A chiral N-heterocyclic carbene (NHC)-catalyzed [4 + 2] annulation of γ-chloroenals and α-arylidene pyrazolinones was developed in the absence of expensive oxidants. The reaction proceeds smoothly via a vinyl enolate intermediate to afford spirocyclohexane pyrazolones in moderate to good yield (up to 86%) with high diastereoselectivities (up to 15:1 dr) and excellent enantioselectivities (up to >99%
DMAP Catalyzed Domino Rauhut–Currier Cyclization Reaction between Alkylidene Pyrazolones and Nitro-olefins: Access to Tetrahydropyrano[2,3-<i>c</i>]pyrazoles
作者:Nimisha Bania、Buddhadeb Mondal、Sounak Ghosh、Subhas Chandra Pan
DOI:10.1021/acs.joc.0c02871
日期:2021.3.5
Herein, we employ unsaturated pyrazolones in the Rauhut–Currier reaction for the first time. A domino Rauhut–Currier cyclization reaction has been developed between unsaturated pyrazolones and nitro-olefins. The trisubstituted tetrahydropyrano[2,3-c]pyrazoles were obtained in moderate to high yields with excellent diastereoselectivities. A few applications including a synthesis of disubstituted tetrahydropyrano[2
在本文中,我们首次在Rauhut-Currier反应中使用了不饱和吡唑啉酮。在不饱和吡唑啉酮和硝基烯烃之间发展了多米诺Rauhut-Currier环化反应。三取代四氢吡喃并[2,3- c ]吡唑以中等至高收率获得,具有非对映选择性。已经证明了包括合成二取代的四氢吡喃并[2,3- c ]吡唑在内的一些应用。还使用手性DMAP催化剂研究了该方法的初步催化不对称形式。
An efficient and highly diastereoselective synthesis of carbocyclic spiropyrazolones via one-pot sequential dual organo-silver catalyzed Michael-hydroalkylation reactions
作者:Khyati Shukla、Sadhna Shah、Nirmal K. Rana、Vinod K. Singh
DOI:10.1016/j.tetlet.2018.11.064
日期:2019.1
An economical approach for the diastereoselective synthesis of highly functionalized carbocyclic spiropyrazolone derivatives having one quaternary and two tertiary stereocenters along with one exocyclic double bond exploiting dual organo-silver sequential catalysis has been developed. The unified method to both cyclohexyl and cyclopentyl spirocompounds involves the reaction of γ- and β-nitroalkynes
A PPh<sub>3</sub>-catalyzed sequential annulation reaction to construct cyclopentane-fused dihydropyrazolone-pyrrolidinediones
作者:Cheng Cheng、Xiaobin Sun、Zhiwei Miao
DOI:10.1039/d0ob00815j
日期:——
An effective strategy for the synthesis of cyclopentane-fused dihydropyrazolone-pyrrolidinediones via a PPh3-catalyzed sequential annulation reaction of maleimides and unsaturated pyrazolones has been developed.
Asymmetric Synthesis of Spiropyrazolones via Chiral Pd(0)/Ligand Complex-Catalyzed Formal [4+2] Cycloaddition of Vinyl Benzoxazinanones with Alkylidene Pyrazolones
In the presence of the chiral Pd(0)/ligand complex, vinyl benzoxazinanones underwent the [4+2] cycloaddition with alkylidene pyrazolones smoothly and delivered spiropyrazolones in reasonable yields, diastereoselectivities, and eneantioselectivities (up to >99% yield, >99:1 dr and 99% ee). The absolute configuration of the obtained spiropyrazolones was unambiguously characterized with the use of X-ray