Ferrocenyl chiral bisphosphorus ligands for highly enantioselective asymmetric hydrogenation via noncovalent ion pair interaction

Abstract

A new class of ferrocenyl chiral bisphosphorus ligand, Wudaphos, was developed, and exhibits excellent <i>ee</i> and activity (<i>ee</i> up to 99%, TON up to 20 000) for the asymmetric hydrogenation of both 2-aryl and 2-alkyl acrylic acids through ion pair noncovalent interaction under base free and mild reaction conditions. Well-known anti-inflammatory drugs such as naproxen and ibuprofen together with the intermediate for the preparation of Roche ester and some bioactive compounds were also efficiently obtained with excellent <i>ee</i>. Control experiments were conducted and revealed that the ion pair noncovalent interaction and chain length played important roles.