109 research outputs found
Metal-free borylation of heteroarenes using ambiphilic aminoboranes : on the importance of sterics in frustrated lewis pair C-H bond activation
Two novel frustrated Lewis pair (FLP) aminoboranes, (1-Pip-2-BH2-C6H4)2 (2; Pip = piperidyl)
and (1-NEt2-2-BH2-C6H4)2 (3; NEt2 = diethylamino), were synthesized and their structural features
were elucidated both in solution and in the solid state. The reactivity of these species for the
borylation of heteroarenes was investigated and compared to previously reported (1-TMP-2-BH2-
C6H4)2 (1; TMP = tetramethylpiperidyl) and (1-NMe2-2-BH2-C6H4)2 (4; NMe2 = dimethylamino).
It was shown that 2 and 3 are more active catalysts for the borylation of heteroarenes than the
bulkier analogue 1. Kinetic studies and DFT calculations were performed with 1 and 2 to ascertain
the influence of the amino group of this FLP-catalyzed transformation. The C-H activation step
was found to be more facile with smaller amines at the expense of a more difficult dissociation of
the dimeric species. The bench-stable fluoroborate salts of all catalysts (1F-4F) have been
synthesized and tested for the borylation reaction. The new precatalysts 2F and 3F are showing
higher reaction rates and yields for multi-gram scale syntheses
Catalytic (de)hydrogenation promoted by non-precious metals – Co, Fe and Mn: recent advances in an emerging field
ChemInform Abstract: NHC-Carbene Cyclopentadienyl Iron Based Catalyst for a General and Efficient Hydrosilylation of Imines.
ChemInform Abstract: Palladium(II)-Catalyzed ortho-C-H Arylation/Alkylation of N-Benzoyl α-Amino Ester Derivatives.
ChemInform Abstract: Potassium tert-Butoxide Mediated O-Arylation of N-Hydroxyphthalimide and Oximes with Diaryliodonium Salts.
ChemInform Abstract: Iron Dihydride Complex as the Pre-Catalyst for Efficient Hydrosilylation of Aldehydes and Ketones under Visible Light Activation.
ChemInform Abstract: Chelation-Assisted Nickel-Catalyzed Oxidative Annulation via Double C-H Activation/Alkyne Insertion Reaction.
Réaction d'hydrosilylation catalysées par des complexes bien définis du fer
Ce travail de recherche est consacré à la réduction des composés carbonylés tels que les aldéhydes, cétones, imines, esters et acides carboxyliques catalysée par des complexes bien définis du fer. La première partie de ce travail porte sur l'utilisation du système Fe(dppe) (H) (1mol %) / NaB(OEt)4 (1mol %) comme catalyseur efficace pour l'hydrosilylation des aldéhydes et cétones avec le PHMS sous activation lumineuse. Dans une seconde partie, une famille de complexes du type [CpFe(CO) PR ]X et CpFe(CO)(X)PR (PR = PPh et PCy ) a été développée et ces complexes se sont révélés être des catalyseurs actifs pour la réduction des aldéhydes, cétones et esters en alcools dans des conditions sans solvant et sous irradiation lumineuse en présence d'hydrosilanes. D'autre part, les complexes de type {[CpFe(CO) [Ph PCH Py-( P ou P,N)]}X sont efficaces pour l'amination réductrice d'arylaldehydes par hydrosilylation. Nous avons également montré dans la troisième partie du travail que les complexes demi-sandwich [CpFe(CO) (IMes)]I étaient d'excellents catalyseurs pour l'hydrosilylation des aldimines et kétimines en amines. Dans une dernière partie de ce travail, l'utilisation de complexes de fer(0) a permis de réduire sélectivement les acides carboxyliques en alcools avec Fe(COD)(CO) comme catalyseur en présence de PhSiH3 comme source d'hydrure sous irradiation UV ou en aldéhydes avec le catalyseur Fe(tPBO)(CO)3 en présence de TMDS comme agent réducteur à 50 C.This research work deals with the reduction of carbonyl compounds such as aldehydes, ketones, imines, esters and carboxylic acids via hydrosilylation using well-defined iron complexes. First of all, the couple Fe(dppe) (H) (1mol %) / NaB(OEt)4 (1mol %) showed to be an efficient catalytic system for the reduction of aldehydes and ketones with PMHS under visible light irradiation. On the other hand, [CpFe(CO) PR ]X and CpFe(CO)(X)PR type complexes (PR = PPh et PCy ) were good catalysts for the reduction of aldehydes, ketones and esters leading to alcohols in solvent-free conditions under visible light irradiation. {[CpFe(CO) [Ph PCH Py-( P ou P,N)]}X type complexes were effective catalysts for the reductive amination of benzaldehyde derivatives via hydrosilylation. In a third part, we have shown that the piano-stool complex [CpFe(CO) (IMes)]I was an excellent catalyst for the direct hydrosilylation of aldimines and ketimines to amines. Finally, in a fourth part, iron(0)-carbonyl complexes could reduce in a specific way free carboxylic acids to alcohols using PhSiH3 as the hydride source and Fe(COD)(CO)3 as the catalyst under UV-irradiation at r.t. or to aldehydes using TMDS as the reducing agent and Fe(tPBO)(CO)3 as the catalyst at 50 C.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF
NHC-carbene cyclopentadienyl iron based catalyst for a general and efficient hydrosilylation of imines.
International audienceA general and efficient hydrosilylation of imines catalysed by a well defined NHC-carbene cyclopentadienyl iron complex has been developed. Both aldimines and ketimines are converted to the corresponding amines under mild conditions, and under visible light activation
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