Exploring New Coupling Reactions Of Oxidative C-H Activation

With the emergence of the concepts of "atom economy" and "green chemistry",the cross-coupling for C-X(X =C,O,N,S,etc.) bond formation via transition metal-catalyzed C-H activation is a challenging subject.Oxidative C-H activation is superior to many other methods,for it avoids the using of expensive metal catalysts.Based on our research in the DDQ mediated activation of sp³ C-H of 1,3-diaryl-1-propene,we further investigated this cross-dehydrogenative-coupling(CDC) between 1,3-diarylpropene and other nucleophilic substrates.The formation of diarylallyl ether via the oxidative cross-coupling of 1,3-diarylallylic sp³ C-H bond and alcohols promoted by DDQ was developed by our group.This procedure provided a new highly efficient method to construct C-O bond.This system was also applied to form C-S bond from 1,3-diarylpropylene and thiols/thiophenolsOn the basis of above finding on cross-dehydrogenative-coupling of diarylaUyl sp³ C-H and alcohols/thiols,we have next explored the oxidative coupling of azoles to form C-C bond at the 2-position of azoles catalyzed by Cu(OAc)₂.Oxidative homo-coupling reactions of various azoles could all proceed smoothly under Cu(OAc)₂ catalysis using air as the oxidant.The coupling of different azoles could generate the corresponding cross-coupling products.The above two parts mainly involved the formation of C-C,C-O and C-S bond,which are difficult to construct by the traditional methods and could be directly realized with high efficiency via oxidative dehydrogenative-coupling reaction.In the view of the simplicity of the operation,short procedure,availability of the material and atom economical,the above procedures are very ideal methods for the concise and efficient synthesis of the corresponding compounds.