142472-89-7Relevant academic research and scientific papers
Resolution of sterically overcrowded ethylenes; a remarkable correlation between bond lengths and racemization barriers
Feringa, Ben L.,Jager, Wolter F.,De Lange, Ben
, p. 2887 - 2890 (1992)
The synthesis and resolution of 2-methyl-9H-thioxanthene-9-(9H-thioxanthen-9-ylidene) 1 and related structures 2-5, being the first examples of thermally stable optically active sterically overcrowded ethylenes, are reported. Substitution of the sulfur atom in the thioxanthene part of 1 with an X group (2, X = C(CH32; 3, NCH3 4, O) results in a change in racemization barrier (1, 27.4 kcal.mol-1; 3, 21.3 kcal.mol1 4, -1) depending upon the aryl-X bond lengths.
