Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• . The study of the optimization conditions showed that the highest yields of products were obtained when: (I) in case of path A, 1.0 mmol of the 2,2-dimethyl-4-phenyl-2H-imidazole 1-oxide (9a) was reacted with pentafluorophenyllithium (13) (which was formed in situ from pentafluorobenzene (12)] in the

• presence of 1.0 mmol AcCl as eliminating agent (EA) in dry THF as solvent at −78 °C; (II) in case of path B, the mixture of 1.0 mmol of 2,2-dimethyl-4-phenyl-2H-imidazole 1-oxide (9a) and 1.0 mmol of pentafluorobenzene (12), 1.1 mmol of n-BuLi as base, 1.5 equiv DDQ as oxidant in dry THF as solvent was

• refluxed for 4 h. The screening of several 2H-imidazole 1-oxides revealed that the derivatives of 2H-imidazole 1-oxide reacted with pentafluorophenyllithium to provide the expected products in good yields (64–76%) regardless of the presence of either electron-withdrawing or electron-donating groups at the

Transition metal-free oxidative and deoxygenative C–H/C–Li cross-couplings of 2H-imidazole 1-oxides with carboranyl lithium as an efficient synthetic approach to azaheterocyclic carboranes

• Lidia A. Smyshliaeva,
• Mikhail V. Varaksin,
• Pavel A. Slepukhin,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2018, 14, 2618–2626, doi:10.3762/bjoc.14.240

• cross-coupling reaction of 2,2-dimethyl-4-phenyl-2H-imidazole 1-oxide (1a) with carboranyllithium 2 was chosen as a model reaction. It has finally been found that the best yield of 4a is achieved using AcCl as a deoxygenative agent at room temperature with stirring of the resulted reaction mixture for

• reaction of 2,2-dimethyl-4-phenyl-2H-imidazole 1-oxide (1a) with carboranyllithium 2. The experiments performed have shown effects of the used oxidants, temperature regime, and exposure time after addition of an oxidant into the reaction mixture. As a result, the optimal conditions have been found to

• -imidazole 1-oxide fragment is disordered into two positions with occupancy coefficient of 0.8/0.2. The minor disordered moiety has been confirmed to be in the (S)-configuration. Also it is worth mentioning that no shortened contacts have been observed in the crystals. Conclusion The direct C(sp2)–H