Theoretical Studies Of The Mechanism Of Synthesis Of Nitrogen-containing Heterocyclic Compounds Catalyzed By The Transition Metals

In recent years, organic azides participate in transition metal catalyzed reactionsthat construct new C-N, N-N and N-O bonds, which is a late-model area of intenseresearch interest by the synthetic community. Although there are some metalcomplexes have been reported for catalytic formation of these new bonds from vinylor aryl azides by experimental observation, the true mechanism details remainsinconclusive from viewpoint of theory. In this paper, we set out to investigate thereaction mechanism of transition-metal-catalyzed routes for the formation of C-N,N-N and N-O bonds with the aid of DFT calculations at the B3LYP level. Our hope isthat a systematically study of the factors influencing the mechanism ofmetal-catalyzed these new bonds formation reactions will lead to a fundamentalunderstanding of these factors that will assist experimental efforts in finding bettercatalysts.In Chapter3, we carry out a systematic DFT study to examine the isomerizationof2-aryl-2H-azirines to2,3-disubstituted indoles by FeCl2and Rh2(O2CCF3)4. Theresults indicate that the isomerization of2-aryl-2H-azirines mainly proceeds through astepwise mechanism and the Rh2(O2CCF3)4exhibits higher catalytic performance thanFeCl2. Investigation of the magnetic properties suggests that the C–N bond formationstep is pseudoelectrocyclization for the FeCl2-catalyzed system. The calculationsshow that a water-catalyzed1,2-H shift for the FeCl2-catalyzed system adopts aproton-transport catalysis strategy, in which chlorine atom coordination to the ironcenter is critical because it acts as a proton acceptor. When a molecule of water isinvolved in the Rh2(O2CCF3)4-catalyzed reaction, the1,2-H shift is significantlypromoted, so that the rate-determining step becomes the ring opening of2-aryl-2H-azirine. In addition, we studied the catalytic activity of Fe(OAc)2and CuCl. In Chapter4, we study the reaction mechanism for2H-indazole formation fromaryl azide catalyzed by CuI has been theoretically studied by DFT calculations.Various activation modes for the azide group were investigated, and it was found thatthe azide group is activated through the Cu(μ-I)2Cu(TMEDA) dimer coordinating tothe N-atom of phenyl imine and the internal N-atom of azide.