Diastereoselective Synthesis of Thieno[3′,2′:4,5]cyclopenta[1,2‐d][1,3]oxazolines − New Ligands for the Copper‐Catalyzed Asymmetric Conjugate Addition of Diethylzinc to Enones

Abstract

AbstractSeveral new ligands featuring a rigid three ring skeleton have been prepared for the first time following a modular approach. Chirality has been introduced by use of an oxazoline moiety fused with a cyclopenta[b]thiophene backbone. The efficiency and stereochemical impact of these ligands on the copper‐catalyzed enantioselective addition of Et2Zn to chalcone was examined and enantiomeric excesses up to 79% were achieved using the ligand (R,R)‐16 substituted with a methyl group at the cyclopenta moiety. Computational and ESI‐mass spectral studies show that these new compounds behave as monodentate ligands towards Cu+. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)