Copper‐Catalyzed Boroaminomethylation of Olefins to γ‐Boryl Amines with CO as C1 Source DOI
Fu‐Peng Wu, Hui‐Qing Geng, Xiao‐Feng Wu

et al.

Angewandte Chemie, Journal Year: 2022, Volume and Issue: 134(46)

Published: Sept. 24, 2022

Abstract Boroaminomethylation of olefins is an efficient process to convert hydrocarbons directly into boron‐, nitrogen‐containing molecules. Such chemicals are a good handle for obtaining more complexed amine derivatives through the various transformations organoboron. However, using simple and easily available CO as C1 feedstock achieve boroaminomethylation still elusive. Here we report copper‐catalyzed with source via mechanism carbene insertion N−H bond. This method affords valuable γ ‐boryl amines from four inexpensive readily chemicals. The wide synthetic demonstrates their utility. Notably, 13 C labeling studies revealed that −CH 2 ‐building block was derived one molecule CO.

Language: Английский

Manganese-Catalyzed Dehydrogenative Silylation of Alkenes Following Two Parallel Inner-Sphere Pathways DOI Creative Commons
Stefan Weber,

Manuel Glavic,

Berthold Stöger

et al.

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(42), P. 17825 - 17832

Published: Oct. 13, 2021

We report on an additive-free Mn(I)-catalyzed dehydrogenative silylation of terminal alkenes. The most active precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. catalytic process initiated by migratory insertion a CO ligand into Mn–alkyl bond to yield acyl intermediate which undergoes rapid Si–H cleavage silane HSiR3 forming 16e– silyl catalyst [Mn(dippe)(CO)2(SiR3)] together with liberated butanal. A broad variety aromatic and aliphatic alkenes was efficiently selectively converted E-vinylsilanes allylsilanes, respectively, at room temperature. Mechanistic insights are provided based experimental data DFT calculations revealing that two parallel reaction pathways operative: acceptorless pathway involving dihydrogen release requiring alkene as sacrificial hydrogen acceptor.

Language: Английский

Citations

47
E-Selective Manganese-Catalyzed Semihydrogenation of Alkynes with H2 Directly Employed or In Situ-Generated DOI Creative Commons
Ronald A. Farrar‐Tobar, Stefan Weber, Zita Csendes

et al.

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(4), P. 2253 - 2260

Published: Jan. 31, 2022

Selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst fac-[Mn(dippe)(CO)3(CH2CH2CH3)] (dippe = 1,2-bis(di-iso-propylphosphino)ethane) as a precatalyst is described. The required hydrogen gas either directly employed or in situ-generated upon alcoholysis KBH4 methanol. A series aryl-aryl, aryl-alkyl, alkyl-alkyl, and terminal was readily hydrogenated to yield E-alkenes good excellent isolated yields. reaction proceeds at 60 °C for 60-90 loadings 0.5-2 mol %. implemented protocol tolerates variety electron-donating electron-withdrawing functional groups, including halides, phenols, nitriles, unprotected amines, heterocycles. can be upscaled gram scale. Mechanistic investigations, deuterium-labeling studies density theory (DFT) calculations, were undertaken provide reasonable mechanism, showing that initially formed Z-isomer undergoes fast isomerization afford thermodynamically more stable E-isomer.

Language: Английский

Citations

37
Manganese Alkyl Carbonyl Complexes: From Iconic Stoichiometric Textbook Reactions to Catalytic Applications DOI Creative Commons
Stefan Weber, Karl Kirchner

