"Novel Transition Metal-Catalyzed Methods for Synthesis and Functionalization of Arenes and Heteroarenes"
We have developed a set of novel efficient transition metal-catalyzed methodologies for synthesis of multisubstituted carbo- and heterocycles [1-7]. Commonly, regioselective synthesis of carbo- and heterocycles possessing various functional groups is not a trivial task. We have shown, however, that incorporation of migrating step(s) in the cyclization cascade often helps solving this problem. Thus, it was found that in the presence of Cu-, Ag-, and Au catalysts, a number of groups, such as Hal-, RS-, AcO-, TsO-, Ar-, and SiR3 could undergo 1,2- or 1,3-migration, or in some cases even double migration, which allows for expeditious synthesis of densely-functionalized carbo- and heterocycles, which are not easily accessible via existing techniques. We have also explored a direct Pd-catalyzed C-H functionalization approach toward synthesis of multisubstituted aromatic and heteroaromatic molecules [8-11]. Thus, a novel silicon-tether approach for the Pd-catalyzed C-H arylation of phenols has been developed. Next development involved employment of the PyDipSi-, a Si-tethered directing group in the Pd-catalyzed C-H acyloxylation and halogenation reactions. The PyDipSi group is traceless or can easily be converted into a variety of useful functionalities. The scope of these transformations will be demonstrated and the mechanisms will be discussed.