Sythesis Of Oxazoles And Synthesis Of Oxindoles By Tandem Reaction

Oxazoles and oxindoles derivatives are a very important class of heterocycles widely found in many naturally occurring products and biologically active compounds, which displays potential utilizations in many major therapeutic areas, such as oncology, inflammation, CNS, immunology and endocrinology. Due to their broad range of bioactivities and pharmacological activities, considerable effort has been devoted to the development of new and efficient methods for their synthesis.Zinc-catalyzed synthesis of oxazoles is a very efficient and economical method. Traditionally, expensive transition metal catalysts, such as gold or palladium, are used for the synthesis of oxazoles. On the other hand, the tandem reaction is one of the most powerful synthetic tools for the rapid and efficient assembly of various cyclic and polycyclic structures. Notably, the palladium-catalyzed C-H activation reaction and amination have become the important methods for the formation of the carbon-carbon bonds or carbon-nitrogen bonds. The contents of this dissertation include zinc-catalyzed cyclization of propargylcarboxamides leadint to oxazoles and palladium-catalyzed C-H bond activation/annulation/amination tandem method for the selective synthesis of 3-(aminomethylene)-2-oxoindolines.1. A efficient and economical protocol has been developed for the synthesis of 2,5-disubstituted oxazoles. In the present of Zn(OTf)2 and air, a variety of propargylcarboxamides underwent the intramolecular annulation reaction to afford the corresponding oxazoles in moderate yields.2. A new palladium-catalyzed C-H bond activation/ aminopalladation tandem method was presented for the selective synthesis of 3-(aminomethylene)-2-oxoindolines. In the present of Pd(dba)2 (10 mol%), Xantphos (10 mol%), Ag(OAc) (2 equiv)、Na2CO3 (2 equiv) and oxygen, a variety of 3-Chloro-2-iodo-N-arylacrylamides derivatives underwent the domino reaction with amides or amines to afford the corresponding products in moderate to good yields at 50℃or 80℃temperature.