Disarming the alkoxide trap to access a practical FeCl₃ system for borrowing-hydrogen N-alkylation

Abstract

Borrowing hydrogen N-alkylation is one of the most valuable transformations in organic synthesis with high selectivity and atomic economy. The general non-noble metal catalysts for borrowing hydrogen usually have limitations...

Surmounting Alkoxide Trap Strategy: N-Heterocyclic Carbene Chromium(0)-Catalyzed C-Alkylation between Alcohols

“…On the basis of previous studies, ,, alcohol dehydrogenations to generate active metal hydride species are influenced by the alkoxide trap effect for the metal-alkoxide intermediate . To evaluate the catalytic performance in C -alkylation with alcohols via BH/HA, the thermodynamics of the metal-alkoxide intermediate and the kinetics of the alcohol dehydrogenation step would be critical points to be investigated.…”

“…In the case of 2a , a lower R 2 was obtained. It is probably owing to the relatively small changes in the concentration of the product . The results of reaction orders indicate that one molecule of 1a and one metal center are involved in the RDS of the reaction.…”

Development and mechanistic investigation of the dehydrogenation of alcohols with an iron(iii) salen catalyst

“…11 Recently, FeCl 3 has also been reduced in the presence of N-heterocyclic carbene ligands to iron( ii ) complexes, which can mediate the alkylation of amines with alcohols. 12…”

“…11 Recently, FeCl 3 has also been reduced in the presence of N-heterocyclic carbene ligands to iron(II) complexes, which can mediate the alkylation of amines with alcohols. 12 The lack of well-defined iron(III) complexes for (de)hydrogenative transformations made us speculate whether iron(III) salen complexes would be able to serve as catalysts for these reactions. The idea is inspired from our recent discovery of a manganese(III) salen complex for catalyzing the acceptorless dehydrogenation of alcohols, which constituted the first example of a manganese(III) catalyst for this transformation.…”

Mechanistic insight into borrowing-hydrogenN-alkylation catalyzed by an MLC catalyst with dual proton-responsive sites

“…Nevertheless, the mechanisms associated with catalytic hydrogenation are very diverse. [25][26][27][28][29] For instance, the formation of hydrides can occur through either ligand-dissociated inner-sphere transfer or ligand-assisted outer-sphere transfer. Notably, imidazoline ligands of this catalyst possess two potential amido active sites after the pre-activation, the proximal α-amido group that coordinates to the Ru centre and the remote γ-amido group after the resonance of the CvN bond.…”