title: Solvent-dependent self-discrimination of bis(2-hydroxyphenyl)diamides.
abstract: Solvent-dependent, self-discrimination of diamides is described. Mixing a solution of (R)-1a and (S)-1a, which are valine-derived, bis(2-hydroxyphenyl)diamide-bearing, multiple hydrogen-bonding modules, in dichloromethane immediately led to the formation of a thick suspension comprising a 1:1 heterochiral aggregate of 1a. The solubility of heterochiral 1a was substantially lower in halogenated solvents than in ethyl acetate. A perusal of racemic crystal structures obtained from chloroform and ethyl acetate revealed a significant difference in the crystal-packing pattern, which is likely to be the basis for the pronounced difference in solubility. Specific self-discrimination of 1 a in an ensemble of eight structurally related molecules showcased the specific aggregation through the hydrogen-bonding network of the bis(2-hydroxyphenyl)diamide framework. The low solubility of heterochiral 1a in halogenated solvent was exploited to achieve high stereoselectivity in a catalytic asymmetric reaction by using a low enantiomeric excess sample of 1a.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Akinobu
authors.initials: A
authors.lastname: Matsuzawa
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nojiri
authors.forename: Naoya
authors.initials: N
authors.lastname: Kumagai
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Shibasaki
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D002384:Catalysis; D003958:Diamide / Q000737:chemistry*; D006846:Hydrocarbons, Halogenated / Q000737:chemistry; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D006846:Hydrocarbons, Halogenated; D008024:Ligands; D010455:Peptides; D010636:Phenols; D012997:Solvents; D003958:Diamide