X‐ray crystallographic structure of a novel enantiopure chiral isothiourea with potential applications in enantioselective synthesis

• Published in: Acta crystallographica. Section C, Crystal structure communications Crystal structure communications, 2024-01, Vol.80 (1), p.15-20
• Main Authors: Savin, J. Alejandro, Ávila-Ortíz, C. Gabriela, Leyva-Ramírez, Marco Antonio, Juaristi, Eusebio
• Format: Article
• Language: English
• Subjects: asymmetric organocatalysis; chiral diamine; chiral isothiourea; Crystal structure; Crystallography; Crystals; Enantiomers; enantiopure; halogen bond; resolution; Stereoselectivity; Synthesis
• ISSN: 2053-2296; 0108-2701; 2053-2296; 1600-5759
• DOI: 10.1107/S2053229623010781

The synthesis of a chiral isothiourea, namely, (4aR,8aR)‐3‐phenyl‐4a,5,6,7,8,8a‐hexahydrobenzo[4,5]imidazo[2,1‐b]thiazol‐9‐ium bromide, C15H17N2S+·Br−, with potential organocatalytic and anti‐inflammatory activity is reported. The preparation of the heterocycle of interest was carried out in two high‐yielding steps. The hydrobromide salt of the isothiourea of interest provided suitable crystals for X‐ray diffraction analysis, the results of which are reported. Salient observations from this analysis are the near perpendicular arrangement of the phenyl ring and the mean plane of the heterocycle. This conformational characteristic may be relevant with regard the stereoselectivity induced by the chiral isothiourea in asymmetric reactions. Furthermore, evidence was found for the existence of an S…Br− halogen bond. The X‐ray crystal structure of a novel enantiomerically pure chiral isothiourea is reported. This compound offers potential applications as an organocatalyst.