Pure Appl. Chem., 2005, Vol. 77, No. 12, pp. 2111-2119
doi:10.1351/pac200577122111
Enantioselective addition of organozinc reagents to carbonyl compounds*
Miguel Yus and Diego J. Ramón
Instituto de Síntesis Orgánica y Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
Abstract:
Different chiral camphorsulfonamide derivatives containing a hydroxy or a sulfonamido functionality, as well as chiral 1,2-hydroxysulfonamides, have been evaluated as chiral promoters in the classical enantioselective addition of dialkylzinc reagents to aldehydes in the presence of titanium tetraisopropoxide (ee up to 96 %). Surprisingly, ligands with a structure of isoborneol are able to promote the related unknown addition to ketones (ee >99 %), the best ligand being the exo-diol derived from 1,2-trans-biscamphorsulfonamidocyclohexane (HOCSAC).
Keywords: camphorsulfonamide; dialkylzinc; Enantioselective; hydroxysulfonamides; organozinc reagents; titanium tetraisopropoxide.
*Paper based on a presentation at the 7th IUPAC International Conference on Heteroatom Chemistry (ICHAC-7), Shanghai, China, 21-25 August 2004. Other presentations are published in this issue, pp. 1985-2132.