Site- and Enantiodifferentiating C(sp<sup>3</sup>)–H Oxidation Enables Asymmetric Access to Structurally and Stereochemically Diverse Saturated Cyclic Ethers
作者:Shutao Sun、Yiying Yang、Ran Zhao、Dongju Zhang、Lei Liu
DOI:10.1021/jacs.0c09636
日期:2020.11.11
A manganese-catalyzed site- and enantiodifferentiating oxidation of C(sp3)-H bonds in saturated cyclic ethers has been described. The mild and practical method is applicable to a range of tetrahydrofurans, tetrahydropyrans, and medium-sized cyclic ethers with multiple stereocenters and diverse substituent patterns in high efficiency with extremely efficient site- and enantiodiscrimination. Late-stage
The firstexamples of intramolecular Pauson-Khand reactions involving ketenimines are reported. The alkyne-ketenimines participate through the C=C bond of the ketenimine fragment in the [2+2+1] cyclization process giving rise to cyclopenta[b]quinolin-2-ones. In the absence of metal carbonyl complexes, two competitive periselective cycloadditions occur when the alkyne-ketenimines are heated in benzene
“Anti-Michael addition” of Grignard reagents to sulfonylacetylenes: synthesis of alkynes
作者:Francisco Esteban、Lazhar Boughani、José L. García Ruano、Alberto Fraile、José Alemán
DOI:10.1039/c7ob00783c
日期:——
In this work, the addition of Grignardreagents to arylsulfonylacetylenes, which undergoes an “anti-Michael addition”, resulting in their alkynylation under very mild conditions is described. The simplicity of the experimental procedure and the functional group tolerance are the main features of this methodology. This is an important advantage over the use of organolithium at −78 °C that we previously
Divergent Method to <i>trans</i>-5-Hydroxy-6-alkynyl/alkenyl-2-piperidinones: Syntheses of (−)-Epiquinamide and (+)-Swainsonine
作者:Chang-Mei Si、Zhuo-Ya Mao、Han-Qing Dong、Zhen-Ting Du、Bang-Guo Wei、Guo-Qiang Lin
DOI:10.1021/acs.joc.5b00803
日期:2015.6.5
An efficient diastereoselective approach to access trans-5-hydroxy-6-alkynyl/alkenyl-2-piperidinones has been developed through nucleophilic addition of α-chiral aldimines using alkynyl/alkenyl Grignardreagents. The diastereoselectivity of alkenyl in C-6 position of 2-piperidinone was controlled by α-alkoxy substitution, while the alkynyl was controlled by the coordination of the α-alkoxy substitution
efficient cascade reaction has been developed to synthesize a series of 1,3-diols and 1,3,5-triols via reactions of arylalkynyl Grignardreagents with enol esters. The stereoselectivity of reactions and the molecular configurations of the products were confirmed by nuclear magnetic resonance, X-ray diffraction, and high-performance liquid chromatography analysis. A possible reaction mechanism was analyzed