Heteroditopic Chelating NHC Ligand-Supported Co^III Complexes: Catalysts for the Reductive Functionalization of Carbon Dioxide under Ambient Conditions

Organometallics, Journal Year: 2023, Volume and Issue: 42(12), P. 1395 - 1403

Published: April 17, 2023

Synthesis and characterization of heteroditopic chelating NHC ligand-supported air stable CoIII–NHC complexes (1a–d), featuring variable triazole N-substituents thus, being structurally tunable, are reported. These were observed to be very effective catalysts for the reductive functionalization CO2 with aromatic amines using hydrosilane under ambient conditions (1 bar pressure room temperature) yield diverse N-formylated amines, importantly, catalytic activity was found reasonably tuned by N-substituents, which is probably due some electronic modulations, supported electrochemical analysis, rather than any considerable steric alterations as indicated percent buried volume calculation. Notably, corresponding generated in situ also equally effective. It worth mentioning that this first report on N-formylation less nucleophilic primary employing a homogeneous Co complex, best our knowledge. In addition, control experiments suggest protocol proceeds via hydride formoxysilane intermediate formation.

Language: Английский

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Hydrosilylation of Terminal Alkynes Catalyzed by an Air-Stable Manganese–NHC Complex

The Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 88(13), P. 8133 - 8149

Published: June 15, 2023

In recent years, catalysis with base metal manganese has received a significant amount of interest. Catalysis complexes having N-heterocyclic carbenes (NHCs) is relatively underdeveloped in comparison to the extensively investigated catalysts possessing pincer ligands (particularly phosphine-based ligands). Herein, we describe synthesis two imidazolium salts decorated picolyl arms (L1 and L2) as NHC precursors. Facile coordination L1 L2 MnBr(CO)5 presence resulted formation manganese(I)-NHC (1 2) an air-stable solid good isolated yield. Single-crystal X-ray analysis revealed structure cationic [Mn(CO)3(NHC)][PF6] tridentate N,C,N binding ligand facile fashion. Along few known manganese(I) complexes, these Mn(I)-NHC 1 2 were tested for hydrosilylation terminal alkynes. Complex was proved be effective catalyst alkynes selectivity toward less thermodynamically stable β-(Z)-vinylsilanes. This method provided regioselectivity (anti-Markovnikov addition) stereoselectivity (β-(Z)-product). Experimental evidence suggested that present pathway involved organometallic mechanism manganese(I)-silyl species possible reactive intermediate.

Language: Английский

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Cooperative Asymmetric Dual Catalysis Involving a Chiral N-Heterocyclic Carbene Organocatalyst and Palladium in an Annulation Reaction: Mechanism and Origin of Stereoselectivity

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(2), P. 1133 - 1148

Published: Jan. 3, 2023

The increasing number of examples on cooperative dual catalysis involving organocatalysts and transition metal catalysts indicate their wider acceptance utility in synthetic applications. In such reactions, the concurrent activation substrates is likely to present mechanistic complexities. one studies, designed for intermolecular annulation aimed at making a biologically important class benzazepines, chiral N-heterocyclic carbenes engage an enal form Breslow intermediate (nucleophilic partner) Pd(0) activates rac-vinyl benzoxazinanone as Pd-π-allyl (electrophile). Given current importance lack molecular insights origin high enantio-/diastereoselectivities cooperativity catalytic we have undertaken detailed computational investigation using density functional theory. kinetically most accessible from (S)- (R)-vinyl found be Cre Csi (where re si denote open prochiral faces through which nucleophile can add), respectively. An energetically favorable change configuration Cre, via PPh3-induced π–σ–π isomerization, suggests that enantioconvergent mechanism was responsible enrichment desired species. Ready availability higher energy state (TS) alternative nucleophilic addition ee (computed >99%, experimental 99%). Improved shape complementarity between electrophile preferred C–C bond formation TS well noncovalent interactions (C–H··· π, π···π, H-bonding) therein dictates diastereoselectivity. intramolecular C–N final annulated product turnover-determining TS. Molecular energetic features, obtained our computations, are concert with several observations, even beyond sense extent stereoselectivities.

Language: Английский

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New insight into multiple hydrogen-bond networks of functional organosilicas system for collaborative transformation of CO2 under mild conditions

Separation and Purification Technology, Journal Year: 2023, Volume and Issue: 317, P. 123937 - 123937

Published: April 26, 2023

Language: Английский

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Control over borrowing hydrogen and acceptorless dehydrogenative coupling process for the Co(iii)–NHC catalysed chemoselective alkylation and cyclisation of 1,2-phenylenediamine with alcohols

Catalysis Science & Technology, Journal Year: 2023, Volume and Issue: 13(24), P. 7172 - 7180

Published: Jan. 1, 2023

Chemoselective alkylation and cyclisation of 1,2-phenylenediamine with alcohols via control cobalt–NHC catalysed borrowing hydrogen acceptorless dehydrogenative coupling is achieved by tuning the triazole substituent NHC ligand system.

Language: Английский

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