The Study Of Lewis Acid Catalyzed The Tandem Cyclization Reaction Of ?,?-Unsaturated Diketones And ?-Naphthol To Construct Functionalized 4H-Chromene Compounds

Chromene,also knowned as benzopyran,are important bicyclic compounds.Chromene derivatives always have two kind basic skeleton structures,2H-chromene and 4H-chromene,which are widely found in natural products and drugs.Because of its unique structure and pharmacological activity,4H-chromone derivatives are often used as antioxidants,antibacterial and anti-inflammatory drugs,antiviral drugs,anti-tuberculosis and anti-cancer drugs.Therefore,more and more chemistry researchers are interested in the way of the efficient synthesis of compounds containing 4H-chromene skeleton units.It can be seen from a large number of literatures that there are many ways to synthesize 4H-chromenes,but there are few reports on the synthesis of 4H-chromenes containing carbonyl groups.?,?-unsaturated di-ketone compounds are important raw material to construct the polycyclic compounds.2-Naphthol compounds are biphenyl compounds containing phenolic hydroxyl groups,in which the special structure makes them have larger polarity and higher activity of reaction.Based on the above findings,this article mainly studies the synthesis of4H-chromone derivatives 3a that combine 2-naphthol compounds 1a and?,?-unsaturated di-ketone 2a by using Sn?OTF?₂ as catalyst.Through a series of conditions?catalyst,solvent,type of alkali,temperature and ratio of raw materials?selection and optimization,the best condition of the reaction is seachered.The ratio of 2-naphthol 1a and?,?-unsaturated di-ketone 2a is 1.0:3.0,40 mol%Sn?OTF?₂ as catalyst,and the best reaction temperature is 60?.The method is simple and mild.Taditionally,amines were obtained by reducing nitro group.Since the unique structure of the target product 3a contains carbonyl groups,we wonder whether the C-H bond can take place amination by using carbonyl groups as the guiding groups.Based on the interest in the target products 3a and TsN₃,the 4H-chromene derivatives synthesized by this kind of reaction,so we use them as guiding groups to react with TsN₃ to achieve further derivatization.Due to the 4H-chromone with the carbonyl group,we use them as the guiding group to react with TsN₃ to realize further derivatization.We also screened and optimized the reaction conditions,and it was found that the most optimum conditions were including as follows:the ratio of4H-chromene derivative 3a with carbonyl group and TsN₃ b was 1.0:2.0,the catalyst is 7.5mol%[IrCpCl₂]₂,and 20mol%AgNTf₂and 1equivLi₂CO₃ and 1equiv CH₃COOH and DCE?2.0 mL?were entered.with magnetic stirring,the reaction time is 4 hours in the oil bath at 80?.At the same time,whole system does not need rare gas to protect.The advantage of the reaction is that the yield of the reaction is high,up to 93%,and its region-selectivity is stronger,and the experimental operation is simple.