Efficient Synthesis Of Novel Benzofuran C-glycosides

Benzofuran derivatives exist widely in nature and are an important class of natural products.Some benzofuran derivatives have various biological activities,and some have been developed as drugs for clinical use to treat various diseases.Synthesis of new structural benzofuran derivatives to obtain biologically active compounds is one of the effective methods to discover lead compounds.In this paper,a novel and efficient synthesis method of benzofuran-type carbon glycosides was developed.At room temperature,five terminal sugar alkynes were used as raw materials to undergo Sonogashira coupling reaction with o-iodophenol with different substituents,and the intramolecular ring was closed to synthesize a series of novel structural carbon benzofuranosides.The synthetic method is easy to operate,has high yield,and has good substrate universality.The full text is mainly divided into the following four parts:1.The recent progress in the synthesis of benzofuran derivatives and the synthesis of sugar alkynes were reviewed.In the published literature,there are no synthetic studies of carbon benzofuranosides.2.Galactyne and o-iodophenol were selected as reaction substrates to synthesize the corresponding carbon benzofuranosides,and the reaction was used as a template to study the optimal conditions of the reaction.By optimizing the reaction conditions,such as the type and amount of palladium catalyst,the solvent used,the reaction temperature,and the ratio of substrate materials,the optimal reaction conditions were found.In the presence of 5 mol%Pd(PPh3)2Cl2 catalyst,anhydrous methanol was used as solvent,the molar ratio of galactyne and o-iodophenol was 1:1.1,and the corresponding benzofuranosides were obtained in 85%yield at room temperature.3.Under the optimal reaction conditions,five different types of sugar alkynes were reacted with o-iodophenol with different substituents,respectively,and 24 novel carbon benzofuranosides were synthesized with yields of 75-91%.The structures of these compounds were characterized by IR,1H-NMR,13C-NMR,DEPT-135,1H-1H COSY,HSQC,HMBC and HRMS.4.The formation mechanism of these carbon benzofuranosides was speculated.They are generated by Sonogashira coupling reaction and intramolecular ring closure.