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Conformational study of the 3,6‐dihydro‐2 H ‐1,4‐oxazin‐2‐one fragment in 8‐ tert ‐butyl‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]decane‐2,10‐dione stereoisomers
Author(s) -
Żesławska Ewa,
Jakubowska Anna,
Nitek Wojciech
Publication year - 2017
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229617009068
Subject(s) - chemistry , moiety , enantiomer , stereochemistry , decane , stereoselectivity , crystal structure , molecule , hydrogen bond , macromolecule , crystallography , organic chemistry , catalysis , biochemistry
Unnatural cyclic α‐amino acids play an important role in the search for biologically active compounds and macromolecules. Enantiomers of natural amino acids with a d configuration are not naturally encoded, but can be chemically synthesized. The crystal structures of two enantiomers obtained by a method of stereoselective synthesis, namely (5 R ,8 S )‐8‐ tert ‐butyl‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]decane‐2,10‐dione, (1), and (5 S ,8 R )‐8‐ tert ‐butyl‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]decane‐2,10‐dione, (2), both C 14 H 21 NO 4 , were determined by X‐ray diffraction. Both enantiomers crystallize isostructurally in the space group P 2 1 , with one molecule in the asymmetric unit and with the same packing motif. The crystal structures are stabilized by C—H…O hydrogen bonds, resulting in the formation of chains along the [100] and [010] directions. The conformation of the 3,6‐dihydro‐2 H ‐1,4‐oxazin‐2‐one fragment was compared with other crystal structures possessing this heterocyclic moiety. The comparison showed that the title compounds are not exceptional among structures containing the 3,6‐dihydro‐2 H ‐1,4‐oxazin‐2‐one fragment. The planar moiety was more frequently observed in derivatives in which this fragment was not condensed with other rings.