Palladium-catalyzed Site-selective Sp~3 Bond Thiocyanation Of 2-aminofurans And Photocatalytic Acetyl Arylation Of Alkenes

Alkyl thiocyanates and fluorenone skeletons are ubiquitous in drugs and natural products,a number of which features good physiological activity.Therefore,it is of great significance to develop new and highly efficient methods for the synthesis of alkyl thiocyanates and fluorenone derivatives.As such,this article has carried out the following two aspects of research work:1.Palladium-Catalyzed site-selective sp3 C-H bond thiocyanation of 2-Aminofurans.Using 2-aminofuran as raw material,Pd(OAc)2 as catalyst,Na2S2O8 as oxidant and NaSCN as thiocyanide source,direct thiocyanation of the 4-position substituent of 2-aminofuran sp3 C-H was realized,and the synthesis was achieved in one step.2-amino-4-thiomethylene acid methylene compound.Can be easily prepared in one step.The reaction conditions are mild,the substrate scopes are broad,featuring has better atom and step economy than conventional methods for preparing alkyl thiocyanates by nucleophilic substitution of thiocyanates with alkyl halides.This reaction represents the first example of transition-metal-catalyzed site-selective sp3 C-H bond thiocyanation,thus offering a novel strategy for the step-and atom-economic synthesis of alkyl thiocyanates.2.Photocatalytic acylarylation of unactivated alkenes with diaryliodonium salts toward indanones and related compounds.In this reaction,o-allylbenzaldehyde and diaryl iodonium salts were used as raw materials and Ir(ppy)2(dtbbpy)PF6 was used as a photocatalyst.White light was used as the light source to realize 2-benzylfluorenone and 2-benzyl in one step.Thus this provide an efficient route to synthesis of drugs or natural products containing fluorenone structural units,such as 3,4-dihydro-1-naphthalenone,2-benzyl-2,3-dihydro-quinolin-4-one,etc.The reaction proceeds at room temperature with medium to excellent yields and good substrate applicability.In particular,it should be noted that this reaction has excellent stereoselectivity and can selectively produce trans-2,3-disubstituted fluorenone.Although the bifunctional reaction of olefins has been well developed,this method is the first example of acetylarylation reaction for non-activated olefins and has a good research value.