Synthesis Of Acyl Pyrazine Derivataves Based On Silver Catalyzed C-H Bond Activation

Pyrazines are heterocyclic aromatic rings with two nitrogen atoms located in the 1 and 4 position of the heterocycle.Pyrazines derivatives are are widely present in organic synthesis,medicinal chemistry,material science as well as food chemistry.The wide usefulness ofpyrazines derivatives has resulted in the development of synthetic methodologiesto construct them.However,many different synthetic approaches for pyrazinesderivatives often required multi-steps which seriously restrictedthe development and industrialization of new pyrazine compounds.On the other hand,transition metal catalyzed C-H bond activation hasemerged as powerful method in the field of organic synthesis due to the fact thatproducts always can be obtained in highly concise procedure.Thus,directfunctionalization of C-H bond has received continuous attention and witnessedsignificant progress.However,the study on the synthsis of new pyrazines flavorvia C-H bond functionalization has not been reported.For this reason,we intend tosynthesize a family of acyl substituted pyrazine derivatives via the direct C-H bond functionalization.In this thesis,we have developed a novel method for the direct synthesis of 2-acylpyrazines through silver-catalysis(Scheme 1).10 mol% of silver phosphate was used as the catalyst,0.4mmol potassium persulfate as the oxidant,a mixed solution of water(1.4ml:0.6ml)and methylene chloride as a solvent,finally,a series of 2-acyl-substituted pyrazine derivatives was obtained in moderate to excellent yield.This reaction features on mild conditions,short steps,atoms-economical,environmentally friendly and high regioselectivity.This methodology provides a new,simple and efficient processesfor the synthesis of pyrazines.According to the obtained results as well as the reported literatures,the reaction mechanism was speculated and shown in(Scheme 2).Scheme 1.Silver catalyzed acylpyrazine synthesis methodScheme 2.Reaction mechanism research...