Crystal structure of 1,2-bis(N-methyl-2-fluorobenzoylamino)benzene.

both as crystals and in solution.1–3 There are rare examples of trans amide of N-methyl aromatic anilide in crystals, though the introduction of methyl group(s) ortho to the amide bond reduces the ratio of the cis-amide form of N-methylbenzanilides in solution.3 In this paper, we report on the crystal structure of 1,2-bis(N-2-fluorobenzoyl-N-methylamino)benzene (1, Fig. 1), which has two trans-amide structures, even though the amides are tertiary. Compound 1 was synthesized by the 2-fluorobenzoylation of o-phenylenediamine in pyridine, followed by N-methylation (NaH, methyl iodide in THF:DMF = 1:5). Prismatic single crystals of 1 were obtained by recrystallization from ethyl acetate. Intensity data were collected on a Rigaku AFC5R diffractmeter using Cu Kα radiation monochromated with graphite at 296 K. The crystal data are summarized in Table 1. 1403 ANALYTICAL SCIENCES DECEMBER 2002, VOL. 18 2002 © The Japan Society for Analytical Chemistry