First enantioselective one-pot, three-component imino Reformatsky reaction*
Pier Giorgio Cozzi and Eleonora Rivalta
Alma Mater Studiorum, University of Bologna, Dipartimento di Chimica "G. Ciamician", Via Selmi 2, 40126 Bologna, Italy
Abstract: The Reformatsky reaction is the well-recognized carbon-carbon bond-forming reaction of α-halo esters with aldehydes or ketones in the presence of Zn metal to give β-hydroxy esters. Recently, it has been reported that Rh- and Ni-catalyzed Reformatsky reaction, in which R2Zn (R = Me, Et) acts as the Zn source, reacted smoothly with carbonyl compounds and imines. Taking advantage of N-methylephedrine as a cheap and recoverable chiral ligand, we have discovered the first homogeneous enantioselective Ni-catalyzed imino Reformatsky reaction. The process is a one-pot, three-component reaction, in which Me2Zn plays multiple roles as dehydrating agent, reductant, and coordinating metal. Broad scope, high enantiomeric excess, and a simple procedure are adding value to our findings.
Keywords: Reformatsky; Me2Zn; nickel; N-methylephedrine; amino esters.
*Pure Appl. Chem. 78, 197-523. An issue of reviews and research papers based on lectures presented at the 13th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS-13), Geneva, Switzerland, 17-21 July 2005.