- Catalytic System-Controlled Divergent Reaction Strategies for the Construction of Diversified Spiropyrazolone Skeletons from Pyrazolidinones and Diazopyrazolones
-
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
-
p. 21327 - 21333
(2021/08/20)
-
- Construction of Multifunctionalized Azopyrazoles by Silver- Catalyzed Cascade Reaction of Diazo Compounds
-
A variety of multisubstituted azopyrazoles were synthesized in good yield from an efficient one-pot silver trifluoromethanesulfonate (AgOTf)-catalyzed cascade reaction of α-diazo-β-keto esters with two arylhydrazines or two arylhydrazine hydrochlorides. This cascade reaction included pyrazolone formation, NH insertion, and oxidation. For the synthesis of more diverse azopyrazoles bearing two different aromatic rings, the silver(I)-catalyzed cascade reaction of 4-diazopyrazol-3-one with arylhydrazine hydrochlorides was also developed. The advantages of these methodologies are easy handling, mild reaction conditions, and an effective and non-toxic catalyst usage.
- Pandit, Rameshwar Prasad,Lee, Yong Rok
-
supporting information
p. 2657 - 2664
(2015/09/01)
-
- Reactive intermediates in the photochemistry of 4-diazo-2-pyrazolin-5-ones
-
Photolysis of 4-diazo-2-pyrazolin-5-ones in methanol gives a mixture of stereoisomeric methyl 3-aryl-(or alkyl-)azo-2-alkenoates.A study of the absorption spectra of the species generated upon steady-state photolyses in glasses at 77 K, in solution at 296
- Umrigar, Pesi,Griffin, Gary W.,Ege, Seyhan N.,Adams, Alan D.,Das, Paritosh K.
-
p. 2456 - 2463
(2007/10/02)
-
- 1,3-Dipolar Cycloaddition Reactions of Diazopyrazolinones with Electron-Deficient Dipolarophiles
-
A study of the reactivity of a series of 4-diazopyrazolin-5-ones toward dipolar cycloaddition with electron-deficient olefinic and acetylenic dipolarophiles has been carried out.Reactions with dimethyl acetylenedicarboxylate afford pyrazolotriazin-7-ones which result from dipolar cycloaddition followed by a van Alphen-Huttel rearrangement of the initially produced spiro 3H-pyrazole adducts.Reaction with unsymmetrical acetylenic esters afforded variable mixtures of regioisomeric pyrazolotriazinones and 1H-furopyrazoles.Product formation has been rationalized in terms of a sustituent-dependent partitioning between spiro 3H-pyrazole adducts and ring-opened diazoalkanes.Spirocarboxylate esters were the only products isolated from reactions with acrylate ester.
- Padwa, Albert,Woolhouse, Anthony D.,Blount, John J.
-
p. 1069 - 1074
(2007/10/02)
-