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(18), P. 2740 - 2751

Published: Sept. 8, 2022

ConspectusThe activation of weakly polarized bonds represents a challenging, yet highly valuable process. In this context, precious metal catalysts have been used as reliable compounds for the rather inert last several decades. Nevertheless, base-metal complexes including cobalt, iron, or nickel are currently promising candidates substitution noble metals in order to develop more sustainable processes. past few years, manganese(I)-based were heavily employed efficient (de)hydrogenation reactions. However, vast majority these operate via metal–ligand bifunctionality already well implemented decades ago. Although high reactivity can be achieved various reactions, concept is often not applicable certain transformations due outer-sphere mechanisms. Account, we outline potential alkylated Mn(I)-carbonyl nonpolar and moderately polar E–H (E = H, B, C, Si) disclose our successful approach utilization field homogeneous catalysis. This involves rational design manganese hydrogenation reactions involving ketones, nitriles, carbon dioxide, alkynes. addition that, reduction alkenes by dihydrogen could series well-defined which was possible before. Furthermore, elucidate Mn-based hydrofunctionalization carbon–carbon multiple bonds. Our investigations unveiled novel insights into reaction pathways dehydrogenative silylation trans-1,2-diboration terminal alkynes, reported transition metals. Due catalyst design, under mild conditions. Delightfully, all bench-stable compounds. We took advantage fact that Mn(I) alkyl known undergo migratory insertion group CO ligand, yielding an unsaturated acyl intermediate. Hydrogen atom abstraction ligand then paves way active species variety catalytic proceed inner-sphere textbook well-known decades, application still its infancy. A brief historical overview manganese(I)–carbonyl provided, covering synthesis especially iconic stoichiometric transformations, e.g., carbonylation, intensively examined Calderazzo, Moss, others. An future applications defined will given, may inspire researchers development (base-)metal catalysts.

Language: Английский

Citations

32
Homogeneous Manganese-Catalyzed Hydrofunctionalizations of Alkenes and Alkynes: Catalytic and Mechanistic Tendencies DOI Creative Commons
Antonio Torres-Calis, Juventino J. Garcı́a

ACS Omega, Journal Year: 2022, Volume and Issue: 7(42), P. 37008 - 37038

Published: Oct. 11, 2022

In recent years, many manganese-based homogeneous catalytic precursors have been developed as powerful alternatives in organic synthesis. Among these, the hydrofunctionalizations of unsaturated C–C bonds correspond to outstanding ways afford compounds with more versatile functional groups, which are commonly used building blocks production fine chemicals and feedstock for industrial field. Herein, we present an account Mn-catalyzed alkenes alkynes main objective finding mechanistic tendencies that could serve a platform works come.

Language: Английский

Citations

28
Manganese catalysed reduction of nitriles with amine boranes DOI Creative Commons
Stefan Weber, Ines Blaha, Karl Kirchner

et al.

Catalysis Science & Technology, Journal Year: 2024, Volume and Issue: 14(17), P. 4843 - 4847

Published: Jan. 1, 2024

The room temperature reduction of various nitriles using amine boranes catalysed by a manganese( i ) alkyl complex is described. Based on experimental findings, plausible mechanistic scenario presented.

Language: Английский

Citations

4
Base- and Additive-Free Carbon Dioxide Hydroboration to Methoxyboranes Catalyzed by Non-Pincer-Type Mn(I) Complexes DOI Creative Commons
Sylwia Kostera, Stefan Weber, Ines Blaha

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(8), P. 5236 - 5244

Published: March 31, 2023

Well-defined, bench stable Mn(I) non-pincer-type complexes were tested as earth-abundant transition metal catalysts for the selective reduction of CO2 to boryl-protected MeOH in presence pinacolborane (HBpin). Essentially, quantitative yields obtained under mild reaction conditions (1 bar CO2, 60 °C), without need any base or additives, alkylcarbonyl bis(phosphine) fac-[Mn(CH2CH2CH3)(dippe)(CO)3] [Mn1, dippe = 1,2-bis(diisopropylphosphino)ethane] and [Mn(dippe)(CO)2{(μ-H)2(Bpin)}] (Mn4), that is by bench-stable precatalyst Mn1 with HBpin via elimination butanal. Preliminary mechanistic details a combination NMR experiments monitoring catalytic reactions.

Language: Английский

Citations

10
Monomeric Magnesium Catalyzed Alkene and Alkyne Hydroboration DOI
Rohit Kumar, Sayan Dutta, Vishal Sharma

et al.

