all-carbon 1,4-dipoles could be generated selectively from the gold(I)-catalyzed cycloisomerizations of allenyl ketones bearing a cyclopropyl moiety, which undergo [4 + 3] cycloadditions with nitrones to produce two regiomers of furan-condensed N,O-seven-membered rings in moderate to excellent yields highly selectively.
<sup>13</sup>C and<sup>1</sup>H NMR of Arylnitrones. Substituent Effects of α-Phenyl-<i>N</i>-(<i>p</i>-substituted phenyl)nitrones
作者:Kohji Suda、Toshio Tsujimoto、Masashige Yamauchi
DOI:10.1246/bcsj.60.3607
日期:1987.10
Substituent effects on the chemical shifts of the conjugation sites in α-phenyl-N-arylnitrones (2) have been investigated. Resonance effects predominate at these positions. The electronic effects of the substituents should be treated separately between electron-donating groups and electron-withdrawing ones. A plausible mechanism for the transmission of the substituent effects in 2 has been proposed.
Sc(OTf)3-Catalyzed [3+2]-Cycloaddition of Diazoacetoacetate Enones and N-Aryl Nitrones: Diastereoselective Synthesis of Functionalized Isoxazolidines with Three Contiguous Stereogenic Centers
作者:Xichen Xu、Yingjun Zhao、Di Wu
DOI:10.1055/s-0041-1737804
日期:2022.5
A catalytic [3+2]-cycloaddition using Sc(OTf)3 as a Lewis acid catalyst is developed. This catalytic 1,3-dipolar cycloaddition diastereoselectively transforms diazoacetoacetate enones and N-aryl nitrones into highly functionalized isoxazolidines bearing three contiguous chiral centers. The feasibility of the uncatalyzed 1,3-dipolar cycloaddition is postulated by DFT calculations and substantiated
Stereoselective Kinugasa/Aldol Cyclization: Synthesis of Enantioenriched Spirocyclic β-Lactams
作者:Alexa Torelli、Eun Seo Choi、Aurélien Dupeux、Marcel Nicolas Perner、Mark Lautens
DOI:10.1021/acs.orglett.3c03534
日期:2023.12.1
We report an enantioselective copper-catalyzed Kinugasa/aldol domino reaction. This strategy enables access to a range of spirocyclic β-lactam pyrrolidinones in a stereoselective fashion. Under mild reaction conditions, prochiral alkyne-tethered ketones are coupled with nitrones to enable the facile construction of two spirofused ring systems containing three continuous stereocenters with excellent
Asymmetric Pericyclic Cascade Approach to Spirocyclic Oxindoles
作者:Edward Richmond、Nicolas Duguet、Alexandra M. Z. Slawin、Tomáš Lébl、Andrew D. Smith
DOI:10.1021/ol300982f
日期:2012.6.1
The reaction of chiral N-arylnitrones with carbocyclic alkylarylketenes generates spirocyclic oxindoles in good yields and with excellent levels of enantioselectivity (90-99% ee) via a pericyclic cascade process.