High-valent Iodine Reagents Involved In The Chlorination Reaction Study

Unlike other aromatic halides, aryl chlorides have a dichotomous function in the areas pharmaceuticals, natural products, imaging, agrochemicals and materials science. The presence of chlorine atom confers molecules with both function and functionalizability. Especially in the agrochemicals and drug discovery fileds, chlorination is usually motivated by a desire to enhance biological properties in a similar vein to fluorination. However, aryl chlorides stand alone in their nearly limitless potential for diversification using cross-coupling chemistry. So the development of new chlorination methodology has attracted great attention.Direct methods for aromatic C-H chlorination can be classified into three main modes:(1) electrophilic aromatic substitution (SEAr); (2) hydrogen-metal exchange; (3) transition-metal-catalyzed C-H activation methods. But some of them present drawbacks:for electrophilic aromatic substitution, where reagents can be too reactive, unselective, or, conversely, unreactive without the presence of strong electron-donating groups on the aromatic system. For hydrogen-metal exchange, which can be efficient and regioselective but requires the use of a strong base and a directing group. And transition-metal-catalyzed C-H activation methods are emerging as useful tools with regioselectivity that is often complementary to classical methods, though the substrate scope can be limited. In this communication, we present the application of 1-chloro-1, 2-benziodoxol-3-one, an age-old reagent, in the direct electrophilic chlorination of heterocycles and arenes. This hypervant iodine is easy preparation, post-reaction purification and recyclability. And the reaction shows broad group tolerance and substrate scope.Solvents are the only effect factor for this chlorination reaction. After studied the solvents, optimum reaction contions were established. Heterocycle (0.3 mmol,1.0 equiv) in anhydrous DMF (2 mL) at room temperature was added chlorinating reagent (0.36 mmol,1.2 equiv) and the mixture was stirred for 12 h under air condition to afford the product.