Chiral Phosphanylferrocenecarboxamides with Amino Acid Pendant Groups as Ligands for Cu‐Mediated Asymmetric Conjugate Additions of Diethylzinc to Chalcones – Structural Characterisation of Precursors to the Cu Catalyst

Abstract

A series of chiral phosphanylferrocenecarboxamides was prepared by treatment of either 1Ј-(diphenylphosphanyl)-ferrocene-1-carboxylic acid (Hdpf) or its planar-chiral 1,2-isomers with amino acid methyl esters in the presence of peptide coupling agents. The compounds were characterised by spectroscopic methods, and the crystal structure of one representative was determined by X-ray diffraction. Catalytic testing of these donors in Cu-catalysed asymmetric conjugate additions of diethylzinc to chalcones revealed that the reaction outcomes were highly sensitive to the ligand structure and the reaction conditions (copper source and solvent),

Synthesis of phosphinoferrocene amides and thioamides from carbamoyl chlorides and the structural chemistry of Group 11 metal complexes with these mixed-donor ligands

“…Compound 7d gives rise to a broad doublet at δ P −0.3 with 1 J (Ag,P) ≈ 510 Hz. It is also noteworthy that the 31 suggest the solid state structures to be retained even in solution, though perhaps with some structural dynamics.…”

(S)-2-[(N-arylamino)methyl]pyrrolidines-Based PhosphoramiditeP,N-Ligand Library for Asymmetric Metal-Catalyzed Allylic Substitution and Conjugate 1,4-Addition

“…[a] All reactions were carried out with 2.2 mol% of Cu(OTf) 2 in toluene at – 20 °C for 15 h. [b] The enantiomeric excess of 15 was determined by HPLC (Daicel Chiralcel OD−H, C 6 H 14 / i PrOH=99/1, 0.75 mL/min, 254 nm, t ( R )=11.6 min, t ( S )=12.3 min). [c] The absolute configuration was assigned by comparison of the HPLC retention times reported in the literature …”

“…[c] The absolute configuration was assigned by comparison of the HPLC retention times reported in the literature. [19]…”

The Synthesis of Chiral Phosphorus Ligands for use in Homogeneous Metal Catalysis

“…Unfortunately, poor ee values were noted, which might be attributed to the high conformational flexibility of the ligand in comparison to the much more efficient aminophosphine ligands introduced by Noyori. [83] The ligands were investigated as chiral auxiliaries in the Cumediated asymmetric conjugate addition of diethylzinc to chalcones, where up values to 90 % ee were noted. [82] The ligands were tested in the Pd-catalyzed asymmetric alkylation for which up to 94 % ee was achieved.…”

“…A series of diastereromeric ferrocenylphosphino carboxamides were synthesized starting from carboxylic acid precursors by condensation with enantiopure amino acids (Scheme 34). [83] The ligands were investigated as chiral auxiliaries in the Cumediated asymmetric conjugate addition of diethylzinc to chalcones, where up values to 90 % ee were noted.…”