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Communication | Special issue | Vol 58, No. 1, 2002, pp.93-97
Published online, 1st January, 1970
DOI: 10.3987/COM-02-S(M)38
Cationic Copper(II)-Oxazoline-Sulfoxide Catalysts: Application to Asymmetric Diels-Alder Reactions

Kazuhiro Watanabe, Takashi Hirasawa, and Kunio Hiroi*

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan


New chiral sulfoxides bearing a chiral 1,3-oxazoline ring were prepared and used as chiral ligands in copper(II)-catalyzed Diels-Alder reactions. The copper(II)-catalyzed cycloaddition reactions using the new chiral ligands were carried out at –78°C to afford adducts with rather high (up to 75 %) enantiomeric excess. Introduction of a counterion (triflate or hexafluoroantimonate) into the catalysts represented higher degree of asymmetric induction; namely, the more cationic copper(II)-oxazoline sulfoxide catalysts improved the enantioselectivity in the cycloaddition reaction.