Discovering New Asymmetric Catalyses:
Enantioselective Synthesis of Chiral Tertiary Alcohols
Miguel Yus
Instituto de Síntesis Orgánica and Departamento de Química Orgánica, Facultad de Ciencias,
Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
yus@ua.es
Among asymmetric synthesis, the catalytic version of this process has received a great
attention in the last few years due to the possibility of preparing chiral molecules from prochiral
starting materials by using a chiral catalyst [1]. In general the catalyst belongs to one of the
following series: (a) metal-containing catalyst, (b) organocatalyst, and (a) biocatalyst (enzymes or
microorganisms). Considering the first group, usually the active species consists in a metal
component and a chiral ligand, which gives the anisotropic information necessary in order to get
the corresponding induction. Concerning different methodologies involving carbon-carbon bond
formation [2], one of the most studied has been the enantioselective addition of an organometallic
reagent to a prochiral carbonyl compound [3]. However, this process is especially difficult when
ketones are used as the electrophilic component [4], this reaction being of great interest because it
could be a way to generate chiral compounds bearing quaternary stereocenters [5]. In this
presentation, the last findings in the enantioselective addition of dialkylzinc reagents to proquiral
ketones using not only first generation (1), but also second (2) an third generation (3) ligands will
be shown (Chart 1) [6]. Especially in the case of the last ligands 3, they are interesting from a
practical point of view due the possibility of recovering and reusing them many times.
OH
OH
OH
R
SO2
NH
R
SO2
NH
R'
NHSO2R''
R'
NHSO2
SO2NHR
1
2
P
3
Chart 1.
References
[1] For a recent account, see: Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H. (Eds.), Comprehensive
Asymmetric Catalysis; Springer Verlag, Berlin: 1999; Supplement 1: 2004; Supplement 2: 2004.
[2] See, for instance: Seebach, D, Angew, Chem. Int. Ed. Engl. 1990, 29, 1320.
Example: A. Kumar, G. Ye, Y. Ahmadibeni, K. Parang, J. Org. Chem. 2006, 71, 7915.
[3] See, for instance: Yus, M.; Ramón, D. J. Recent Res. Devel. Org. Chem. 2002, 6, 297.
[4] For the first enantioselective addition of organozinc reagents to ketones, see: Ramón, D. J.;
Yus, M. Tetrahedron Lett.1998, 39, 1239.
[5] Ramón, D. J.; Yus, M. Angew. Chem. Int. Ed. 2004, 43, 284.
[6] For the last paper on this topic from our group, see: Forrat, V. J.; Ramón, D. J.; Yus, M.
Tetrahedron: Asymmetry 2007, 18, 400.