Activation And Transformation Of Aromatic C-N And C-O Bonds

This thesis is about activation and transformation of aromatic C-N and C-O bonds.We carried out the C-N bond cleavage of aryltrimethylammonium salts under transition-metal-free conditions and the C-N bond cleavage of 1-aryltriazenes in the presence of transition metal catalysts.We also performed cross-coupling of aryl 2-pyridyl ethers with aryl or alkyl zinc reagents under the catalysis of nickel.Chapter 1 presents transition-metal-free reaction of aryltrimethylammonium iodides with arylzinc reagents.The reaction can markedly promoted by MgCl₂ and LiCl.The reaction is suitable for a wide scope of substrates,covering electron-rich and electron-deficient electrophiles and nucleophiles.A range of functional groups including F,Cl,CF₃,COOEt,C?O?NEt₂,C?O?Ph,OMe,OPiv,NMe₂ and Py groups can be tolerated.Preliminary mechanism experiments reveal that the reaction may proceed via a free radical process.Chapter 2 describes arylation of?benzo?oxazoles with 1-aryltriazenes in the presence of tBuOLi under catalysis of palladium/CuCl/dppe.Electron-rich and electron-deficient 1-aryltriazenes were demonstrated to react with various oxazoles and thiazoles to afford the corresponding coupling products in moderate to high yields.In addition,a range of functional groups on the aromatic rings of 1-aryltriazenes or azoles including F,Cl,CF₃,COOEt,CN,OMe,NMe₂,Py and thienyl groups can be tolerated.Chapter 3 introduces the Ni?PCy₃?₂Cl₂-catalyzed cross-coupling reaction of aryl 2-pyridyl ethers with organozinc reagents.The reaction selectively occurs at the aryl C-O bond rather than the pyridyl C-O bond.The electron-deficient,electron-rich and sterically hindered aryl 2-pyridyl ethers can used as electrophiles.Various aryl zinc reagents can be used as nucleophiles.Functional groups such as F,CF₃,COOEt,C?O?NEt₂,OMe and NMe₂ groups can be tolerated.In addition,the catalytic system is also suitable for reactions with methyl and benzyl zinc reagents.Discovery of these reactions enriches the methods of activation and transformation of carbon-heteroatom bonds and extends the range of the electrophiles in the coupling reactions of C_sp2-C_sp2 bonds,providing more options for the organic synthesis reactions.