Axially chiral N,N-diethyl 2,6-disubstituted benzamides are prepared stereoselectively in an optically active form from a planar chiral (arene)chromium complex.
Ortho versus adjacent-benzylic directed lithiations of substituted N,N-diethylbenzamides
作者:John J. Court、Dennis J. Hlasta
DOI:10.1016/0040-4039(96)00016-0
日期:1996.2
Directed lithiation of substituted 2-n-alkyl N,N-diethylbenzamides gave mixtures of ortho and adjacent-benzylic alkylated products (2 and 3). The ratios of isolated products were dependent upon the substitution patterns of the benzene ring and on the reaction conditions. Substrates and reaction conditions that favor either ortho or adjacent-benzylic lithiation are presented.
Asymmetric Synthesis of Axially Chiral Benzamides and Anilides by Enantiotopic Lithiation of Prochiral Arene Chromium Complexes
作者:Hiroshige Koide、Takeshi Hata、Motokazu Uemura
DOI:10.1021/jo011052p
日期:2002.3.1
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
6-dimethylbenzamide and N-methyl-N-acyl-2,6-dimethylaniline with a chiral lithium amide followed by electrophilic substitution. The resulting axially chiral chromium-complexed benzamides and anilides were oxidized in air to give chromium-free axially chiral benzamides and anilides in enantiomericallyenriched form without axial bond rotation at room temperature.