Synthesis and Desymmetrization of meso -2,3-Diphenylpiperazine for Application in Asymmetric Transformations

Zinc Iodide Catalyzed Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones

A straightforward, user-friendly, efficient protocol for the one pot, ZnI₂-catalyzed allenylation of terminal alkynes with pyrrolidine and ketones, toward trisubstituted allenes, is described. Trisubstituted allenes can be obtained under either conventional heating or microwave irradiation conditions, which significantly reduces the reaction time. A sustainable, widely available, and low-cost metal salt catalyst is employed, and the reactions are carried out under solvent-free conditions. Among others, synthetically valuable allenes bearing functionalities such as amide, hydroxyl, or phthalimide can be efficiently prepared. Mechanistic experiments, including kinetic isotope effect measurements and density functional theory (DFT) calculations, suggest a rate-determining [1,5]-hydride transfer during the transformation of the intermediate propargylamine to the final allene.

Computational and experimental studies on Cu/Au-catalyzed stereoselective synthesis of 1,3-disubstituted allenes

Thorough mechanistic investigation unveils details of the allenylation of terminal alkynes (ATA) under Crabbé-like conditions allowing for an enantioselective approach.