Highly enantioselective cyanation of aldehydes catalyzed by a multicomponent titanium complex

J Org Chem. 2006 Jul 21;71(15):5732-6. doi: 10.1021/jo060772z.

Abstract

A new multicomponent bifunctional catalytic system based on a titanium complex was used for the efficient enantioselective cyanation of aldehydes. The catalyst was readily prepared from tetraisopropyl titanate (Ti(Oi-Pr)4), (S)-6,6'-dibromo-1,1'-bi-2-naphthol (1e), cinchonine (2a), and (1R,2S)-(-)-N-methylephedrine (3b). It was revealed that the combination of 1e, 2a, 3b, and Ti(IV) was essential in this cyanation. The reaction proceeded smoothly in the presence of a catalytic amount of the multicomponent catalyst to afford the desired cyanohydrins ethyl carbonates in moderate to excellent isolated yields (up to 95%) with high enantioselectivities (up to 94% ee). A catalytic cycle based on experimental phenomena was proposed to explain the origin of the asymmetric induction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes / chemistry*
  • Catalysis
  • Cyanates / chemistry*
  • Molecular Structure
  • Stereoisomerism
  • Titanium / chemistry*

Substances

  • Aldehydes
  • Cyanates
  • Titanium