Synthesis Of C3 Functionalized Chromones By Tandem Annulation Of Enaminones

Chromone is a class of oxygen-containing heterocyclic compounds that was extensively found in natural products.Among them,C3 functionalized chromones have attracted great attention in the field of organic synthesis due to their unique physiological activity and chemical reactivity.As such,the development of efficient and simple strategies to obtain various C3 functionalized chromones is highly desirable.In recent years,enaminones have been proved to be reliable,inexpensive and easily available synthons for the construction of C3 functionalized chromones by the direct tandem annulation.In this research,the synthesis of C3 oximation and amination of chromone are realized from enaminones respectively under mild and green conditions.This thesis is divided into two aspects:1)As versatile building blocks,oxime compounds are widely used in the construction of fine chemicals and bioactive molecular modules.Herein,an efficient divergent synthetic route with tert-butyl nitrite as the oxime source has been developed for the direct oximation of enaminones without the addition of metal catalyst and other oxidants.The starting materials and reagents used in this strategy are inexpensive and easily available.Various C3 oximated chromanones and coumaranones derivatives were obtained with moderate to high yields under the simple manipulation.In addition,the scale-up reaction can proceed smoothly,and the obtained products can also be easily derived and transformed into a variety of small molecular compounds with potential drug activity.2)The introduction of nitrogen-containing groups into heterocycles can greatly change their physiological and functional properties of substrates in pharmaceuticals and medical materials.In this thesis,the direct C-H bond amination of enaminones has developed under photocatalytic conditions.Various nitrogen-containing heterocycles such as benzotriazole are introduced into the C3 position of chromone for the first time.By the formation of electron-donor-receptor complex in this process,a series of C3 aminated chromones are synthesized in moderate yield without the addition of photocatalyst and other additives,which widely broaden the application value of enaminones in the field of photochemistry.