirality: The Lanthanide Way to Trifluoromethyl-Substituted Tertiary Alcohols

Fernando Tur, Javier Mansilla, Victor J. Lillo, José M. Saá*
Departamento de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
Fax: +34(971)173426; e-Mail: jmsaa@uib.es;
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Publikationsverlauf

Received 26 February 2010
Publikationsdatum:
23. April 2010 (online)

Abstract

Enantiomerically enriched trifluoromethyl-substituted alcohols having a quaternary center of chirality can be prepared by the catalytic enantioselective addition of carbon nucleophiles to trifluoromethyl ketones, trifluoropyruvates, or the like. In particular, chiral lanthanide(III) salt complexes of 3,3′-bis[(diethylamino)­-methyl­]-1,1′-binaphthalene-2,2′-diol (Binolam) were examined as catalysts for the enantioselective addition of nitromethane to alkyl, aryl, or alkynyl trifluoromethyl ketones. The corresponding nitro­aldols were obtained in moderate chemical yields and good enantio­selectivities. The absolute configuration of the product was determined to be S when the lanthanum complex (Δ,S,S,S)-[(Binolam­)3La(OTf)3] was used as a catalyst (25 mol%) in the presence of an equivalent amount of 1,8-bis(dimethylamino)naphthalene in anhydrous acetonitrile. The nitroaldol adducts were reduced to the corresponding amino alcohols by nickel boride (nickel chlor­ide/sodium tetrahydroborate) in methanol.

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Personal communication from Prof. Sanzhong Luo.