Highly enantioselective catalytic asymmetric [2+2] cycloadditions of cyclic α-alkylidene β-oxo imides with ynamides
Kazuaki Enomoto1, Harufumi Oyama, Masahisa Nakada
1Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan), Fax: (+81) 3-5286-3240, Home page: http://www.chem.waseda.ac.jp/nakada/
Abstract:
Highly enantioselective catalytic asymmetric [2+2] cycloadditions of cyclic α-alkylidene β-oxo imides with ynamides are described. The high reactivity of the cyclic α-alkylidene β-oxo imide allows the [2+2] cycloadditions of a hindered substrate with unreactive ynamides at low temperature. The X-ray crystallographic analysis of the product suggests that the enantioselectivity of the [2+2] cycloaddition can be well explained by the chelate model comprising the intramolecular hydrogen bond, wherein the cyclic α-alkylidene β-oxo imide coordinates with Cu(II) through the two imide carbonyls. The imide group in the product can be transformed to amide, nitrile, and ester groups; moreover, it is removable.
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