Photoinduced Halogen-Atom Transfer by N-Heterocyclic Carbene-Ligated Boryl Radicals for C(sp3)–C(sp3) Bond Formation

Wan, Ting; Capaldo, Luca; Ravelli, Davide; Vitullo, Walter; Zwart, Felix J. de; Bruin, Bas de; Noël, Timothy

doi:10.1021/jacs.2c10444

Cited by 52 publications

(17 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on the above experimental results and literature precedents, 9 g – i ,21 a plausible reaction mechanism is proposed as outlined in Scheme 5d. Upon light irradiation, the excited TBADT abstracts a hydrogen of NHC–borane to give [W 10 O 32 ] 5− H + and the NHC-boryl radical.…”

Section: Resultsmentioning

confidence: 84%

Selective multifunctionalization ofN-heterocyclic carbene boranesviathe intermediacy of boron-centered radicals

Wang

Lin

et al. 2023

Chem. Sci.

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 84%

Selective multifunctionalization ofN-heterocyclic carbene boranesviathe intermediacy of boron-centered radicals

Wang

Lin

et al. 2023

Chem. Sci.

View full text Add to dashboard Cite

show abstract

“…In this study, we still used a photoinduced fashion but introduced a new type of noncovalent cage···π interaction to develop an innovative reaction mode aiming to achieve the straightforward and site-selective B–H functionalization of nido -carboranes. Thus, 9-mesityl-10-methylacridinium perchlorate (Mes-AcrClO 4 , PC1 ), an extensively utilized photocatalyst, was chosen as it contains an electron-deficient aromatic acridinium unit, which may meet the requirement to establish a cage···π interaction with an aromatic nido -carborane cage anion.…”

Section: Resultsmentioning

confidence: 99%

Photoinduced Selective B–H Activation of nido-Carboranes

Xu,

Zhang,

et al. 2024

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The development of new synthetic methods for B–H bond activation has been an important research area in boron cluster chemistry, which may provide opportunities to broaden the application scope of boron clusters. Herein, we present a new reaction strategy for the direct site-selective B–H functionalization of nido-carboranes initiated by photoinduced cage activation via a noncovalent cage···π interaction. As a result, the nido-carborane cage radical is generated through a single electron transfer from the 3D nido-carborane cage to a 2D photocatalyst upon irradiation with green light. The resulting transient nido-carborane cage radical could be directly probed by an advanced time-resolved EPR technique. In air, the subsequent transformations of the active nido-carborane cage radical have led to efficient and selective B–N, B–S, and B–Se couplings in the presence of N-heterocycles, imines, thioethers, thioamides, and selenium ethers. This protocol also facilitates both the late-stage modification of drugs and the synthesis of nido-carborane-based drug candidates for boron neutron capture therapy (BNCT).

show abstract

“…Optimization studies were performed on the model cross-coupling reaction of p-methoxyphenyl cyclopropanol 1 a with electrophilic benzylidene malononitrile 2 a under ultraviolet light (370 nm) irradiation (Table 1; see also Table S1 in the Supporting Information for additional data). The experiments were carried out in a 3D printed reactor designed by the Noёl group [55] and equipped with a Kessil lamp (43 W at 100% light intensity). Previously reported conditions [44,49] (2 mol% TBADT in acetonitrile solution) were employed in the initial experiment (entry 1) which delivered ketone 3 aa in 84% yield after 3 h of irradiation.…”

Section: Resultsmentioning

confidence: 99%

Ring‐Opening Coupling Reaction of Cyclopropanols with Electrophilic Alkenes Enabled by Decatungstate as Photoredox Catalyst

Krech,

Yakimchyk,

Jarg

et al. 2023

Adv Synth Catal

View full text Add to dashboard Cite

We introduce a methodology for the photocatalytic generation of β‐ketoalkyl radicals from tertiary cyclopropanols, utilizing tetrabutylammonium decatungstate (TBADT) as a photoredox catalyst. The application is demonstrated by the synthesis of distantly functionalized ketones via the redox‐neutral addition of the cyclopropanol‐derived β‐ketoalkyl radicals to the double bond of electrophilic olefins. The transformation occurs under ambient temperature conditions and is suitable for coupling a wide range of cyclopropanol and alkene substrates. This was demonstrated by the preparation of 33 ketone products with 35–92% yield. The method's preparative robustness has been validated through upscaled preparations conducted under continuous flow conditions. Mechanistic investigations support the role of TBADT as a photoredox catalyst, which facilitates the single electron oxidation of cyclopropanols, followed by the electron transfer from the reduced form of decatungstate to the electrophilic double bond of alkene. Moreover, we found that electron‐rich aromatic cyclopropanols and electron‐deficient olefins form photoactive electron donor‐acceptor (EDA) complexes. This property allows the reaction to proceed under UV light irradiation via the photoinduced charge transfer in the absence of the photocatalyst.

show abstract

Photoinduced Halogen-Atom Transfer by N-Heterocyclic Carbene-Ligated Boryl Radicals for C(sp³)–C(sp³) Bond Formation

Cited by 52 publications

References 72 publications

Selective multifunctionalization ofN-heterocyclic carbene boranesviathe intermediacy of boron-centered radicals

Selective multifunctionalization ofN-heterocyclic carbene boranesviathe intermediacy of boron-centered radicals

Photoinduced Selective B–H Activation of nido-Carboranes

Ring‐Opening Coupling Reaction of Cyclopropanols with Electrophilic Alkenes Enabled by Decatungstate as Photoredox Catalyst

Contact Info

Product

Resources

About