940602-85-7Relevant academic research and scientific papers
Unprecedented Multicomponent Organocatalytic Synthesis of Propargylic Esters via CO2 Activation
Papastavrou, Argyro T.,Pauze, Martin,Gómez-Bengoa, Enrique,Vougioukalakis, Georgios C.
, p. 5379 - 5386 (2019/03/21)
An efficient and straightforward organocatalytic method for the direct, multicomponent carboxylation of terminal alkynes with CO2 and organochlorides, towards propargylic esters, is reported for the first time. 1,3-Di-tert-butyl-1H-imidazol-3-ium chloride, a simple, widely-available, stable, and cost-efficient N-heterocyclic carbene (NHC) precursor salt was used as the (pre)catalyst. A wide range of phenylacetylenes, bearing electron-withdrawing or electron-donating substituents, react with allyl-chlorides, benzyl chlorides, or 2-chloroacetates, providing the corresponding propargylic esters in low to excellent yields. DFT calculations on the mechanism of this transformation indicate that the reaction is initiated with the formation of an NHC-carboxylate, by addition of the carbene to a molecule of CO2. Then, the nucleophilic addition of this species to the corresponding chlorides has been computed to be the rate limiting step of the process.
