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Asymmetric Synthesis of Axially Chiral Benzamides and Anilides by Enantiotopic Lithiation of Prochiral Arene Chromium Complexes

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journal contribution
posted on 13.02.2002, 00:00 by Hiroshige Koide, Takeshi Hata, Motokazu Uemura
Axially chiral benzamides and anilides were prepared by enantiotopic lithiation at the distinguished benzylic methyl of prochiral tricarbonylchromium complexes of N,N-diethyl 2,6-dimethylbenzamide (1) and N-methyl-N-acyl 2,6-dimethylaniline (14 and 21) with a chiral lithium amide base followed by electrophilic substitution in good yields with high optical purity. The resulting axially chiral chromium-complexed benzamides and anilides were oxidized under air to give chromium-free axially chiral benzamides and anilides in an enantiomerically active form without axial bond rotation at room temperature.