A Heterogeneous Iridium Catalyst for the Hydroboration of Pyridines DOI

Jessica Rodriguez,

Matthew P. Conley

Organic Letters, Journal Year: 2022, Volume and Issue: 24(25), P. 4680 - 4683

Published: June 16, 2022

Sulfated zirconium oxide (SZO) capped with silylium-like ions reacts (cod)Ir(py)Cl (cod = 1,5-cyclooctadiene; py pyridine) to form [Ir(cod)py][SZO] (1) and Me3SiCl. 1 can also be formed in reactions of phosphonium functionalized SZO [Ir(cod)(OSi(OtBu)3]2, which forms [Ir(cod)P(tBu)2Ph][SZO] (2), followed by reaction pyridine 1. FTIR 15N{1H} MAS NMR spectroscopy are consistent coordination an electrophilic iridium. is moderately active the dearomative hydroboration pyridine. The primary product this 1,2-dihydropyridine, converts 1,4-dihydropyridine at long times. catalyzes a variety substituted pyridines reactive toward pyrazines N-methylimidazole.

Language: Английский

A N‐Heterocyclic Carbene‐Supported Zinc Catalyst for the 1,2‐Regioselective Hydroboration of N‐Heteroarenes DOI

Sumana Mondal,

Tejender Singh,

Sudip Baguli

et al.

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 29(38)

Published: April 20, 2023

A fluorenyl-tethered N-heterocyclic carbene LH (LH=[(Flu)H-(CH2 )2 -NHCDipp ]) and its monoanionic version L- are explored in complexation with zinc towards the hydroboration of N-heteroarenes, carbonyl, ester, amide, nitrile under ambient condition. The N-heteroarenes exhibit high 1,2-regioselectivity which is justified by computational analyses. relative rates differently p-substituted (electron donating vs. withdrawing) pyridines also addressed. monodentate offers a better catalytic activity than chelating for steric reasons despite both giving three-coordinate complexes. mechanism involves Zn-H species at heart these processes trapped Ph2 CO. Computational studies suggest that barrier to form hydride complex comparable required following transfer pyridine.

Language: Английский

Citations

13
Iron-Catalyzed Selective Hydroboration of CO2 by Cooperative B–H Bond Activation DOI

Hongjie Gao,

Jiong Jia,

Chen‐Ho Tung

et al.

Organometallics, Journal Year: 2023, Volume and Issue: 42(10), P. 944 - 951

Published: May 9, 2023

We report a novel iron(II) complex supported by an anionic phosphanyl-iminopyridinate ligand, Cp*Fe(Cy2PN═C5H4N) (1), which shows remarkable catalytic activity in the selective hydroboration of CO2 with HBpin, producing boryl formate turnover frequency (TOF) ∼1176 h–1 at room temperature. This catalysis involves cooperative metal–ligand reactivity for H–B bond activation, affording key Fe(II)–H intermediate, Cp*FeH(Cy2PN(Bpin)C5H4N) (2), that binds Bpin moiety non-coordinated amino site. The very fast and formoxy production can be conveniently coupled to N-formylation amines, delivers variety formamides. In addition, reduction CH3OBpin stage was also achieved 1 HBpin under N2.

Language: Английский

Citations

13
Bicyclic (alkyl)(amino)carbene (BICAAC) as a metal-free catalyst for reduction of nitriles to amines DOI
Nimisha Gautam, Ratan Logdi,

P Sreejyothi

et al.

Chemical Communications, Journal Year: 2022, Volume and Issue: 58(18), P. 3047 - 3050

Published: Jan. 1, 2022

Bicyclic (alkyl)(amino)carbene (BICAAC) is introduced as a metal-free catalyst for the reduction of various nitriles to corresponding amine hydrochloride salts in presence pinacolborane. Mechanistic investigations combining experiments and DFT calculations suggest B-H addition carbene center, which acts carrier hydride source.

Language: Английский

Citations

19
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
Cobalt-catalyzed double hydroboration of pyridines DOI Creative Commons
Finn Höeg,

Lea Luxenberger,

Andrey Fedulin

et al.

