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Solvent‐Dependent Self‐Discrimination of Bis(2‐hydroxyphenyl)diamides
Author(s) -
Matsuzawa Akinobu,
Nojiri Akihiro,
Kumagai Naoya,
Shibasaki Masakatsu
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000321
Subject(s) - chemistry , dichloromethane , solubility , solvent , ethyl acetate , hydrogen bond , chloroform , enantiomer , alcohol , hildebrand solubility parameter , acetonitrile , selectivity , single crystal , molecule , organic chemistry , catalysis , medicinal chemistry , crystallography
Abstract Solvent‐dependent, self‐discrimination of diamides is described. Mixing a solution of ( R )‐ 1 a and ( S )‐ 1 a , 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 1 a . The solubility of heterochiral 1 a 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 1 a in halogenated solvent was exploited to achieve high stereoselectivity in a catalytic asymmetric reaction by using a low enantiomeric excess sample of 1 a .