Catalytic stereoselective Mannich-type reactions for construction of fluorinated compounds

For its unique role in developing and designing new bioactive materials and healthcare products, fluoro-organic compounds have attracted remarkable interest. Along with ever-increasing demand for a wider availability of fluorine-containing structural units, a large diversity of methods has been introduced to incorporate fluorine atoms specially in a stereoselective fashion. Among them, catalytic Mannich reaction can proceed with a broad variety of reactants and open clear paths for the synthesis of versatile amine synthons in the synthesis of natural product and pharmaceutical molecules. This review provides an overview of the employment of catalytic asymmetric Mannich reactions in the synthesis of fluorine-containing amine compounds and highlights the conceivable distinct mechanisms.

β,β-Dialkyl γ-amino γ-trifluoromethyl alcohols from trifluoromethyl (E)-aldimines by a one-pot solvent-free Mannich-type reaction and subsequent reduction

A diastereoselective one-pot solvent-free Mannich-type addition of α-alkyl aldehydes to trifluoromethyl (E)-aldimines, which first act as bases and then as electrophiles, leads to β,β-dialkyl γ-amino γ-CF₃ alcohols in good yields, after reduction.

Stereoselective ZrCl4-Catalyzed Mannich-type Reaction of β-Keto Esters with Chiral Trifluoromethyl Aldimines

A method for the synthesis of fluorinated β'-amino β-dicarbonyl compounds using a Zr-catalyzed Mannich-type reaction has been developed, starting from N-protected trifluoromethyl aldimines and cyclic or acyclic β-keto esters bearing different ester residues. The in situ generated metallic complex reacted with optically pure trifluoromethyl aldimine derived from (R)-α-methylbenzylamine, giving a highly diastereoselective asymmetric Mannich-type addition with formation of a chiral quaternary center. The absolute configuration at the new chiral centers was assigned through two-dimensional nuclear Overhauser effect spectroscopic analysis coupled with computational studies.