Aluminium‐Catalyzed C(sp)−H Borylation of Alkynes

Willcox, Dominic R.; Rosa, Daniel M. De; Howley, Jack; Levy, Abigail; Steven, Alan; Nichol, Gary S.; Morrison, Carole A.; Cowley, Michael J.; Thomas, Stephen P.

doi:10.1002/ange.202106216

Cited by 4 publications

(2 citation statements)

References 51 publications

(22 reference statements)

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“…Using an ambiphilic aluminium precatalyst, (Me 2 N)C 6 H 4 AlMe 2 , Thomas et al were able to shut down hydroalumination by the alane and catalyse the C-H borylation of terminal alkynes with HBpin (Scheme 21) [96]. Through kinetic analysis, it was found that the rate of the alkynyl-Bpin product formation was fastest during catalyst activation, rather than during catalysis, leading to an in-depth investigation of catalyst activation using variable time normalisation analysis (VTNA) and kinetic isotope effects.…”

Section: Aluminium Catalysismentioning

confidence: 99%

Group 13 exchange and transborylation in catalysis

Willcox¹,

Thomas²

2023

Beilstein J. Org. Chem.

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Catalysis is dominated by the use of rare and potentially toxic transition metals. The main group offers a potentially sustainable alternative for catalysis, due to the generally higher abundance and lower toxicity of these elements. Group 13 elements have a rich catalogue of stoichiometric addition reactions to unsaturated bonds but cannot undergo the redox chemistry which underpins transition-metal catalysis. Group 13 exchange reactions transfer one or more groups from one group 13 element to another, through σ-bond metathesis; where boron is both of the group 13 elements, this is termed transborylation. These redox-neutral processes are increasingly being used to render traditionally stoichiometric group 13-mediated processes catalytic and develop new catalytic processes, examples of which are the focus of this review.

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Section: Aluminium Catalysismentioning

confidence: 99%

Group 13 exchange and transborylation in catalysis

Willcox¹,

Thomas²

2023

Beilstein J. Org. Chem.

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“…9 Cowley and Thomas and co-workers recently reported an interesting application of an organoaluminium hydride catalyst for this dehydrogenative boration reaction. 10 Meanwhile, the 1,1-diboration of terminal alkynes could be promoted by Chirik's Co-catalyst, 11 Engle's Cu-catalyst 12 or Ingleson's Zn-catalyst 13 systems. If the terminal alkynes were in conjugation with an electron-withdrawing moiety, the reaction could also be promoted by Brønsted bases.…”

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confidence: 99%

A Universal Organocatalyst for Selective Mono-, Di- and Tri-Boration of Terminal Alkynes

Doan

Nguyên

2023

Preprint

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Multiboronate compounds are valuable synthetic building blocks for the construction of complex organic architectures via cross-coupling chemistry at C-B bonds. Hence, there has been a tremendous amount of work in the past decades to develop practical multiboration reactions. Many of developed methods start from alkynes, the most versatile synthetic precursors for multiboronates, and use transition-metal complexes as catalysts. However, several drawbacks such as low efficiency, poor selectivity and narrow substrate and catalyst scopes remain major challenges to be ad-dressed in this research area. Herein, we report the development of a universal organocatalytic system to promote the mono-, di- and tri-boration of terminal alkynes in highly efficient and selective manner. The reaction outcomes can be manipulated at will by varying catalyst loading, reagent stoichiometry and reaction time.

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Lithium Aluminium Hydride and Metallic Iron: A Powerful Team in Alkene and Arene Hydrogenation Catalysis

et al. 2023

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Alkenes that normally do not react with LiAlH4 (3‐hexene, cyclohexene, 1‐Me‐cyclohexene), can be reduced to the corresponding alkanes by a mixture of LiAlH4 and Fe0 (the iron was activated by Metal‐Vapour‐Synthesis). This alkene‐to‐alkane conversion with a stoichiometric quantity of LiAlH4/Fe0 does not need quenching with water or acids, implying that both H's originate from LiAlH4. The LiAlH4/Fe0 combination is also a remarkably potent cooperative catalyst for hydrogenation of multi‐substituted alkenes and benzene or toluene. An induction period of circa two hours and the minimally required temperature of 120 °C, suggests that the actual catalyst is a combination of Fe0 and the decomposition product of LiAlH4 (LiH and Al0). A thermally pre‐activated LiAlH4/Fe0 catalyst did not need an induction time and is also active at room temperature and 1 bar H2. A combination of AliBu3 and Fe0 is an even more active hydrogenation catalyst. Without pre‐activation, tetra‐substituted alkenes like Me2C=CMe2 and toluene could be fully hydrogenated.

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Aluminium‐Catalyzed C(sp)−H Borylation of Alkynes

Cited by 4 publications

References 51 publications

Group 13 exchange and transborylation in catalysis

Group 13 exchange and transborylation in catalysis

A Universal Organocatalyst for Selective Mono-, Di- and Tri-Boration of Terminal Alkynes

Lithium Aluminium Hydride and Metallic Iron: A Powerful Team in Alkene and Arene Hydrogenation Catalysis

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