Synthesis of Hydroxysumanene and Substituent Effect of Hydroxy Group on Bowl Inversion Dynamics and Electronic Structure.

Hydroxysumanene was synthesized from acylsumanenes by Baeyer-Villiger oxidation. DFT calculation predicted the higher bowl inversion energy and deeper bowl structure of hydroxysumanene than those of pristine sumanene. The bowl inversion energy of hydroxysumanene was experimentally determined by 2D-EXSY NMR measurement as 21.2 kcal/mol. The energy was larger than that of pristine sumanene (20.3 kcal/mol), which agreed with the calculation result. Electrochemical measurement indicated the higher HOMO level of hydroxysumanene than that of sumanene, which confirmed the electron-rich character of the phenolic function in the bowl skeleton.