ChemInform Abstract: Studies on the Transition Metal‐Catalyzed Synthesis of Variously Substituted (E)‐3‐[1‐(Aryl)methylidene]‐ and (E)‐3‐(1‐Alkylidene)‐3H‐furan‐2‐ones.

Abstract

Studies on the Transition Metal-Catalyzed Synthesis of Variously Substituted (E)-3-[1-(Aryl)methylidene]-and (E)-3-(1-Alkylidene)-3H-furan-2-ones.-Title compounds like (II), (V), and (VII) can be prepared by Ag-or Pd-catalyzed cyclization of propenoic acids of type (I) or by a tandem cross-coupling-lactonization process. The former leads to better results. Unfortunately, during the tandem process isomerization to furanones of type (VIII) can occur. Quantitative and stereoselective isomerization is observed on Pd-catalyzed cyclization of the acid (Id) in the presence of phenyl iodide. The desired furanone (XI) cannot be isolated. -(ROSSI, R.; BELLINA, F.; BECHINI, C.; MANNINA, L.; VERGAMINI, P.; Tetrahedron 54 (1998) 1-2, 135-156; Dip. Chim. Chim. Ind., Univ. Pisa, CNR, I-56126 Pisa, Italy; EN)