A Methodology Study On The Synthesis Of Novel Oxygen-containing Heterocyclic Compounds Based On Rhodium Catalysis

Oxygen-containing heterocyclic compounds are a class of heterocyclic compounds with important biological and chemical significance.Xanthone and its derivatives are bioactive organic compounds with great potential in medicine and fluorescence probe.Most of the existing methods for the synthesis of xanthone have some disadvantages,such as poor tolerance of substituents,harsh reaction conditions,difficult access to raw materials,etc.Therefore,it is of great importance to find new methods for the synthesis of xanthones.In the process of constructing these types of compounds,the functionalization of aromatics is a very important aspect.The α-imino rhodium(II)carbene complex formed from N-sulfonyl-1,2,3-triazole is an important active intermediate.Due to its good reactiveness,it has been used to synthesize novel heterocyclic compounds of great biological significance.Various conversion methods of α-imino rhodium(II)carbene complexes formed by N-sulfonyl-1,2,3-triazole are also considered to be important ways to achieve arene functionalization.In this work,a simple,mild and controllable method for the synthesis of xanthone from N-sulfonyl-1,2,3-triazole compounds catalyzed by rhodium(II)was developed for the first time.16 xanthone derivatives with different substituents were synthesized in excellent yields,which proved that the method has good substitution tolerance.In addition,the existence of tetracyclic intermediate during the reaction was confirmed by high-resolution mass spectrometry,high-performance liquid chromatography and nuclear magnetic analysis of the mixture.Based on this,the annulation/oxidation mechanism of the reaction was explained.The pure product of the new tetracyclic compounds was obtained in the presence of specific substituents.The tetracyclic compounds we synthesized are heterocyclic compounds with3,4-fused dihydroindole structure,which also have important biological significance.Xanthones and the new tetracyclic compounds synthesized in this work have important application prospects in medicine and biology.The efficient and mild method of aromatics functionalization developed in this work also provides an alternative pathway for the synthesis of more heterocyclic compounds in the future.