C–H borylation: a tool for molecular diversification

Guria, Saikat; Hassan, Mirja Md Mahamudul; Chattopadhyay, Buddhadeb

doi:10.1039/d3qo01931d

“…Among the various methods, transition-metal-catalyzed C–H borylation stands out 1–6 due to its versatility in converting C–B bonds into C–N, C–D, C–O, C–X, and C–C bonds. 7 In addition, organoboron compounds are widely used in biomarker discovery, 8,9 chemical sensing, 10 bioprobe development, 11 and molecular imaging. 12 Moreover, advancements in boron chemistry have propelled the use of boron-containing compounds in drug discovery, 13,14 exemplified by bortezomib, 15 the first FDA-approved boron-containing drug for treating multiple myeloma.…”

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confidence: 99%

Iridium-catalyzed meta-selective C–H borylation of phenol derivatives

Ju,

Gao,

Liang

et al. 2024

Org. Chem. Front.

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Transition Metal‐Free Catalytic C−H Zincation and Alumination

Kumar Bisai,

Łosiewicz,

Sotorrios

et al. 2024

Angewandte Chemie

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C−H metalation is the most efficient method to prepare aryl–zinc and –aluminium complexes that are ubiquitous nucleophiles. Virtually all C–H metalation routes to form Al/Zn organometallics require stoichiometric, strong Brønsted bases with no base‐catalyzed reactions reported. Herein we present a catalytic in amine/ammonium salt (Et3N/[(Et3N)H]+) C–H metalation process to form aryl‐zinc and aryl‐aluminium complexes. Key to this approach is coupling an endergonic C–H metalation step with a sufficiently exergonic dehydrocoupling step between the ammonium salt by‐product of C–H metalation ([(Et3N)H]+) and a Zn–H or Al–Me containing complex. This step, forming H2/MeH, makes the overall cycle exergonic while generating more of the reactive metal electrophile. Mechanistic studies supported by DFT calculations revealed metal‐specific dehydrocoupling pathways, with the divergent reactivity due to the different metal valency (which impacts the accessibility of amine‐free cationic metal complexes) and steric environment. Notably, dehydrocoupling in the zinc system proceeds through a ligand‐mediated pathway involving protonation of the b‐diketiminate Cg position. Given this process is applicable to two disparate metals (Zn and Al), other main group metals and ligand sets are expected to be amenable to this transition metal‐free, catalytic C−H metalation.

show abstract

Transition Metal‐Free Catalytic C−H Zincation and Alumination

Kumar Bisai,

Łosiewicz,

Sotorrios

et al. 2024

Angew Chem Int Ed

0

View full text Add to dashboard Cite

C−H metalation is the most efficient method to prepare aryl–zinc and –aluminium complexes that are ubiquitous nucleophiles. Virtually all C–H metalation routes to form Al/Zn organometallics require stoichiometric, strong Brønsted bases with no base‐catalyzed reactions reported. Herein we present a catalytic in amine/ammonium salt (Et3N/[(Et3N)H]+) C–H metalation process to form aryl‐zinc and aryl‐aluminium complexes. Key to this approach is coupling an endergonic C–H metalation step with a sufficiently exergonic dehydrocoupling step between the ammonium salt by‐product of C–H metalation ([(Et3N)H]+) and a Zn–H or Al–Me containing complex. This step, forming H2/MeH, makes the overall cycle exergonic while generating more of the reactive metal electrophile. Mechanistic studies supported by DFT calculations revealed metal‐specific dehydrocoupling pathways, with the divergent reactivity due to the different metal valency (which impacts the accessibility of amine‐free cationic metal complexes) and steric environment. Notably, dehydrocoupling in the zinc system proceeds through a ligand‐mediated pathway involving protonation of the b‐diketiminate Cg position. Given this process is applicable to two disparate metals (Zn and Al), other main group metals and ligand sets are expected to be amenable to this transition metal‐free, catalytic C−H metalation.

show abstract

C–H borylation: a tool for molecular diversification

Abstract: Iridium-catalyzed C-H activation and borylation witnessed as a powerful synthetic tool in the past few decades because of the widespread applicability and versatility of organoboron compounds. Nowadays, this reaction has...

Cited by 8 publications

References 152 publications

Iridium-catalyzed meta-selective C–H borylation of phenol derivatives

Iridium-catalyzed meta-selective C–H borylation of phenol derivatives

Transition Metal‐Free Catalytic C−H Zincation and Alumination

Transition Metal‐Free Catalytic C−H Zincation and Alumination

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