Transition-metal free C–C bond cleavage/borylation of cycloketone oxime esters

Zhang, Jinjiang; Duan, Xin‐Hua; Wu, Yong; Yang, Juncheng; Guo, Li‐Na

doi:10.1039/c8sc03315c

Cited by 127 publications

(43 citation statements)

References 97 publications

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“…Cycloalkyliminyl and cycloalkylaminyl radical involved ring‐opening reactions have attracted much attention in recent years . For example, the groups of Zard, Leonori, Xiao, and Guo have developed iminyl‐radical‐mediated ring‐opening of strained rings by using either oxime esters or ethers as the substrates (Scheme b). Meanwhile, the groups of Zheng– and Waser have independently reported ring‐opening reconstruction and functionalization of strained cyclopropylamines and cyclobutylamines.…”

Section: Methodsmentioning

confidence: 99%

Deconstructive Oxygenation of Unstrained Cycloalkanamines

et al. 2020

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A deconstructive oxygenation of unstrained primary cycloalkanamines has been developed for the first time using an auto‐oxidative aromatization promoted C(sp3)−C(sp3) bond cleavage strategy. This metal‐free method involves the substitution reaction of cycloalkanamines with hydrazonyl chlorides and subsequent auto‐oxidative annulation to in situ generate pre‐aromatics, followed by N‐radical‐promoted ring‐opening and further oxygenation by 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and m‐cholorperoxybenzoic acid (mCPBA). Consequently, a series of 1,2,4‐triazole‐containing acyclic carbonyl compounds were efficiently produced. This protocol features a one‐pot operation, mild reaction conditions, high regioselectivity and ring‐opening efficiency, broad substrate scope, and is compatible with alkaloids, osamines, and peptides, as well as steroids.

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Section: Methodsmentioning

confidence: 99%

Deconstructive Oxygenation of Unstrained Cycloalkanamines

et al. 2020

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“…A ringopening radical borylation of cycloketone oxime esters 18 under transition-metal-free conditions was achieved by the group of Guo (Scheme 50). 71 A series of boron sources, such as B 2 Pin 2 , B 2 Cat 2 and B 2 (OH) 4 were examined, with B 2 (OH) 4 giving the best results. Interestingly, B 2 (OH) 4 not only acts as the boron source, but also serves as an electron donor to form a B…”

Section: C-b Bond Formationmentioning

confidence: 99%

Iminyl-Radical-Triggered C–C Bond Cleavage of Cycloketone Oxime Derivatives: Generation of Distal Cyano-Substituted Alkyl Radicals and Their Functionalization

et al. 2020

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Alkyl nitriles are versatile building blocks in organic synthesis because the cyano group can be easily converted into other functional groups. Iminyl-radical-triggered C–C bond cleavage of cycloketone oxime derivatives provides a practical route to access distal cyano-substituted alkyl radicals, which has given chemists a new radical reaction platform for the synthesis of diverse alkyl nitriles. This review provides an overview of various types of radical cyanoalkylation via ring opening of cycloketone oxime derivatives.1 Introduction2 C–C Bond Formation2.1 Alkenes as Radical Acceptors2.2 Aromatic Rings as Radical Acceptors2.3 Organometallic Reagents as Radical Acceptors2.4 Cyanoalkyl-Radical-Triggered Cyclization Reactions2.5 Miscellaneous3 C–Heteroatom Bond Formation3.1 C–O Bond Formation3.2 C–N Bond Formation3.3 C–S Bond Formation3.4 C–Halogen Bond Formation3.5 C–B Bond Formation4 Conclusion

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“…In 2019, Guo and co‐workers achieved the borylation of cyclobutanone oxime esters 110 with B 2 (OH) 4 in DMAc ( N , N ‐dimethylacetamide) to construct C( sp 3 )−B bonds (Scheme 39). [51] Generally, a number of oxime esters bearing substitutes at C3‐position were well tolerated, where electron‐withdrawing groups on the aromatic ring of oxime esters were observed to give inferior yields. Additionally, secondary cyanoalkylated boronic esters were prepared by using B 2 Cat 2 as the boron source at 80 °C under the light irradiation.…”

Section: Dmac/b2(oh)4 or Dmac‐promoted Cross‐coupling Reactionsmentioning

confidence: 99%

Recent Developments in Radical Cross‐Coupling of Redox‐Active Cycloketone Oximes

2020

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Recent years have witnessed a renaissance of radical cross‐coupling of cycloketone oximes which served as active cyanoalkyl radical via ring fragmentation in various transformations. It provided an efficient and practical strategy to introduce cyanoalkyl groups into organic compounds without using toxic cyanide sources. In this review, a comprehensive overview of recent advances in the field of redox‐active cycloketone oximes‐based cross‐couplings were covered. This review was categorized into two broad parts: non‐photocatalyzed and photocatalyzed cross‐couplings according to the reaction conditions. Moreover, the two broad parts were further divided into several sub‐sections depending on the nature of the bond formation. Some representative examples along with reaction mechanisms were also discussed.

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Transition-metal free C–C bond cleavage/borylation of cycloketone oxime esters

Abstract: An efficient transition-metal free C–C bond cleavage/borylation of cycloketone oxime esters has been described. In this reaction, the B2(OH)4 reagent not only served as the boron source but also acted as an electron donor source through formation of a complex with a DMAc-like Lewis base.

Cited by 127 publications

References 97 publications

Deconstructive Oxygenation of Unstrained Cycloalkanamines

Deconstructive Oxygenation of Unstrained Cycloalkanamines

Iminyl-Radical-Triggered C–C Bond Cleavage of Cycloketone Oxime Derivatives: Generation of Distal Cyano-Substituted Alkyl Radicals and Their Functionalization

Recent Developments in Radical Cross‐Coupling of Redox‐Active Cycloketone Oximes

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