Synthesis and utilization of trifluoromethylated amino alcohol ligands for the enantioselective Reformatsky reaction and addition of diethylzinc to N-(diphenylphosphinoyl)imine

Synthesis of Trifluoromethylated Monoterpene Amino Alcohols

For the first time, monoterpene trifluoromethylated β-hydroxy-benzyl-O-oximes were synthesized in 81–95% yields by nucleophilic addition of the Ruppert–Prakash reagent (TMSCF3) to the corresponding β-keto-benzyl-O-oximes based on (+)-nopinone, (−)-verbanone and (+)-camphoroquinone. Trifluoromethylation has been determined to entirely proceed chemo- and stereoselective at the C=O rather than C=N bond. Trifluoromethylated benzyl-O-oximes were reduced to the corresponding α-trifluoromethyl-β-amino alcohols in 82–88% yields. The structure and configuration of the compounds obtained have been established.

Stereoselective Rearrangement of (Trifluoromethyl)prolinols to Enantioenriched 3-Substituted 2-(Trifluoromethyl)piperidines

3-Substituted 2-(trifluoromethyl)piperidines B were synthesized by ring expansion of (trifluoromethyl)prolinols A, which were obtained from L-proline via an aziridinium intermediate C. The ring opening of the (trifluoromethyl)aziridinium intermediate by different nucleophiles is regio- and diastereoselective.

Asymmetric synthesis of (αS)-polyfluoroalkylated N-Boc-prolinols by the diethyl zinc-induced asymmetric Meerwein–Ponndorf–Verley reduction of perfluoroalkyl N-Boc-pyrrolidyl ketones

Asymmetric synthesis of (αS)-polyfluoroalkylated prolinols by the asymmetric Meerwein–Ponndorf–Verley-type reduction of perfluoroalkyl N-Boc-pyrrolidyl ketones with Et₂Zn has been developed.

Enantioselective addition of dialkylzinc to aromatic aldimines mediated by camphor-derived chiral β-amino alcohols

The enantioselective addition of diethylzinc or dimethylzinc to N-(diphenylphosphinoyl)imines mediated by 1 or 2 could be achieved in high yields (70-97 %) and enantioselectivities (85-98 % ee). The catalytic loading of 1 or 2 a could be reduced to 10 mol % for methylation or ethylation of imines in high yields and enantioselectivities (79-96 %) when the reaction was conducted in the presence of 1.8 equiv of methanol. N-Monosubstituted amino alcohols induced higher enantioselectivity than their N,N-disubstituted congener in our catalytic system.

Practical synthesis of fluorine-containing α- and β-amino acids: recipes from Kiev, Ukraine

Naturally occurring compounds containing a C-F bond are extremely rare; only a handful of fluorine-containing carboxylic acids have been described so far. By contrast, man-made fluorine-containing derivatives of all major classes of biologically important compounds are extremely promising medicinal targets used in the elucidation of biochemical, metabolic transformations and the development of new pharmaceuticals. Among the fluorine-containing derivatives of natural products, fluorinated analogs of amino acids are of particular interest and medicinal potential. This article presents a concise review of various synthetic methods, developed by the Kiev's school of bioorganic chemistry, for the preparation of fluorine-containing analogs of α- and β-amino acids, α-hydroxy acids, amines, as well as their phosphorus and sulfur-derived compounds, in enantiomerically pure form. One of the major methodological goals of the study was practicality, which is understood by us as stereochemical generality, operational convenience and synthetic affordance for each reaction step and isolation of the target products. The synthetic methods developed by our group can be roughly divided in two general categories: fluorine-adaptation of known synthetic approaches and discovery of new reactions. The former approach is most prominently represented by asymmetric homologation of nucleophilic glycine equivalents using fluorinated substrates via alkyl halide alkylations, aldol and Michael addition reactions. A plethora of discovered unexpected reaction outcomes, in particular stereochemical, are emphasized in this review and the particular role of fluorine, in altering the 'normal' reaction result, is explained. The latter direction is notably represented by the novel 1,3-proton shift reaction, a biomimetic reductive amination of fluorinated carbonyl compounds to the corresponding amines and amino acids, as well as the development of α-fluoroalkyl epoxides as true fluorinated synthons for generalized asymmetric synthesis of various biologically relevant compounds. Despite the highly anticipated potential of fluorine-containing amino compounds, their medicinal chemistry still remains underexplored. The major obstacle, in our opinion, is that these selectively fluorinated compounds are generally unavailable to the medicinal chemists for comprehensive, systematic study. We hope this review of synthetic methods will highlight and bring attention to particular types of fluorinated amino acids and related compounds readily available on a laboratory scale using methods developed by our group.

Synthesis of β-amino-α-trifluoromethyl alcohols and their applications in organic synthesis

A comprehensive overview on methods applied for syntheses of β-amino-α-trifluoromethyl alcohols, including stereocontrolled variants, is presented. In addition, reported cases of the exploration of β-amino-α-trifluoromethyl alcohols for the preparation of trifluoromethylated peptidomimetics and other biologically active, fluorinated compounds are discussed. Attractive opportunities for their applications as organocatalysts are also presented.