Organocatalyzed asymmetric Michael addition by an efficient bifunctional carbohydrate-thiourea hybrid with mechanistic DFT analysis

Org Biomol Chem. 2016 Dec 28;14(48):11454-11461. doi: 10.1039/c6ob02158a. Epub 2016 Nov 24.

Abstract

A series of thiourea based bifunctional organocatalysts having d-glucose as a core scaffold were synthesized and examined as catalysts for the asymmetric Michael addition reaction of aryl/alkyl trans-β-nitrostyrenes over cyclohexanone and other Michael donors having active methylene. Excellent enantioselectivities (<95%), diastereoselectivities (<99%), and yields (<99%) were attained under solvent free conditions using 10 mol% of 1d0. The obtained results were explained through DFT calculations using the B3LYP/6-311G(d,p)//B3LYP/6-31G(d) basic set. The QM/MM calculations revealed the role of cyclohexanone as a solvent as well as reactant in the rate determining step imparting 31.91 kcal mol-1 of energy towards the product formation.

MeSH terms

  • Alkenes / chemical synthesis*
  • Alkenes / chemistry
  • Amines / chemistry
  • Carbohydrates / chemistry*
  • Catalysis
  • Cyclohexanones / chemical synthesis*
  • Cyclohexanones / chemistry
  • Molecular Structure
  • Nitro Compounds / chemical synthesis*
  • Nitro Compounds / chemistry
  • Quantum Theory*
  • Stereoisomerism
  • Thiourea / chemical synthesis
  • Thiourea / chemistry*

Substances

  • Alkenes
  • Amines
  • Carbohydrates
  • Cyclohexanones
  • Nitro Compounds
  • cyclohexanone
  • Thiourea