C(2) and C(5) Nucleophilic Functionalization of 4 H -Imidazole-3-oxide Exposed to Carboranyllithium

The dual reactivity of 5-aryl-4H-imidazol-3-oxides with respect to carboranyllithium has been studied. In particular, in the presence of an oxidizing agent, the reaction of nucleophilic substitution of hydrogen by the mechanism of addition-oxidation (SNH AO) occurs with yields of up to 95%. On the other hand, in the absence of an oxidizing agent, the nucleophilic addition (AN) processes take place with yields of up to 60% at C(5) and C(2) carbon atoms of the imidazole ring, with predominance of the C(5) products in the case of ortho-carboranillitium, and C(2) in the case of 1-phenyl-ortho-carboranillitium. The behavioral characteristics of the AN reaction were studied using quantum chemical calculations and the reaction energy diagram. In addition, in the case of N-oxide derivatives, a mild light-induced transformation was found to yield oxaziridine cyclic structures characterized by enhanced thermal stability. The obtained data on the reactivity of nonaromatic imidazole systems toward carboranyllithium are of interest in the design of advanced hybrid organic-inorganic functional materials.