Construction of Benzocyclobutenes Enabled by Visible‐Light‐Induced Triplet Biradical Atom Transfer of Olefins

Liu, Jiaxin; Hao, Tonggang; Liu, Qian; Shi, Min; Wei, Yin

doi:10.1002/anie.202204515

Cited by 14 publications

(9 citation statements)

References 104 publications

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“…We investigated α‐methylstyrene substituted with fluorine ( 2′b ) and trifluoromethyl ( 2′c ), resulting in the construction of gem ‐cyclobutanes with all‐quaternary carbons ( 3 aj – ak ), in addition to the formation of the corresponding HAT products 4′b – c (Figure 3b). [17a,22d] Furthermore, substituted arylated‐ gem ‐diborylalkenes with fluorine ( 1 i ) and ( 1 g ) were also found to be suitable, leading to the formation of the desired products 3 al – am and 4′d – e (Figure 3b). Nevertheless, 1‐naphthalene gem ‐diborylalkene 1 c has proven to be effective in the formation of syn product 3 an in excellent diastereoselectivity (01 : 99) and 72 % yield (Figure 3b).…”

Section: Resultsmentioning

confidence: 96%

PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event

Hanania,

Eghbarieh,

Masarwa

2024

Angewandte Chemie

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While polyborylated alkenes are being recognized for their elevated status as highly valuable reagents in modern organic synthesis, allowing efficient access to a diverse array of transformations, including the formation of C–C and C–heteroatom bonds, their potential as energy‐transfer reactive groups has remained unexplored. Yet, this potential holds the key to generating elusive polyborylated biradical species, which can be captured by olefins, thereby leading to the construction of new highly‐borylated scaffolds. Herein, we report a designed energy‐transfer strategy for photosensitized [2+2]‐cycloadditions of poly‐borylated alkenes with various olefins enabling the regioselective synthesis of diverse poly‐borylated cyclobutane motifs, including the 1,1‐di‐, 1,1,2‐tri‐, and 1,1,2,2‐tetra‐borylated cyclobutanes. In fact, these compounds belong to a family that presently lacks efficient synthetic pathways. Interestingly, when α‐methylstyrene was used, the reaction involves an interesting 1,5‐hydrogen atom transfer. Mechanistic deuterium‐labeling studies have provided insight into the outcome of 1,5‐hydrogen atom transfer process. In addition, the polyborylated cyclobutanes are then demonstrated to be useful in selective oxidation processes resulting in the formation of cyclobutanones and γ‐lactones.

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Section: Resultsmentioning

confidence: 96%

PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event

Hanania,

Eghbarieh,

Masarwa

2024

Angewandte Chemie

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“…Iodoarene derivative 3a underwent halogen-lithium exchange with n-butyllithium, generating an aryllithium species which, upon reaction with DMF, yielded aldehyde 5a and upon addition to benzaldehyde, afforded alcohol 5b. 28 Furthermore, a copper-catalyzed cross-coupling of 3a with HPPh2 furnished the phosphine ligand 5c, 29 a compound previously difficult to obtain using conventional methods. Additionally, the Pd-catalyzed cross-coupling of 3a with B2pin2 proceeded smoothly, resulting in the formation of arylbronic ester 5d.…”

Section: Substrate Scope and Synthetic Utilitymentioning

confidence: 99%

Dual Ligand Enabled Pd-Catalyzed Ortho-Alkylation of Iodoarenes

Wang,

Jiao

2024

Preprint

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The synthesis of complex polysubstituted aromatic molecules from simple precursors is a central goal in organic chemistry. In this study, we developed an approach for the ortho-alkylation of iodoarenes utilizing a dual ligand catalytic system. By combining Pd/olefin ligand cooperative catalysis with bulky trialkylphosphine ligand-promoted C(sp2)-I reductive elimination, we have established an ortho-alkylative Catellani-type reaction with the aryl-iodine bond reconstruction as the final step, which opens new synthetic opportunities within the Catellani-type reactions. Through in-depth mechanistic investigations, we have isolated and characterized key organopalladium intermediates, revealing the synergistic interaction of the dual ligands in merging the Catellani-type process with C(sp2)-I reductive elimination. The present study showcases the unique advantages of Pd/olefin ligand catalysis and emphasizes the effectiveness of the dual ligand system in expanding the chemical space of the Catellani chemistry.

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“…Visible-light-mediated energy transfer (EnT) catalysis has emerged as an efficient and valuable alternative, enabling access to reactive triplet states and facilitating subsequent organic transformations. − Inspired by the remarkable progress in EnT catalysis, we reasoned that the EnT method may enable the activation of N -tosylhydrazone due to its inherent weak N–S bond strength. , With the release of sulfonyl groups and nitrogen, an in situ triplet-state carbene species should be formed and subsequently facilitate the generation of highly congested EWG-free cyclopropanes with 1,1-disubstituted alkenes. Considering this possibility, we undertook the challenge and designed an EnT-mediated σ-bond homolysis toward the activation of N -tosylhydrazones and the synthesis of highly congested cyclopropanes bearing contiguous all-carbon quaternary centers (Scheme D).…”

Section: Introductionmentioning

confidence: 99%

Visible-Light-Mediated Energy Transfer Enables Cyclopropanes Bearing Contiguous All-Carbon Quaternary Centers

Xia

Wang

et al. 2023

ACS Catal.

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Cyclopropanes bearing contiguous all-carbon quaternary centers continue to attract attention due to their bioactivities. However, methods to obtain cyclopropanes with contiguous all-carbon quaternary centers remain largely unexplored due to the high steric hindrance of these compounds. Herein, we report a visible-light-mediated energy-transfer (EnT) strategy to realize in situ donor/donor carbenes from readily available N-tosylhydrazones, facilitating the synthesis of highly congested EWG-free cyclopropanes. Through this approach, cyclopropanes are rapidly installed into complex bioactive molecules, fluorescent molecules, and other useful building blocks that are challenging to synthesize. Detailed mechanistic reactions and DFT studies clearly demonstrated the role of the photosensitizer, the formation of donor/donor carbenes, and the necessity of light and a base in the system.

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Construction of Benzocyclobutenes Enabled by Visible‐Light‐Induced Triplet Biradical Atom Transfer of Olefins

Cited by 14 publications

References 104 publications

PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event

PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event

Dual Ligand Enabled Pd-Catalyzed Ortho-Alkylation of Iodoarenes

Visible-Light-Mediated Energy Transfer Enables Cyclopropanes Bearing Contiguous All-Carbon Quaternary Centers

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