Sterically overcrowded alkenes; synthesis, resolution and circular dichroism studies of substituted bithioxanthylidenes
作者:Wolter F. Jager、Ben de Lange、Anne Marie Schoevaars、Fré van Bolhuis、Ben L. Feringa
DOI:10.1016/s0957-4166(00)80349-3
日期:1993.7
Bithioxanthylidenes with small substituents at positions 2 and 2' have been synthesized and resolved by chiral HPLC. The X-ray molecular structure of 9-(2'-methyl-9'H-thioxanthene-9'-ylidene)-9H-xanthene (17) confirms the folded form of these molecules. UV and CD studies of several bithioxanthylidenes are presented. The CD spectra of these molecules can be described qualitatively by subtracting the CD spectra of both differently sensed helices (M and P) present in the molecule, which can be distinguished by the substituents at positions 2 and 2'.