Tertiary Amines as Synthetic Equivalents of Vinyl Cations: Zinc Bromide Promoted Coupling of Propargylamines with α-Isocyanoacetamides To Give 2,4,5-Trisubstituted Oxazoles Initiated by an Internal Redox Process
作者:Yann Odabachian、Qian Wang、Jieping Zhu
DOI:10.1002/chem.201302106
日期:2013.9.9
Crabée interrupted: Propargylamines 1 react with α-isocyanoacetamides 2 in the presence of zinc bromide to afford vinyl oxazoles 3. The transformation, wherein the propargylamine acts as a vinyl cation syntheticequivalent, involves a domino sequence incorporating a 1,5-hydride shift, intermolecular trapping/cyclization, and a 1,6-elimination (see scheme).
Selective Formation of 2-Imidazolines and 2-Substituted Oxazoles by Using a Three-Component Reaction
作者:Niels Elders、Eelco Ruijter、Frans J. J. de Kanter、Marinus B. Groen、Romano V. A. Orru
DOI:10.1002/chem.200800271
日期:2008.5.29
Selective formation of 2H-2-imidazolines and 2-substituted oxazoles by using a multicomponent reaction of amines, either aldehydes or ketones, and alpha-acidic isocyano amides or esters is described. By selecting the appropriate solvent, Ag(I) or Cu(I) catalyst, or by employing a weak Bronsted acid, the product formation can be fully controlled and directed quantitatively to the desired heterocyclic