- Catalytic System-Controlled Divergent Reaction Strategies for the Construction of Diversified Spiropyrazolone Skeletons from Pyrazolidinones and Diazopyrazolones
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A catalytic system-controlled divergent reaction strategy was here reported to construct four types of intriguing spiroheterocyclic skeletons from simple and readily available starting materials via a precise chemical bond activation/[n+1] annulation cascade. The tetraazaspiroheterocyclic and trizazspiroheterocyclic scaffolds could be independently constructed by a selective N?N bond activation/[n+1] annulation cascade, a C(sp2)-H activation/[4+1] annulation and a novel tandem C(sp2)-H/C(sp3)?H bond activation/[4+1] annulation strategy, along with a broad scope of substrates, moderate to excellent yields and valuable transformations. More importantly, in these transformations, we are the first time to capture a N?N bond activation and a C(sp3)?H bond activation of pyrazolidinones under different catalytic system.
- Fang, Feifei,Han, Xu,Hu, Shulei,Li, Chunpu,Liu, Hong,Wang, Qian,Wang, Run,Zhou, Yu
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supporting information
p. 21327 - 21333
(2021/08/20)
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- Spirocyclopropanes from Intramolecular Cyclopropanation of Pyranopyrazoles and Pyranopyrimidine-diones and Lewis Acid Mediated (3 + 2) Cycloadditions of Spirocyclopropylpyrazolones
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A robust intramolecular cyclopropanation reaction was first performed on pyranopyrazole and pyranopyrimidine-dione derivatives to obtain spirocyclopropylpyrazolones and barbiturates, using iodosylbenzene (PhIO) or the combination of iodobenzene diacetate (PIDA)/molecular iodine (I2), under mild reaction conditions. Syntheses of functionally and stereochemically diversified, novel spiropyrazolone fused 2-iminothiophene and spiropyrazolone fused pyrroline scaffolds were also demonstrated via Lewis acid catalyzed highly diastereoselective (3 + 2) cycloaddition reactions of the synthesized spiro-cyclopropyl pyrazolones with phenyl isothiocyanate and benzonitrile, respectively.
- Mukherjee, Prasun,Das, Asish R.
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p. 2794 - 2802
(2017/03/14)
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