Investigations Of Copper Catalyzed C-H Activation And N-Arylation Reactions

Nitrogen-containing organic compounds are very common on earth, most of which are bioactive and medicinal molecules. Amides and aryl amines are the most important two kinds of these compounds. Direct and selective formation of C-N bonds from unactivated carbon-hydrogen bonds is an important and long-standing goal in chemistry. These conversions have wide potential in synthetic organic chemistry because C-H bonds are ubiquitous in organic molecules. Developing novel and special ligands to promote copper-catalyzed Ullmann-type N-arylation reactions is the main strategy for the synthesis of aryl amines. Based on the important value of amides and aryl amines, in this dissertation, we aim to develop new synthetic strategies of these two kinds of compounds, and some important results are obtained as follows:We have developed a novel copper-catalyzed amidation of unactivated sp~3 C-H bonds adjacent to a nitrogen atom via cross-dehydrogenative-coupling reaction by using an inexpensive catalyst-oxidant (CuBr/tBuOOH) system under mild conditions. The dephenylation of N-benzylaniline first was disclosed, and the new products may provide diverse structures for pharmaceuticals and combinatorial chemistry.We have developed a new copper-catalyzed method for the amidation of benzylic and allylic sp~3 C-H bonds. The protocol uses CuBr as the catalyst and nonexplosive NBS and NHS as the oxidant, and the amidations were efficiently performed under mild conditions. The reactions are insensitive to atmospheric moisture and oxygen, and neither dried solvent nor an inert atmosphere is required. The catalyst-oxidant (CuBr/NXS) system is an inexpensive and convenient example for amidation of the unactivated C-H bonds.We have developed a new bidentate ligand, 2,2-bipiperidine, which shows high efficiency in copper-catalyzed Ullmann-type N-arylation reactions. This catalytic system can be successfully used in ayrlations of aliphatic amines, aryl amines and nitrogen-containing heterocycles. These cross-coupling reactions are of tolerance of various functional groups, and a large number of new aryl amines have been synthesized.