Hf(OTf)4-Catalyzed Three-Component Synthesis of N-Carbamate-Protected β-Amino Ketones

Hafnium(IV) triflate (Hf(OTf)(4)) has been identified as a potent catalyst for the direct three-component synthesis of beta-carbamate ketones. This new method, featuring a low catalyst loading, fast reaction rate, and solvent-free conditions, provided facile access to a diversity of carbamate-protected Mannich bases. A mechanistic investigation indicated that the three-component reaction proceeds via sequential aldol condensation and aza-Michael addition, but not the Mannich-type pathway.

Automated summary

Hafnium(IV) triflate (Hf(OTf)(4)) has been identified as a potent catalyst for the direct three-component synthesis of beta-carbamate ketones. This new method, featuring a low catalyst loading, fast reaction rate, and solvent-free conditions, provides easy access to a variety of carbamate-protected Mannich bases. Mechanistic investigation reveals that the three-component reaction proceeds through sequential aldol condensation and aza-Michael addition, rather than the Mannich-type pathway.