[reaction: see text] A boat-type of chelated bicyclic transition state involving highly diastereoselective construction of three contiguous stereogenic centers in the Reformatsky reaction of indium enolates with alpha-alkoxy/hydroxy ketones is proposed. alpha-Hydroxy ketones with indium enolates furnished highly diastereoselective lactones, while alpha-alkoxy ketones gave acyclic esters in moderate selectivities. X-ray structure analyses of key products unequivocally revealed the unexpected stereochemistry of products and the reaction pathway.
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http://dx.doi.org/10.1021/ol060943m | DOI Listing |
Nat Commun
May 2021
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, China.
Intermolecular addition of enols and enolates to unactivated alkynes was proved to be a simple and powerful method for carbon-carbon bond formation. Up to date, a catalytic asymmetric version of alkyne with 1,3-dicarbonyl compound has not been realized. Herein, we achieve the catalytic asymmetric intermolecular addition of 1,3-dicarbonyl compounds to unactivated 1-alkynes attributing to the synergistic activation of chiral N,N'-dioxide-indium(III) or nickel(II) Lewis acid and achiral gold(I) π-acid.
View Article and Find Full Text PDFJ Am Chem Soc
May 2017
Department of Organic Chemistry, University of Geneva, 1211 Geneva, Switzerland.
This report focuses on the remote control of anion-π catalysis by electric fields. We have synthesized and immobilized anion-π catalysts to explore the addition reaction of malonic acid half thioesters to enolate acceptors on conductive indium tin oxide surfaces. Exposed to increasing electric fields, anion-π catalysts show an increase in activity and an inversion of selectivity.
View Article and Find Full Text PDFJ Org Chem
August 2015
Department Chemie-Biologie, Universität Siegen, Adolf-Reichwein-Strasse 2, D-57068 Siegen, Germany.
The domino-aldol-aldol-hemiacetal-reaction cascade of indium and other group 13 metal enolates furnished 6-deoxy-α-D,L-altropyranose derivatives in up to 99% yield under thermodynamic control. At lower temperature and thus under kinetic control, the reaction proceeded in a much less diastereoselective manner. The changeover from kinetic to thermodynamic control operating in this multistep domino-aldol-aldol-hemiacetal protocol was used for probing the efficiency of DFT computations.
View Article and Find Full Text PDFUltrason Sonochem
November 2015
Dipartimento di Scienza e Alta Tecnologia, University of Insubria, Via Valleggio 11, 22100 Como, Italy.
An ultrasound-assisted three-component, one-pot domino reaction with ferrocenecarboxaldehyde is herein reported. The sequence of reactions entails the allylindation and dehydrative alkylation of stabilized C-nucleophiles (e.g.
View Article and Find Full Text PDFChem Commun (Camb)
March 2015
Department of Chemistry, Pukyong National University, Busan, 608-737, Republic of Korea.
We report an indium triflate-catalyzed stereoselective intramolecular tandem conjugate addition of secondary amines to α,β-bisenones to afford a 1,2,3-trisubstituted six-membered ring bearing diketone substituents in good to excellent yields at room temperature. Various kinds of α,β-bisenones and amines were employed to expand the scope of this chemistry. Intramolecular trapping of indium-enolate by the tethered electrophiles resulted in the stereoselective formation of three contiguous stereogenic centers.
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