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 28(56)

Published: July 21, 2022

Abstract In this work, two monomeric magnesium alkyl complexes ( 1 and 2 ) were prepared using bis(phosphino)carbazole framework among them has been used as a catalyst for hydroboration of alkenes alkynes with pinacolborane (HBpin). A broad variety aromatic aliphatic efficiently reduced. Anti‐Markovnikov regioselective was achieved, which confirmed by deuterium‐labelling experiments. The work represents the first example use in homogeneous catalytic alkene substrate scope. Experimental mechanistic investigations DFT calculations provided insights into reaction mechanism. Finally, protocol extended to terpenes.

Language: Английский

Citations

15
Selective Transfer Semihydrogenation of Alkynes Catalyzed by an Iron PCP Pincer Alkyl Complex DOI Creative Commons
Heiko Schratzberger, Berthold Stöger, Luı́s F. Veiros

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(21), P. 14012 - 14022

Published: Oct. 17, 2023

Two bench-stable Fe(II) alkyl complexes [Fe(κ3PCP-PCP-iPr)(CO)2(R)] (R = CH2CH2CH3, CH3) were obtained by the treatment of [Fe(κ3PCP-PCP-iPr)(CO)2(H)] with NaNH2 and subsequent addition CH3CH2CH2Br CH3I, respectively. The reaction proceeds via anionic Fe(0) intermediate Na[Fe(κ3PCP-PCP-iPr)(CO)2]. catalytic performance both was investigated for transfer hydrogenation terminal internal alkynes utilizing PhSiH3 iPrOH as a hydrogen source. Precatalyst activation is initiated migration ligand to carbonyl C atom an adjacent CO ligand. In agreement previous findings, rate follows order nPr > Me. Accordingly, [Fe(κ3PCP-PCP-iPr)(CO)2(CH2CH2CH3)] more active catalyst. takes place at 25 °C catalyst loading 0.5 mol%. There no overhydrogenation, in case alkynes, exclusively, Z-alkenes are formed. implemented protocol tolerates variety electron-donating electron-withdrawing functional groups including halides, nitriles, unprotected amines, heterocycles. Mechanistic investigations deuterium labeling studies DFT calculations undertaken provide reasonable mechanism.

Language: Английский

Citations

9
Tandem manganese catalysis for the chemo-, regio-, and stereoselective hydroboration of terminal alkynes: in situ precatalyst activation as a key to enhanced chemoselectivity DOI Creative Commons
Victor Duran Arroyo, Rebeca Arévalo

RSC Advances, Journal Year: 2024, Volume and Issue: 14(8), P. 5514 - 5523

Published: Jan. 1, 2024

The manganese( ii ) complex [Mn( iPr PNP)Cl 2 ] ( PNP = 2,6-bis(diisopropylphosphinomethyl)pyridine) was found to catalyze the stereo- and regioselective hydroboration of terminal alkynes employing HBPin (pinacolborane).

Language: Английский

Citations

3
Alkene Isomerization Catalyzed by a Mn(I) Bisphosphine Borohydride Complex DOI Creative Commons
Ines Blaha, Stefan Weber,

Robin Dülger

et al.

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(17), P. 13174 - 13180

Published: Aug. 17, 2024

An additive-free manganese-catalyzed isomerization of terminal alkenes to internal is described. This reaction implementing an inexpensive nonprecious metal catalyst. The most efficient catalyst the borohydride complex cis-[Mn(dippe)(CO)2(κ2-BH4)]. operates at room temperature, with a loading 2.5 mol %. A variety effectively and selectively transformed into respective E-alkenes. Preliminary results show chain-walking elevated temperature. Mechanistic studies were carried out, including stoichiometric reactions in situ NMR analysis. These experiments are flanked by computational studies. Based on these, catalytic process initiated liberation "BH3" as THF adduct. double bond insertion M-H species, leading alkyl intermediate, followed β-hydride elimination opposite position afford product.

Language: Английский

Citations

2