A novel method for metal‐free oxothiolation of ynamides to construct oxazolidine‐2,4‐diones bearing sulfur‐substituted quaternary carbonatoms has been developed. It represents a rare C−O bond cleavage of ynamides, as well as a facile and tandem approach for the formation of C−O, C−S, and C−Cl bonds. This redox‐neutral protocol can be applied to the synthesis of multisubstituted oxazolidine‐2,4‐diones
Alkylative carboxylation of ynamides with CO2 and dialkylzinc reagents using a N‐heterocyclic carbene (NHC)–copper catalyst has been developed. A variety of ynamides, both cyclic and acyclic, undergo this transformation under mild conditions to afford the corresponding α,β‐unsaturated carboxylic acids, which contain the α,β‐dehydroamino acid skeleton. The present alkylative carboxylation formally consists
A Unified Approach for Divergent Synthesis of Heterocycles
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TMSOTf‐Catalyzed Formal [3+2] Cycloaddition of Electron‐Rich Alkynes
作者:Ping Chen、Wei Cao、Xiangqian Li、Dayong Shi
DOI:10.1002/adsc.202100769
日期:2021.10.19
construction of polysubstituted five-membered heterocycles via TMSOTf-catalyzed formal [3+2] cycloaddition of electron-rich alkynes, which features free from any metal, atom economy and water as the main by-product. Furthermore, alkenyl ether adduct has been verified as the key intermediate. Notably, by utilizing this approach, we can synthesize a broad range of polysubstituted furans, thiophenes and pyrroles
Transition-Metal-Free Tunable Chemoselective N Functionalization of Indoles with Ynamides
作者:Alexandre Hentz、Pascal Retailleau、Vincent Gandon、Kevin Cariou、Robert H. Dodd
DOI:10.1002/anie.201402767
日期:2014.8.4
Two unprecedented Nfunctionalizations of indoles with ynamides are described. By varying the electron‐withdrawing group on the ynamide nitrogen atom, either Z‐indolo‐etheneamides or indolo‐amidines can be selectively obtained under the same metal‐free reaction conditions. The scope and synthetic potential of these reactions, as well as some mechanistic insights provided by DFT calculations, are reported
A mild and efficient methodology involving Pd(PPh3)4-catalyzed intramolecular cyclization of N-alkynyl alkyloxycarbamates with CuCl2 or CuBr2 for the synthesis of 4-halo-oxazolones was developed. This reaction exhibiting good functional tolerance provided a new, efficient, and rapid synthetic process to 4-halo-oxazolones. The resulting 4-halo-oxazolones can serve as great potential precursors for the