Development of Chiral Spiro Ligands for Metal-Catalyzed Asymmetric Reactions

• Published in: Bulletin of the Chemical Society of Japan Vol. 82; no. 3; pp. 285 - 302
• Main Authors: Bajracharya, Gan B, Arai, Midori A, Koranne, Priti S, Suzuki, Takeyuki, Takizawa, Shinobu, Sasai, Hiroaki
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 15-03-2009; Chemical Society of Japan
• Series: The Chemical Society of Japan Award for Creative Work for 2005
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.82.285

This account focuses our works on the development of chiral spiro ligands bearing N-heterocycles as metal-coordinating units and their applications in the metal-catalyzed asymmetric reactions. The spiro bis(isoxazoline) ligands (SPRIXs), spiro bis(isoxazole) ligands, and spiro (isoxazole–isoxazoline) ligands were readily synthesized through intramolecular double nitrile oxide cycloaddition of the corresponding dioximes as a key step. An unprecedented activation of olefins was displayed by the PdII complexes of these chiral spiro ligands in the enantioselective oxidative cyclizations, for example; the asymmetric tandem cyclization of dialkenyl alcohol via oxy-palladation produced a bicyclic ether in excellent enantioselectivity and enantioselective version of the aminocarbonylation proceeded for the first time. Other hitherto known chiral ligands we examined failed to promote these reactions.