Lanthanide iodides, a new family of efficient Lewis acid catalysts

Samarium diiodide and other lanthanide iodides are very efficient Lewis aci d catalysts for numerous reactions such as Mukaiyama aldol and Michael reac tions, preparation of enoxysilanes, cycloaddition reactions and ring openin g of oxiranes by silylated nucleophiles or amines. Activities and selectivi ties of catalysts vary with the nature of the metal and the ligands for som e reactions. Lanthanide iodides coordinated by a cyclopentadienyl ligand wi th an asymmetric center and an ether function on a pendant chain have been characterized and tested for catalysis: low enantioselectivities are observ ed for complexes with intramolecular coordination. (C) 1998 Elsevier Scienc e S.A. All rights reserved.