Front Cover: Synthesis of Tetrahydro‐4H‐pyrido[1,2‐b]isoquinolin‐4‐ones from Ugi 4‐CR‐Derived Dihydroisoquinoline‐Xanthates (Eur. J. Org. Chem. 22/2022)

Abstract

The Front Cover illustrates an efficient protocol for synthesizing polyfunctionalized tetrahydro‐4H‐pyrido[1,2‐b]isoquinolinones. The methodology highlights the power of combining the four‐component Ugi reaction with a xanthate‐based radical cascade process to achieve molecular complexity in a few steps. The cover art features the beautiful library building of the authors’ University in Mexico City and the waterfall in the Basaltic Prisms, Huasca de Ocampo, Hidalgo, Mexico. More information can be found in the Research Article by L. D. Miranda et al.

Propargyl Amines: Versatile Building Blocks in Post‐Ugi Transformations

“…Here, in the Ugi reaction, chloroacetic acid, propargyl amine, isocyanide and different aldehydes reacted at room temperature for 48 h and gave 70–89 % of yield. [16] These Ugi products, upon alkyne activation using the cationic gold catalyst JohnPhosAu(MeCN)SbF 6 (5 mol %) at room temperature in chloroform, underwent annulation via intramolecular nucleophilic exo attack and produced exo ‐dihydroisoquinolines. However, these exo ‐dihydroisoquinolines were not isolated, but converted into the endo isomers using Pd(OAc) 2 (5 mol %), B 2 Pin 2 (10 mol %) and PCy 3 HBF 4 (10 mol %) at 80 °C in toluene and were then reacted with KSCSOEt (1.2 equiv.)…”

“…Miranda and co‐workers synthesized dihydroisoquinoline‐xanthates through a cyclization using a gold catalyst for post‐Ugi alkyne activation (Scheme 4). Here, in the Ugi reaction, chloroacetic acid, propargyl amine, isocyanide and different aldehydes reacted at room temperature for 48 h and gave 70–89 % of yield [16] . These Ugi products, upon alkyne activation using the cationic gold catalyst JohnPhosAu(MeCN)SbF 6 (5 mol %) at room temperature in chloroform, underwent annulation via intramolecular nucleophilic exo attack and produced exo ‐dihydroisoquinolines.…”