名称:
A Novel Synthesis of Benzo[b]selenophenes via Regioselective Intramolecular Transformation of 4-(3-Nitroaryl)-1,2,3-selenadiazoles
摘要:
Base-promoted transformation of 4-(3-nitroaryl)-1,2,3-selenadiazoles via intermediate formation of eneselenolates followed by 5-exo-trig cyclization Is reported. The regiochemistry of the intramolecular cyclization is condition-dependent. In the presence of an oxidant, the oxidative nucleophilic substitution of the hydrogen (ONSH, SNArH) pathway, by oxidative aromatization of the rapidly formed sigma(H)-adduct, takes place. In the absence of oxidant, the reaction proceeds via intermediate formation of the sigma(Cl)-adduct, following nucleophilic aromatic substitution of the halogen (SNArCl) pathway.