Munoz-Herranz, Maria and Adrio, Javier and Carretero, Juan Carlos and Echavarren, Antonio M. (2005) Ligand Effects in Gold- and Platinum-Catalyzed Cyclization of Enynes: Chiral Gold Complexes for Enantioselective Alkoxycyclization. Organometallics, 24 (6). pp. 1293-1300. ISSN 0276-7333
Full text not available from this repository.Abstract
Phosphine and bidentate N-N ligands inhibit the Alder-ene-type cycloisomerization of enynes catalyzed by Pt(II) and favor the alkoxycyclization process. The enantioselective Pt(II)-catalyzed alkoxycyclization has been studied in the presence of chiral mono- and bidentate phosphines, as well as chiral bidentate N-N ligands. Modest levels of enantioselection (up to 50% ee) have been obtained with Tol-BINAP as ligand. The alkoxycyclizations with a catalyst formed from [Au(L)Cl]/AgX proceed more readily, and up to 94% ee's have been obtained using [(AuCl)2(Tol-BINAP)] (47) as the precatalyst. The X-ray crystal structures of Au(I) complexes 47 and chloro-(R)-2-(tert-butylsulfenyl)-1-(diphenylphosphino)ferrocene gold(I) (39) show the AuCl fragments monocoordinated with the P centers of the chiral phosphine ligands.