Semeniuchenko V. Homogeneous Hydrogenation of Flavonoids and Electron-Deficient Alkenes by Using Iridium-Complexes

It was shown that it is impossible to hydrogenate flavonoids homogeneously in conditions applicable for the other substrates. Using 7-methoxisoflavone a new reaction of nucleophilic hydrogenation was discovered, which was catalysed by Ir-complexes in presence of DIPEA. Complexes of type [Ir(COD)(Phox)]BARF were synthesized avoiding difficult purification of the ligand. Their structure was proven by excessive assignment of the signals in NMR spectra. Six complexes, active in nucleophilic hydrogenation, were found. The applicability of reaction for the other electron-deficient alkenes was shown. The mechanism was proposed that suggests the formation of active particle which attacks soft electrophilic site of substrate (proven by DFT-computations). The inertness of several substrates was explained. Homogeneous hydrogenation of 3- and 2-(2-pyridyl)-7-methoxychormone (in electrophilic conditions) was studied. The hydrogenation of the latter compound proceeded asymmetrically.