Characteristic Conformation of Mosher’s Amide Elucidated Using the Cambridge Structural Database

Molecules

Akio Ichikawa¹  Hiroshi Ono³  Yuji Mikata² 

[1] Division of Insect Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan;Department of Chemistry, Biology, and Environmental Science, Faculty of Science, Nara Women’s University, Kita-Uoya Nishi-machi, Nara 630-8506, Japan; E-Mail:;Analytical Science Division, National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan; E-Mail:

关键词: chiral recognition;    chirality;    crystal engineering;    Mosher’s method;    MTPA;   

DOI  :  10.3390/molecules200712880

来源: mdpi

【 摘 要 】

Conformations of the crystalline 3,3,3-trifluoro-2-methoxy-2-phenylpropanamide derivatives (MTPA amides) deposited in the Cambridge Structural Database (CSD) were examined statistically as R_acid-enantiomers. The majority of dihedral angles (48/58, ca. 83%) of the amide carbonyl groups and the trifluoromethyl groups ranged from –30° to 0° with an average angle θ¹ of −13°. The other conformational properties were also clarified: (1) one of the fluorine atoms was antiperiplanar (ap) to the amide carbonyl group, forming a staggered conformation; (2) the MTPA amides prepared from primary amines showed a Z form in amide moieties; (3) in the case of the MTPA amide prepared from a primary amine possessing secondary alkyl groups (i.e., Mosher-type MTPA amide), the dihedral angles between the methine groups and the carbonyl groups were syn and indicative of a moderate conformational flexibility; (4) the phenyl plane was inclined from the O–C_chiral bond of the methoxy moiety with an average dihedral angle θ² of +21°; (5) the methyl group of the methoxy moiety was ap to the ipso-carbon atom of the phenyl group.

【 授权许可】

CC BY   
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