Hf(OTf)4 as a Highly Potent Catalyst for the Synthesis of Mannich Bases under Solvent-Free Conditions

Molecules. 2020 Jan 17;25(2):388. doi: 10.3390/molecules25020388.

Abstract

Hf(OTf)4 was identified as a highly potent catalyst (0.1-0.5 mol%) for three-component Mannich reaction under solvent-free conditions. Hf(OTf)4-catalyzed Mannich reaction exhibited excellent regioselectivity and diastereoselectivity when alkyl ketones were employed as substrates. 1H NMR tracing of the H/D exchange reaction of ketones in MeOH-d4 indicated that Hf(OTf)4 could significantly promote the keto-enol tautomerization, thereby contributing to the acceleration of reaction rate.

Keywords: Mannich reaction; hafnium triflate; mechanism; solvent-free; β-amino carbonyl compound.

MeSH terms

  • Catalysis
  • Hafnium / chemistry*
  • Ketones / chemistry*
  • Mannich Bases / chemistry
  • Mesylates / chemistry*
  • Molecular Structure
  • Proton Magnetic Resonance Spectroscopy
  • Solvents

Substances

  • Ketones
  • Mannich Bases
  • Mesylates
  • Solvents
  • trifluoromethanesulfonic acid
  • Hafnium