Resolution of sterically overcrowded ethylenes; a remarkable correlation between bond lengths and racemization barriers.
作者:Ben L. Feringa、Wolter F. Jager、Ben de Lange
DOI:10.1016/s0040-4039(00)78887-3
日期:1992.5
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
Fast synthesis and redox switching of di- and tetra-substituted bisthioxanthylidene overcrowded alkenes
作者:Brian P. Corbet、Marco B. S. Wonink、Ben L. Feringa
DOI:10.1039/d1cc03098a
日期:——
A rapid and efficient method for the synthesis of overcrowded alkenes using (trimethylsilyl)diazomethane provides a range of substituted bisthioxanthylidenes. We show large conformational redox switching from folded to orthogonal states, which tolerates many substitution patterns. The facile access to bisthioxanthylidene switches with the potential for further functionalization, in combination with