Rh(Ⅲ)-catalyzed Oxidative Olefination Of Aryl Carboxamides And NH Isoquinolines

Synthesis of complex organic structures via C-H activation pathway has emerged as an important strategy and has attracted increasing attention. Tremendous new synthetic methods have been developed using transition metals such as Rh, Ir, Ru, Pd, and Ni, which allow for facile access of both carbocycles and heterocycles from readily available starting material. This strategy is advantages in that C-H bonds are ubiquitous and minimal functionalization of starting materials is necessary, and both sp3C-H and sp2C-H bonds could be efficiently functionalized. Functionalization of C-H bonds under oxidative conditions via C-H activation pathway is more challenging, and limited progresses have been made.This thesis includes three chapters:Chapter 1: transition-metal-catalyzed oxidative olefination through C-H bond cleavage in organic synthesis. A wide variety of C-C bond forming reactions via C-H bond cleavages, as well as methods to control or improve the selectivity, which would be useful in organic synthesis, remain to be achieved.In part one, oxidative olefination has been achived by transistion metals (such as Rh and Pd) catalysis.Chapter 2: Rh(III)-catalylzed tandem oxidative olefination-Michael reaction between aryl carboxamides and alkenesThis thesis reports two systems of Rh(III)-catalyzed oxidative olefination of arene C-H bonds. In chapter two, ortho C-H bonds in the carboxylic acid ring of N-alkyl and N-aryl substituted benzamides was successfully and selectively activated and were functionalized by olefins to give five-membered lactam. This reaction occurred via an oxidative olefination-Michael reaction sequence using Rh(III) catalyst and Ag(I) oxidant. A broad substrate scope has been studied. In particular, when heterocarboxamides were used, oxidative olefination products and/or final lactam products have been isolated depending on the nature of the heterocycles.Chapter 3: Oxidative coupling of NH isoquinolones with olefins catalyzed by Rh(III)In Chapter 3, NH isoquinolones were synthesized and were used as starting materials for C-H activation. NH isoquinolones bearing aryl groups at the 3-position readily undergo C-H activation in the ortho position of the 3-aryl ring. Using [RhCp*Cl2]2 as a catalysts and cheap Cu(OAc)2 as an oxidant, oxidative olefination was achieved. Similar to the reaction products obtained in chapter one, the final products are 5-membered N-containing heteroycles. More importantly, this coupling reaction can be one-pot starting from PhC(O)NH(OMe) and alkynes. The mechanism of this coupling process has been discussed. A broad scope of substrates have not been demonstrated. While the coupling with terminal alkynes may follow anolefination-Michael addition sequence via a Heck-like mechanism, internal olefins are proposed to react via a Wacker-like mechanism, with backside attack of amide functionality on metal-bound alkene being a key step.