Improvement in the process for preparing biaryl compounds via coupling of an arylamine with an arene in the presence of a nitrite, an acid and copper metal or a derivative thereof; the improvement is consisting in adding to the reaction mixture a trialkylorthoformate. The process may be used for preparing drugs such as Flurbiprofen and Xenbucin or intermediate compounds particularly useful for preparing Flurbiprofen, Flufenisal, Chlordimorin, Xenbucin, Xenysalate, Xenyhexenic acid and the like.