Enantioselective organo-SOMO activation enables radical based functionalization of carbonyl compounds.

Five isatin anions were prepared by deprotonation of initial isatins in aprotic solvents using basic fluoride and acetate anions (F⁻ and CH₃COO⁻). The F⁻ basicity is sufficient to deprotonate isatin NH hydrogen from all the studied compounds. This process is reversible. In the presence of proton donor solvents, the anions form the corresponding isatins. The isatin hydrogen acidity depends on the overall structure of the isatin derivatives. The anions were characterized by ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Interestingly, the anions form aggregates at concentrations above 10⁻³ mol·dm⁻³. Further, the effect of cations on the UV–Vis spectra of the studied anions was studied. Charge transfer and its distribution in the anion depends on the radius and the cation electron configuration. The alkali metal cations, tetrabutylammonium (TBA⁺), Mg²⁺ and Ag⁺, interact with the C-2 carbonyl oxygen of the isatin anion. The interaction has a coulombic character. On the other hand, Cd²⁺, Zn²⁺, Hg²⁺, Co²⁺, and Cu⁺ cations form a coordinate bond with the isatin nitrogen.

The subject of this work was the study of thermally and photochemically stimulated Z ↔ E isomerization and hydrazo ↔ azo tautomerism of Z- and E-isomers of isatin arylhydrazones and ((arylamino)methylene)indolin-2-ones and their anions. Using NMR, UV-Vis spectroscopy, kinetic measurements, and HPLC, we studied the relationship of structure, (Z- and E-isomers), of these compounds and hydrazo=azo tautomerism. The ON/OFF functionality of these compounds and their anions using light to stimulate switching between ON and OFF states was investigated. We pointed out the characterization of the effect of =N- and =CH- structural fragments and aryl structure on ON and OFF states of isatin arylhydrazones and ((arylamino)methylene)indolin-2-ones.

The reactivity of aldehydes and ketones in asymmetric organo-SOMO reactions with enol silanes was explored. The best results were obtained with 3-phenylpropanal and tetralone-derived silyl enol ether and silyl ketene thioacetal.

The photoswitching behaviour of isatin 4-nitrophenylhydrazones in presence of anions was investigated.