synthesis of dibenzofuran derivatives by catellani's strategy in one pot

Benzofuran derivatives are an important heterocyclic compounds that are possess vital biological activities such as antidepressant, anticancer, antiviral, antifungal, antioxidant, anti-psychotic etc. [1] substituted benzofurans also posses other applications such as fluorescent sensor, antioxidants, oxidant, brightening agents and in other field of chemistry and agriculture. benzofurans presents in various natural products with various physiological, pharmacological and toxic properties. due to the biological properties of benzofuran, there have been many reports of synthesis of this compounds in the last decade. [2] one of the attractive ways to synthesis of different compounds is to use catellani's strategy. [3] in this approach it is possible to functionalization two positions in a one pot. in this work, this strategy was used to synthesis of dibenzofurans. 2-iodotoulene derivatives have been used as a source of iodoarene. the reaction includes the ullmann type reaction and the arylation of ortho-position of aryl halide. thus, the process involves ullmann coupling to ipso-position, and c-h activation at ortho-position. the reaction is carried out in the presence of the palladium acetate as a catalyst and the triphenylphosphine as a ligand, and cesium carbonate as a base. in this reaction, two bonds are formed in one pot, include a c-o bond and a c-c bond. the reason for the use of norbornene in this reaction is the activation of c-h bond, which is common in the catalytic reaction. crucial to the mechanism of this reaction is the formation of palladacycle as an intermediate in the reaction in which c-h bond activation take place. so, this is a simple and economical way to synthesis of dibenzofuran.