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- Title
Weak C-H...O and C-H...π hydrogen bonds and π-π stacking interactions in a series of four N′-[( E)-(aryl)methylidene]- N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazides.
- Authors
Nogueira, Thais C. M.; Pinheiro, Alessandra C.; Wardell, James L.; Souza, Marcus V. N. de; Abberley, Jordan P.; Harrison, William T A
- Abstract
Oxazolidin-2-ones are widely used as protective groups for 1,2-amino alcohols and chiral derivatives are employed as chiral auxiliaries. The crystal structures of four differently substituted oxazolidinecarbohydrazides, namely N′-[( E)-benzylidene]- N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12N3O3, (I), N′-[( E)-2-chlorobenzylidene]- N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12ClN3O3, (II), (4 S)- N′-[( E)-4-chlorobenzylidene]- N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12ClN3O3, (III), and (4 S)- N′-[( E)-2,6-dichlorobenzylidene]- N,3-dimethyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C13H13Cl2N3O3, (IV), show that an unexpected mild-condition racemization from the chiral starting materials has occurred in (I) and (II). In the extended structures, the centrosymmetric phases, which each crystallize with two molecules ( A and B) in the asymmetric unit, form A+ B dimers linked by pairs of N-H...O hydrogen bonds, albeit with different O-atom acceptors. One dimer is composed of one molecule with an S configuration for its stereogenic centre and the other with an R configuration, and possesses approximate local inversion symmetry. The other dimer consists of either R, R or S, S pairs and possesses approximate local twofold symmetry. In the chiral structure, N-H...O hydrogen bonds link the molecules into C(5) chains, with adjacent molecules related by a 21 screw axis. A wide variety of weak interactions, including C-H...O, C-H...Cl, C-H...π and π-π stacking interactions, occur in these structures, but there is little conformity between them.
- Subjects
HYDROGEN bonding; STACKING interactions; METHYLIDENES; OXAZOLIDINES; CRYSTAL structure
- Publication
Acta Crystallographica Section C: Structural Chemistry, 2015, Vol 71, Issue 8, p647
- ISSN
2053-2296
- Publication type
Article
- DOI
10.1107/S2053229615012450