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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 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.