title: Absolute helical arrangement of sulfonamide in the crystal.
abstract: [reaction: see text] 1,2-Bis(N-benzenesulfonyl-N-methylamino)benzene (2), which has no fixed asymmetric element, was crystallized from ethyl acetate as chiral crystals belonging to space group P4(1)2(1)2 (No. 92) or P4(3)2(1)2 (No. 96). The array of molecules built by the CH-pi interaction along the c-axis forms an enantiomeric helical superstructure in each individual crystal. The absolute configurations of the chiral crystals of 2 were determined by X-ray crystal structure analysis using the Flack parameter method. The solid-state CD spectra of the chiral crystals in KBr were mirror images. The equilibrium between the two enantiomers in solution is fast during crystallization at ambient temperature, and the energy barrier (DeltaG()) is estimated to be 11.7 +/- 0.3 kcal/mol (233 K).
authors.affiliation: School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Minato-ku, Shirokane, Tokyo 108-8641, Japan. azumayai@pharm.kitasato-u.ac.jp
authors.forename: Isao
authors.initials: I
authors.lastname: Azumaya
authors.forename: Takako
authors.initials: T
authors.lastname: Kato
authors.forename: Iwao
authors.initials: I
authors.lastname: Okamoto
authors.forename: Ryu
authors.initials: R
authors.lastname: Yamasaki
authors.forename: Aya
authors.initials: A
authors.lastname: Tanatani
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kagechika
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takayanagi