Chemical Science, Journal Year: 2024, Volume and Issue: 15(14), P. 5201 - 5210

Published: Jan. 1, 2024

Cobalt(ii) complexes were prepared from a modular phosphinopyridonate platform and applied to the hydroboration of pyridines. The synthetically useful, yet challenging, double toward tetrahydropyridine derivatives was successfully performed with high activity regiocontrol. This new method enabled direct synthesis N-heterocyclic allylic boronates commercial pyridines pinacolborane (HBpin). One-pot acetylation afforded bench-stable borylated N-acetyl tetrahydropyridines in good yields. synthetic utility this procedure demonstrated by gram-scale hydroboration-acetylation sequence followed chemical diversification. Mechanistic experiments indicated metal-ligand cooperativity involving ligand-centered C-H activation intermediacy cobalt(iii) hydride species.

Language: Английский

Citations

3
Low-valent-tungsten catalysis enables hydroboration of esters and nitriles DOI
Heng Song, Yuting Xiao, Jingjing Wei

et al.

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(38), P. 5026 - 5029

Published: Jan. 1, 2024

In the research presented herein, low-valent-tungsten-catalyzed hydroboration of esters and nitriles was investigated.

Language: Английский

Citations

3
A Boron-Nitrogen Double Transborylation Strategy for Borane-Catalyzed Hydroboration of Nitriles DOI

Subham Pradhan,

Raman Vijaya Sankar,

Chidambaram Gunanathan

et al.

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(18), P. 12386 - 12396

Published: Aug. 31, 2022

Organoborane-catalyzed hydroboration of nitriles provides N,N-diborylamines, which act as efficient synthons for the synthesis primary amines and secondary amides. Known nitrile methods are dominated by metal catalysis. Simple metal-free using diborane [H-B-9-BBN]2 a catalyst pinacolborane turnover reagent is reported. The reaction monomeric H-B-9-BBN with leads to hydrido-bridged diborylimine intermediate; subsequent sequential double hydroboration-transborylation pathway involving B-N/B-H σ bond metathesis proposed.

Language: Английский

Citations

14
Reactivity of a Piano-Stool Iron Complex toward Boranes DOI

Qiuming Liang,

Hector A. Garcia Mayerstein, Datong Song

et al.

Organometallics, Journal Year: 2023, Volume and Issue: 42(9), P. 816 - 824

Published: April 21, 2023

The binding and activation of boranes by transition-metal compounds are relevant to catalytic hydroboration reactions. Herein, we report the stoichiometric reactivity a piano-stool iron complex toward series boranes, where joint action metal center ligand active site has been observed, as well activity this various N-heterocycles.

Language: Английский

Citations

8
Hydroboration of Terminal Alkenes and trans‐1,2‐Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex DOI
Stefan Weber, Daniel Zobernig, Berthold Stöger

et al.

Angewandte Chemie, Journal Year: 2021, Volume and Issue: 133(46), P. 24693 - 24697

Published: Aug. 26, 2021

A Mn

Language: Английский

Citations

16
Selective Cascading Hydroboration of N-Heteroarenes via Cobalt Catalysis DOI
Ruibin Wang, Dongwook Kim, Sehoon Park

et al.

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(5), P. 3582 - 3595

Published: Feb. 20, 2024

Selective cascading hydroelementation of N-heteroarenes represented by pyridines can provide diverse accesses to not only dihydro products but also tetrahydro and piperidines bearing an sp3 C–E bond (E = B, Si, etc.). Herein, we describe the Co-catalyzed hydroboration quinolines pyridines. A precatalyst Co(acac)2 with a P∧N ligand (R-Fc-PHOX; R tBu, Ph, or iPr) enabled stepwise HBpin (1 3 equiv) exclusively give 1,2-DHQ C4-borylated tetrahydroquinolines in high efficiency (TON up 2000/[Co] gram scale TOF 500/h). similar system using monodentate phosphine efficiently catalyzed regio- stereoselective double furnish range 1,3-diboryl-1,2,3,4-tetrahydropyridines, which were situ hydrogenated corresponding C–B β nitrogen atom. Experimental mechanistic studies on quinoline suggested insights as follows: (1) precursor active (P∧N)Co hydride species is (P∧N)Co(acac)2, involved catalyst initiation step induction period. (2) The first phase highly 1,2-selective. (3) C(sp3)–B formation second turnover-limiting overall catalytic process. (4) under kinetic differentiation.

Language: Английский

Citations

2