1. Hindered rotation in N-acyloxy-4-methylthiazole-2(3H)-thiones
- Author
-
Sabine Altermann, Thomas Gottwald, Georg Stapf, Jens Hartung, Christine Schur, Irina Kempter, Markus Heubes, and Uwe Bergsträßer
- Subjects
chemistry.chemical_classification ,Steric effects ,Cyclic compound ,Ketone ,Stereochemistry ,Carboxylic acid ,Organic Chemistry ,Substituent ,chemistry.chemical_element ,Biochemistry ,Sulfur ,Medicinal chemistry ,chemistry.chemical_compound ,chemistry ,Drug Discovery ,X-ray crystallography ,Single bond - Abstract
Experimentally determined barriers to O-acyl group topomerization in mixed anhydrides composed of β-disubstituted carboxylic acids and cyclic thiohydroxamic acid N-hydroxy-4-methylthiazole-2(3H)-thione were located in the range of ΔG‡320=68±8 kJ mol−1 (DNMR). According to modeling studies, the underlying exchange process is proposed to occur via rotation about the N,O bond for torsional movement of the O-acyl group past the heterocyclic 4-methyl substituent. The energetically lowest pathway for passing the O-acyl entity by the thione sulfur, is predicted to occur via sequential rocking about the C sp 2 ,O single bond in combination with an interlaced twist about the N,O axis.
- Published
- 2009