Synthesis, Chiral Separation, Barrier to Rotation and Absolute Configuration of N-(O- Functionalized-Aryl)-4-Alkyl-Thiazolin-2-One and Thiazoline-2-Thione Atropisomers

The synthesis of N-(o-aryl)-4-alkyl-thiazolin-2-one atropisomers bearing hydroxy-, methoxy-, amino- or isothiocyanato- groups as ortho-substituent are described from their thiazoline-2-thione analogues. The enantiomers were obtained optically pure by semi-preparative chiral HPLC, their optical properties and absolute configurations were established. The barriers to rotation were determined and are discussed according to the nature of the substituents.