In recent years, gold-catalyzed intermolecular alkyne oxidation by an N-oxide oxidant, which presumably involves a gold carbenoid intermediate, has attracted increasing attention because it circumvents the employment of hazardous and potentially explosive diazocarbonyl compounds as starting materials for carbene generation. More importantly, the development of a catalytic enantioselective version of the reaction can help achieve an array of asymmetric synthesis processes modified from various racemic transformations of the gold carbenoid intermediate. In this review, we will present an overview of these recent advances in the asymmetric transformations by utilizing chiral ligands, chiral N,N'-dioxides and chiral substrates, aiming to facilitate progress in this fascinating field of research.
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http://dx.doi.org/10.1039/c9ob01096c | DOI Listing |
J Am Chem Soc
July 2023
College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, No. 2318, Yuhangtang Road, Hangzhou 311121, Zhejiang China.
Metallacarboranes have attracted significant attention due to their unique properties. Considerable efforts have been made on the reactions around the metal centers or the metal ion itself, while transformations of functional groups of the metallacarboranes have been much less explored. We presented here the formation of imidazolium-functionalized nickelacarboranes (), their subsequent conversion to nickelacarborane-supported -heterocyclic carbenoids (NHCs, ), and the reactivities of toward Au(PPh)Cl and Se powder, which resulted in the formation of bis-gold carbene complexes () and NHC selenium adducts ().
View Article and Find Full Text PDFChem Commun (Camb)
February 2022
School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho Midori-ku, Yokohama, 226-8503, Japan.
Isoxazoloazaborines 3 and 5 have been synthesized from 4--propargylaminoisoxazole 1 gold(I)-catalyzed propargyl aza-Claisen rearrangement followed by electrophilic borylative cyclization in 27-86% yields. generation of isoxazole 2 having an amino group and allenyl functionality is essential to give highly substituted isoxazoloazaborines 3 and 5, although the conventional propargyl aza-Claisen rearrangement readily affords the corresponding nitrogen-containing heterocycles, such as pyridines and pyrroles. The resulting isoxazoloazaborine 5a underwent the N-O bond insertion of zinc carbenoid to give oxazine-fused azaborine 6 in 48% yield.
View Article and Find Full Text PDFChem Commun (Camb)
November 2021
Department of Chemistry, Renmin University of China, 59# Zhongguancun Street, Haidian, Beijing 100872, China.
A gold catalyzed formal intermolecular [2+3] cyclo-coupling of 1,3-enynes with phenols was developed to prepare dihydrobenzofuran derivatives with the addition of 2,6-dichloropyridine -oxide, in which, a highly -selective phenol SAr functionalization was achieved by using 1,3-enynes as α-oxo vinyl gold carbenoid surrogates.
View Article and Find Full Text PDFChem Rec
December 2021
School of Chemistry, University of Birmingham Edgbaston, Birmingham, B15 2TT, UK.
The combination of a nucleophilic nitrene equivalent, a triple bond and a π-acid catalyst has underpinned numerous efficient transformations for the preparation of azacycles. This personal account details our efforts in developing an annulation strategy. Adding a nucleophilic nitrenoid to an activated alkyne can generate carbenoid character that is then quenched by a cyclisation onto the nitrenoid substituent.
View Article and Find Full Text PDFOrg Lett
August 2020
Laboratory for Organic & Microwave-Assisted Chemistry (LOMAC), Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001, Leuven, Belgium.
A gold(I)-catalyzed cascade transformation of -alkynic 2-ynamides for the rapid and efficient synthesis of the indolizidine scaffold is developed. Through a sequential nucleophilic cyclization/enyne cycloisomerization/1,2-migration process, diverse pyrrolo[1,2-]isoquinolines are obtained under mild conditions in a regiospecific and convergent manner. Various alkyl and aryl migrating groups are tolerated in this process.
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