Coordination-induced axial chirality controls the metal-centred configuration in a stereogenic-at-iron catalyst.

A new approach is introduced to control the metal-centred configuration of stereogenic-at-iron catalysts by utilizing axial ligand chirality, which becomes locked upon metal coordination. This strategy is applied to an iron catalyst containing two chelating -(2-pyridyl)-substituted triazol-5-ylidene mesoionic carbenes (MICs) resulting in a helical topology with a stereogenic iron centre.

Synthesis of Iron(IV) Alkynylide Complexes and Their Reactivity to Form 1,3-Diynes.

The isolation of thermally unstable and highly reactive organoiron(IV) complexes is a challenge for synthetic chemists. In particular, the number of examples where the C-based ligand is not part of the chelating ligand remains scarce. These compounds are of interest because they could pave the way to designing catalytic cycles of bond forming reactions proceeding via organoiron(IV) intermediates.

β-Tryptophans by Iron-Catalyzed Enantioselective Amination of 3-Indolepropionic Acids.

A straightforward and general strategy for the catalytic asymmetric synthesis of β-tryptophans by carboxylic-acid-directed intermolecular C-H amination has been developed. The iron-catalyzed C-H amination of 3-indolepropionic acids with BocNHOMs (Boc, -butyloxycarbonyl; OMs, methylsulfonate) in the presence of the base piperidine provides N-Boc-protected β-tryptophans in a single step with high enantiomeric excess (ee) of up to >99%. Mechanistic experiments and density functional theory calculations support a mechanism through carboxylate-directed iron-mediated C(sp)-H nitrene insertion.

Stereogenic-at-iron mesoionic carbene complex for enantioselective C-H amidation.

Electronically tuned -symmetric stereogenic-at-iron complexes, featuring strongly σ-donating 1,2,3-triazolin-5-ylidene mesoionic carbene (MIC) ligands, exhibit enhanced catalytic efficiency compared to conventional imidazol-2-ylidene analogs, as demonstrated in nitrene-mediated ring-closing C(sp)-H amidation reactions. Furthermore, a chiral pinene-derived pyridyl triazole ligand enables a highly diastereoselective synthesis of a non-racemic chiral iron catalyst, thereby controlling the absolute configuration at the metal center, as confirmed by NMR and X-ray crystallography. This pinene-modified stereogenic-at-iron MIC complex demonstrates high catalytic activity and a respectable asymmetric induction in the ring-closing C(sp)-H amination of -benzoyloxyurea, yielding 2-imidazolidinones with enantiomeric ratios of up to 92 : 8.

Multinuclear Beryllium Chloro Carboxylates.

Reaction of 1 equiv of BeCl with mesityl (Mes) or -tolyl (-Tol) carboxylic acid in benzene gives hexanuclear heterocyles [BeCl(MesCO)] and [BeCl(-TolCO)], respectively. Small amounts of the oxocarboxylates [BeO(MesCO)] and [BeO(-TolCO)] are also formed. If chloroform is used as the solvent, a mixture of these complexes together with the unprecedented tertranuclear cage compounds [BeCl(MesCO)] and [BeCl(-TolCO)] is obtained.