[Discovery of cis-preference of aromatic N-methylamides and its application to molecular constructions].
Aromatic secondary amides such as benzanilide (1) exist in a trans-amide form both in the crystal and in the solution, whereas N-methylbenzanilide (2) exists in cis form in the crystal, and predominantly in a cis form in the solution. Similar cis conformational preferences were observed in aromatic N,N'-dimethylated ureas and guanidines, in which two aromatic rings are located face to face. The cis preferences of N-methylated amides, ureas and guanidines could be utilized to construct interesting aromatic architecture. N,N',N"-Trimethyl-N,N',N"-triphenyl-1,3,5-benzenetricarboxamide (20) and a cyclic triamide (24) have crystal structures in which three N-phenyl groups direct to the same orientation (syn conformation). 1,2-Bis(N-benzoyl-N-methylamino)benzene (22), which have no fixed asymmetric center, afforded chiral crystals by simple recrystallization. Furthermore, aromatic multi-layered structures could be built and applied to obtain aromatic molecules which have potent DNA-binding ability.
Azumaya
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School of Pharmaceutical Sciences, Kitasato University, 5-9-I Shirokane, Minato-ku, Tokyo 108-8641, Japan.
D000577:Amides / Q000737:chemistry*; D003460:Crystallization; D004247:DNA / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry; D008968:Molecular Conformation; D012996:Solutions; D013237:Stereoisomerism; D014508:Urea / Q000737:chemistry
D000577:Amides; D012996:Solutions; D014508:Urea; D004247:DNA; D019791:Guanidine