Studies On Arylation Strategies In Organic Syntheses With Diaryliodonium Salts

Recently,diaryliodonium salts have been widely employed in organic synthesis as arylating reagents characterized with eco-friendly,easy access and high selectivity.In this dissertation,we report our studies on the methodology of arylations by using diaryliodonium salts as electrophiles.Firstly,a simple method for synthesis of diaryl sulfones via a metal-free coupling of N,N'-disulphonylhydrazide with diaryliodonium salts was developed.In this arylation,N,N'-disulphonylhydrazide was used as an efficient and stable source of sulfonyl groups.Furthermore,an efficient synthesis of biphenyls was developed by a Cu?OTf?2-catalyzed direct arylation between an electron-rich arene and a diaryliodonium salt.The reaction went through a modified Friedel–Crafts reaction mechanism,in which Cu?OTf?2 served as both Lewis-acid catalyst and transition-metal catalyst to generate the aryl carbocation from the corresponding diaryliodonium salt.Then,a one-pot,three-component method for preparation of imines was developed by simply stirring the mixture of diaryliodonium salt with nitriles and1,3,5-trimethoxybenzene in the presence of Cu?OTf?2.By using this method,the highly steric imines were synthesized in high yields,that usually was a difficult work by using conventional method.Furthermore,the aromatic ring on the nitrogen atom is at the same side with 1,3,5-trimethoxybenzene.The special configuration is different from the construction of conventional imines.Next,a novel method for the synthesis of 3-iodoquinolines was developed by copper-catalyzed tandem annulation from diaryliodoniums,nitriles,and 1-iodoalkynes.Among the synthetic methods of quinolines,the introduction of a C3 substituent on the quinoline ring usually is much more difficult than that of C2 and C4 substituents.Recently,metal-catalyzed cross-couplings of aryl halides,such as Buchwald-Hartwig,Heck,Sonogashira,Suzuki,and Ullmann couplings,have been employed to efficiently synthesize C3-subtituted quinolines starting from 3-iodoquinolines.Thus,the importance of the synthesis of 3-iodoquinolines has been enhanced significantly.Finally,a novel tandem copper-catalyzed reaction of diaryliodonium salt with2-alkynylbenzonitriles was developed as an efficient method for the synthesis of isoquinolin-1?2H?-ones.In this raction,Cu?OTf?2 served as Lewis-acid catalyst to transform into Ar-Cu^III by diaryliodonium salts,and then activate nitrile and alkyne to promote the cascade process.