Thermal-mediated catalyst-free heterolytic cleavage of 3-halooxindoles: rapid access to 3-functionalized-2-oxindoles

Liu, Xiong‐Li; Yue, Jing; Chen, Shuang; Liu, Huan-Huan; Yang, Kai-Mo; Feng, Tingting

doi:10.1039/c8qo01222a

Cited by 20 publications

(8 citation statements)

References 78 publications

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“…These yields were slightly lower than those of reactions without TEMPO because these reactions might take place through an S N 1-like pathway. Liu and Zhou previously implied that the thermal-mediated heterolytic cleavage of 3-halooxindoles generated a highly electrophilic o -azaxylylenium intermediate . We thus hypothesized in situ generation of the reactive o -azaxylylenium intermediate A activated by AgSCF 3 or CuSCF 3 as a Lewis acid under mild conditions.…”

Section: Resultssupporting

confidence: 92%

Trifluoromethylthiolation of Hindered α-Bromoamides with Nucleophilic Trifluoromethylthiolating Reagents

et al. 2021

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General methods have not been previously developed for the synthesis of sterically hindered α-SCF 3 -substituted carbonyl compounds using nucleophilic trifluoromethylthiolating reagents. Thus, we herein report sp 3 C−SCF 3 bond formation in hindered α-bromoamides containing 3-bromo-oxindoles and linear α-bromoamides using CuSCF 3 or AgSCF 3 under mild conditions to access sterically hindered α-SCF 3 -substituted amides. This transformation is applicable to not only 3-SCF 3 -substituted oxindoles but also primary and secondary amides and reveals a broad functional group tolerance. This method will benefit the fields of medicinal and agricultural chemistry.

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Section: Resultssupporting

confidence: 92%

Trifluoromethylthiolation of Hindered α-Bromoamides with Nucleophilic Trifluoromethylthiolating Reagents

et al. 2021

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“…This intermediate act as the Michael acceptor, circumventing the use of an extra base and metal promoters, and giving a diversity oriented way to deal with preparation of 3‐functionalized‐2‐oxindoles bearing a tetrasubstituted core in significant yield (up to 93 % yield) (Scheme 142). [160] …”

Section: C−h Functionalization Of Pyrrolesmentioning

confidence: 99%

Recent Advances in Functionalization of Pyrroles and their Translational Potential

Hunjan

Panday

Gupta

et al. 2021

The Chemical Record

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Among the known aromatic nitrogen heterocycles, pyrrole represents a privileged aromatic heterocycle ranging its occurrence in the key component of “pigments of life” to biologically active natural products to active pharmaceuticals. Pyrrole being an electron‐rich heteroaromatic compound, its predominant functionalization is legendary to aromatic electrophilic substitution reactions. Although a few excellent reviews on the functionalization of pyrroles including the reports by Baltazzi in 1963, Casiraghi and Rassu in 1995, and Banwell in 2006 are available, they are fragmentary and over fifteen years old, and do not cover the modern aspects of catalysis. A review covering a comprehensive package of direct functionalization on pyrroles via catalytic and non‐catalytic methods including their translational potential is described. Subsequent to statutory yet concise introduction, the classical functionalization on pyrroles using Lewis acids largely following an ionic mechanism is discussed. The subsequent discussion follows the various metal‐catalyzed C−H functionalization on pyrroles, which are otherwise difficult to implement by Lewis acids. A major emphasize is given on the radical based pyrrole functionalization under metal‐free oxidative conditions, which is otherwise poorly highlighted in the literature. Towards the end, the current development of pyrrole functionalization under photocatalyzed and electrochemical conditions is appended. Only a selected examples of substrates and important mechanisms are discussed for different methods highlighting their scopes and limitations. The aromatic nucleophillic substitution on pyrroles (being an electron‐rich heterocycle) happened to be the subject of recent investigations, which has also been covered accentuating their underlying conceptual development. Despite great achievements over the past several years in these areas, many challenges and problems are yet to be solved, which are all discussed in summary and outlook.

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“…Oxindoles have drawn extensive attention as a core motif in many complex organic frameworks that exhibit a wide range of pharmacological activities . Among them, unsymmetrical 3,3-disubstituted 2-oxindoles are structural scaffolds present in a wide range of natural products and biologically active compounds .…”

Section: Introductionmentioning

confidence: 99%

Silyl Cation-Initiated, Brønsted Acid-Catalyzed Strategy toward Unsymmetrical 3,3-Disubstituted 2-Oxindoles and Azonazine Cores

et al. 2022

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Herein, a mild, metal-free, robust approach for synthesizing valuable and sterically demanding unsymmetrical 3,3-disubstituted 2-oxindoles via reductive cyclization of α-ketoamides is reported. This operationally simple protocol is initiated by a silyl cation and further catalyzed by a Brønsted acid. We have utilized a wide range of arenes, amines, and thiols as coupling partners with various α-ketoamides. The products were afforded in excellent regioselectivity and good functional group tolerance. This procedure provides easy access to the scaffolds of azonazine and its derivatives with an excellent syn-diastereoselectivity bearing all-carbon quaternary stereocenters.

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Thermal-mediated catalyst-free heterolytic cleavage of 3-halooxindoles: rapid access to 3-functionalized-2-oxindoles

Abstract: Herein a previously unreported catalyst-free SN1 reaction of the 3-halooxindoles to build 3-functionalized-2-oxindoles is described.

Cited by 20 publications

References 78 publications

Trifluoromethylthiolation of Hindered α-Bromoamides with Nucleophilic Trifluoromethylthiolating Reagents

Trifluoromethylthiolation of Hindered α-Bromoamides with Nucleophilic Trifluoromethylthiolating Reagents

Recent Advances in Functionalization of Pyrroles and their Translational Potential

Silyl Cation-Initiated, Brønsted Acid-Catalyzed Strategy toward Unsymmetrical 3,3-Disubstituted 2-Oxindoles and Azonazine Cores

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