New Methods For The Construction Of Oxygen-and Nitrogen-containing Skeletons From Double Or Triple C-C Bonds

Nitrogen and oxygen are the basic elements of organic compounds.Organic molecules containing oxygen or nitrogen functional groups have been widely used in organic synthesis,drugs,dyes and other fields.The introduction of heteroatoms can improve the physical properties and chemical activities of the compounds.So the innovative research of introducing nitrogen,oxygen and other heteroatoms into molecules has been the goal of chemists by simple,mild and green methods.It has always been favored by chemists using a large number of double or triple C-C bond organic compounds which provide natural world and petrochemical production as raw materials to construct containing oxygen-and nitrogen-containing organic skeletons under mild conditions.In recent years,with the appeal of human society for sustainable development,it has become a research hotspot of organic chemistry to realize the traditional thermal reaction which requires harsh conditions by visible light irradiation at room temperature.Under the background that our group continues to carry out visible light driven organic transformation,we have developed several simple,efficient and green catalytic systems to directly construct oxygen-and nitrogen-containing organic skeletons from double or triple C-C bonds as raw materials under ambient temperature.Meanwhile,the mechanism of the reaction is also discussed.This paper mainly includes the following four aspects:1.Recent researches are reviewed in the field of vinyl azide-mediated reactions and visible-light driven alkyne oxidation.In this section,we summarized the plausible pathways of vinyl azides in organic transformations and the reactions categorized by catalysts and conditions such as transition metals,acids,bases,triphenylphosphines and visible light.In addition,the visible-light driven oxidation of alkynes is also discussed briefly.2.We reported that visible-light driven synthesis of 4?alkyl/aryl-2-aminothiazoles derivatives could be accomplished by in situ generated copper photocatalyst which is formed by Cu（OAc）₂and NH₄SCN.Mechanism investigation indicates that in situformed Cu（NCS）₂^-plays dual important roles in the reaction:（1）as the photocatalyst to activate vinyl azides,（2）as the Lewis acid catalyst.This process is distinguished by high yields,mild conditions,low catalyst loadings,and tolerating numerous alkyl-and aryl vinyl azides with an array of functional groups.3.Eosin Y is a commonly organo-photocatalyst,but it is seldom known the thermal reactions are catalyzed by eosin Y.Recently,we the first reported a co-catalytic system of eosin Y/Cu（OAc）₂ without light irradiation to synthesize eneγ-lactam which are widely used to construct the key skeletons of important active natural products and related drug intermediates.Moreover,the possible reaction mechanism is discussed.4.Alkynes are stable and readily available organic compounds.We have developed a method to directly oxidation of alkynes to form cation radical by organic dye as photocatalyst under visible light irradiation.Then the cation radical react with simple alcohols to form benzoin di-ether compounds at room temperature.It is a green and sustainable synthesis strategy to use oxygen in air as oxygen atom source and oxidant,water as by-product in this reaction.