Highly enantio- and diastereoselective organocatalytic desymmetrization of prochiral cyclohexanones by simple direct aldol reaction catalyzed by proline

Xavier Companyó, Guillem Valero, Luis Crovetto, Albert Moyano, Ramon Rios

Research output: Contribution to journalArticlepeer-review

101 Scopus citations

Abstract

A straightforward, efficient and highly enantio- and diastereoselective desymmetrization of 4-substituted cyclohexanones using proline as catalyst was investigated. Once a suitable catalyst system was obtained for the desymmetrization of 4-methylcyclohexanone (1a) by aldol addition, the reaction of different 4-substituted cyclohexanones with 4-nitrobenzaldehyde was studied. The final aldol adduct in excellent enantioselectivities and in good to excellent yields and diastereoselectivities was obtained. Both the UV and fluorescence spectra of the additive 4 f with different amounts of proline was used to investigate the stoichiometry between additives and proline in CHCl3. The UV spectrum of compound 4 f showed a slight blue-shift to 360 nm, an absorbance increase at 360 nm and an isosbestic point around 310 nm with increasing concentration of proline. It was demonstrated that the use of simple hydrogen-bond donors as additives increases dramatically the efficiency of the process.

Original languageBritish English
Pages (from-to)6564-6568
Number of pages5
JournalChemistry - A European Journal
Volume15
Issue number27
DOIs
StatePublished - 6 Jul 2009

Keywords

  • Aldol reaction
  • Desymmetrization
  • Hydrogen bonds
  • Organocatalysis
  • Proline

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