1309381-71-2Relevant academic research and scientific papers
Synthesis, isolation, and skeletal inversion of 5,10-dihydrophosphanthrenes
Uchiyama, Yosuke,Mazaki, Yasuhiro
, p. 822 - 825 (2011/06/27)
Two stereoisomers, the trans form 1a and the cis form 1b, of 2,3,7,8-tetramethyl- 5,10-diphenyl-5,10-dihydrophosphanthrene dioxide (1) were formed by spontaneous oxidation in air of the corresponding 5,10- dihydrophosphanthrenes 2 and were separated by recrystallization. Both 1a and 1b were characterized by X-ray crystallographic analysis, which revealed configurations at the phosphorus and conformations of the central tricyclic system. The 31P NMR of the reaction mixture showed at first two signals at-15.3 and-15.1 ppm, which shifted to 9.11 and 10.3 ppm after purification of the reaction mixture under aerobic conditions by oxidation of phosphorus atoms. The reaction of 1b with HSiCl3 in toluene-d8 at 100 °C gave no change, whereas 1a reacted with HSiCl3 to give reduced compounds 2a and 2b under the same conditions. The trans-cis isomerization of 2 occurred via vertex inversion at phosphorus atom. VT-NMR, X-ray analysis, and density functional theory (DFT) calculation showed that the conformational exchange of the cis form 1b proceeded via skeletal inversion of the tricyclic ring. Copyright Taylor & Francis Group, LLC.
