| As one of the frontier areas in the research of metal organic chemistry, transition metal catalyzed cross-coupling reactions provide a powerful method for the construction of carbon-carbon bonds and carbon-heteroatom bonds. In recent years, the oxidative coupling reaction between two nucleophile has attracted more and more attention, and has made rapid development. From the first generation to the third generation of the development process of oxidative coupling reaction, the organometallic nucleophile is gradually replaced by the C-H or X-H (X= N, P, O, S, etc.) compound, which is the basic requirement of modern organic synthesis such as green chemistry, high atom economy and so on. Nowadays, the radical oxidative coupling reaction which contain a single electron transfer process, is one of the research hotspot in the oxidative coupling reaction, and is full of opportunities and challenges.In this thesis, the development of transition metal catalyzed radical oxidative coupling reactions was reviewed firstly. Then several typical types of this reaction was surveyed in details. The research work of this thesis was focused on the silver and copper mediated or catalyzed novel C-C and C-P bond forming reactions. At the same time, with many advanced instruments, such as in-situ IR, Raman, EPR, the mechanism of the reaction was studied, and the important role of free radical intermediates in the process of radical oxidative coupling reaction was revealed. Details are as followings:1. On the basis of previous work, a novel silver-mediated highly selective oxidative C-H/C-H Cross-Coupling/Cyclization reaction of ?-enamine esters with terminal alkynes was successfully developed. Through the radical addition and cyclization process between the P-enamine ester radical and alkyne, a series of poly-substituted pyrrole compounds were synthesized in one step. This method is simple, general, and efficient. At the same time, the study of mechanism further validated the key role of silver acetylide for restraining the homo-coupling reactions of the terminal alkynes. This method has important research value and application value in the construction of the poly-substituted pyrrole compounds.2. In order to solve the problem of using equivalent inorganic salt as oxidant, a novel copper catalyzed carbon-carbon bond activation of the ?-enamine esters was successfully realized under the oxygen atmosphere. Through the rearrangement and oxidative decarboxylation process of the ketone intermediate generated from the reaction of ?-enamine ester radical with oxygen, a series of a-imine esters were synthesized in one step. The reaction takes oxygen as an ideal oxidant and has no pollution. A novel and effective method for carbon-carbon bond activation is provided.3. Base on the design concept of radical/radical coupling, a new type of copper catalyzed radical oxidative Csp3-H/P-H coupling reaction of 0-acetyl aryl ketone oxime with diaryl phosphine oxides has been successful developed. This transformation offered a new protocol for Csp3-P bond formation by direct coupling of the carbon radical with phosphorus radical. a-Csp3-H bond activation was achieved directly without the assistance of active group such as ester group. On the other hand, the substrate is directly used as an inner oxidant, without the addition of other oxidants, which greatly reduces the cost of the reaction. This method is general, and efficient, which provides a model for the oxidative radical/radical coupling.4. From the understanding of the C-H bond activation via radical process in the the above works, a transition metal copper and small organic molecular amine co-catalyzed oxidative coupling reaction of simple aryl ketones and diaryl phosphine oxides has been further developed. This work offers a simple way toward ?-ketophosphonates by a-phosphorylation of simple aryl ketones. The reaction used the most raw materials with low cost and higher atomic economy. It provides a supplement to the mode of the oxidative radical/radical coupling. |
PDF Full Text Request