Studies Towards Transition Metal Catalyzed C-H Activation And Direct Functionalization

Recently, transition metal catalyzed C-H bond activation has attracted many attentions of chemists, due to its atom economy and high efficiency. The click type of reactions for the ring formation is one of the most effective ways of constructing useful heterocycles.The transition-metal mediated direct functionalization of arene at non-ipso position has been reviewed in Chapter 1. A number of new bond formation strategies have been discussed. Not only can the metal complex realize the para-functionalization, but also could aryl pyridines undergo metal complex intermediates to synthesize meta-functionalization under the catalytic amount of Ru.Ru catalyzed meta-bromination on arenes of 2-aryl pyridines have been described in Chapter 2. Aryl pyridines and NBS were used as subtrates, which were treated with Ru catalyst in DMA to synthesize a variety of meta-bromo products. The transformation involved pyridine-directed ortho C-H metallation followed by the Friedel-Crafts type of bromination and the elimination of the metal species.The synthesis of hydroxyl isoindolinones was reported in Chapter 3. Benzamides were carried out with aldehydes to prepare many kinds of desired products.The reaction was completed in 15 min for all the examples we have illustrated during our studies. Gram-scale synthesis using 1 mol% Pd catalyst was also successfully carried out. Hydroxyl group of isoindolinones could be substituted by aromatic rings to obtain diaryl isoindolinones Friedel-Crafts alkylation.As an alternative reaction pathway, the synthesis of biaryl carboxylic acids was also discussed in Chapter 4. This reaction was realized through adding Lewis acid-BF3.OEt2, which is very key for the migration of NOR group from amides to imines. The carboxyl acid group could be easily removed by Cu.Norbornene and its derivatives were tested in the functionalization on arenes as external directing group in Chapter 5. The prepared norbornene amides indicated the similar reactive activities as norbornene.