Study On Synthesis Of Nitrogen-and Oxygen-Containing Heterocyclic Compounds Via Ruthenium-Catalyzed Dehydrogenation Of Alcohols

Nitrogen-and oxygen-containing heterocyclic compounds constitute two kinds ofimportant substances among heterocycles, besides that, most of them have special biologicalactivity and pharmacological activity. As the intermediates of biology, agriculture, medicine,dye and other chemical products, they play important roles in human production and daily life.As a result, it is essential to develop an efficient, convenient, green and sustainable syntheticmethods to access new nitrogen-and oxygen-containing heterocycles. A large number ofalcohols represent as a class of abundant，cost-effective，easily-available and renewableresources，the project on effective utilization of alcohols and converting them into valuablenitrogen-and oxygen-containing heterocycles would be of significant importance. Therefore,the work described in this thesis focused on respectively synthesis of benzoxanthenes,multisubstituted pyrroles and2-arylquinolines via ruthenium-catalyzed dehydrogenation ofmonohydroxyl alcohols and diols.Initially, this thesis studied on primary alcohols employed for dehydrogenative synthesisof14-substituted-14-H-dibenzo[a,j]xanthenes. After optimization of reaction conditions, wefound an efficient catalyst system [P^O]2Cl2Ru/Yb(OTf)3[P^O=2-(diphenylphosphino)-2,4-di-methylpentan-3-one], both alkyl alcohols and aromatic alcohols could react smoothly andgave good product yields. This represented method compared with the traditional methods hasthe advantages of high selectivity, wide substrate and less by-products.Secondly, this paper studied the reaction of ruthenium-catalyzed dehydrogenation ofvicinal diols to react with β-aromatic ethylamine, providing a green, convenient and efficientmethods to synthesize multisubstituted pyrrole derivatives. Under the optimal catalytic system[RuCl2(p-cymene)]2/BINAP [BINAP=2,2’-Bis(diphenylphosphino)-1,1’-binaphthy],β-aromatic ethylamine with different substituents could also afford the corresponding pyrroles.On the basis of the findings, we also analyzed the basic raw of this reaction and its possiblemechanism. Moreover, this synthetic method is an important supplement to the synthesis ofmultisubstituted pyrroles.Finally, we have established a new method for the synthesis of2-aryl quinolines viaruthenium-catalyzed dehydrogenation of o-aminophenyl methanol with terminal aryl alkynes.The reaction just requires catalytic amount of [RuCl2(p-cymene)]2and AgOTf, which has themerits of mild reaction conditions, easy operation and purification procedure without theaddition of ligands. Owing to the aryl groups ortho to the nitrogen atom in the obtainedproducts, it provides the new optional space for the preparation of various cyclometallatedcomplexes.