|dc.description.abstract||Direct C–H bond functionalization provides an efficient route by allowing the construction of C – C bonds directly from C–H bonds. In this dissertation, methods using first-row transition metals as catalysts for C–H bond functionalization have been developed. Furthermore, protocols for direct arylation via benzyne intermediates have been demonstrated.
A number of first-row transition metal salts such as nickel, cobalt, and manganese chlorides have been shown to catalyze deprotonative dimerization of acidic arenes. Five- or six-membered ring heterocycles as well as electron-poor arenes can be dimerized under oxygen atmosphere when tetramethylpiperidine or dicyclohexylamide bases are employed.
An auxiliary-assisted, copper-catalyzed fluorination of benzoic derivative β-C-H bonds has been developed. The method employs silver(I) fluoride as fluorinating reagent, copper(I) iodide catalyst, and N-methylmorpholine oxidant. By optimizing conditions, mono- or di-fluorination can be achieved selectively. The method provides an efficient alternative for preparation of aryl fluorides.
An efficient method for base-promoted direct C-arylation of arenes such as heterocycles, alkynes, phenols, and anilines has been demonstrated. Under basic conditions, a variety of arenes can be arylated by aryl halides and aryl triflates. A variety of functional groups, such as alkene, ether, dimethylamino, trifluoromethyl, ester, cyano, halide, hydroxyl, ketone, and silyl are tolerated. The reactions are carried out at mild temperatures and proceed via aryne intermediates. In addition, a general method for trapping aryl lithium intermediates with various electrophiles has been described. Furthermore, new reaction between phenols and aryl halides forming helicenes has been discovered.||