Copper‐Catalyzed Formal [4+2] Cycloaddition of Enoldiazoimides with Sulfur Ylides

AgI -Catalyzed Reaction of Enol Diazoacetates and Imino Ethers: Synthesis of Highly Functionalized Pyrroles

An unprecedented Ag^I -catalyzed efficient method for the coupling of imino ethers and enol diazoacetates through a [3+2]-cycloaddition/C-O bond cleavage/[1,5]-proton transfer cascade process is reported. The general class of imino ethers that includes oxazolines, benzoxazoles and benzimidates are applicable substrates for these reactions that provide direct access to fully substituted pyrroles with uniformly high chemo- and regioselectivity. High variability in substitution at the pyrrole 2-, 5- and N-positions characterizes this methodology that also presents an entry point for further pyrrole diversification via facile modification of resulting N-functional pyrroles.

ZnCl2 -Catalyzed [4+1] Annulation of Alkylthio-Substituted Enaminones and Enaminothiones with Sulfur Ylides

Concise construction of furan and thiophene units has played an important role in the synthesis of potentially bioactive compounds and functional materials. Herein, an efficient Lewis acid ZnCl₂ catalyzed [4+1] annulation of alkylthio-substituted enaminones is reported, that is, α-oxo ketene N,S-acetals with sulfur ylides to afford 2-acyl-3-aminofuran derivatives. In a similar fashion, [4+1] annulation of the corresponding enaminothiones, that is, α-thioxo ketene N,S-acetals, with sulfur ylides efficiently proceeded to give multisubstituted 3-aminothiophenes. This method features wide substrate scopes as well as broad functional group tolerance, offering a concise route to highly functionalized furans and thiophenes.