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Kita’s Oxidative Spirolactonization Catalyzed by a Hypervalent Iodine(III) Species
M. Uyanik, T. Yasui, K. Ishihara*
Nagoya University and Japan Science and Technology Agency, CREST, Nagoya, Japan
22 April 2010 (online)
Ishihara and co-workers report the rational design of a conformationally flexible C 2-symmetric iodosyl arene catalyst which has been applied in the enantioselective Kita oxidative spirolactonization. Oxidant 2 is formed in situ from catalyst 1 and mCPBA. It is speculated that oxidant 2 has n-σ* or hydrogen-bonding interactions between the iodine(III) center and the amide side chain. Even a 4-benzoylnaphthol derivative could be synthesized with good enantioselectivity (er = 91:5:8.5), which only gave racemic product using Kita’s method.