Study On The Synthesis Of Thiochromeno[2,3-b]Indoles By Using Isothiocyanates

The indole derivatives are heterocyclic compounds usually found in bioactive natural products. Many aspidospermine, yohimbine, and strychnine molecules show potential biological and pharmacological activities of antibacterial, antiallergy, anticancer, antihyperplasia, anti-HIV. In recent years, more researches on 2,3-fused polycyclic indole derivatives have been done. Meanwhile, the 2,3-fused polycyclic indole derivatives generally have many aromatic rings with electronic conjugated distribution. The compound containing many aromatic rings has excellent thermal stability, change of electron, fluorescence, optical activity and so on. It is also applied in organic field-effect transistors(OFETs) and organic light emitting diodes(OLEDs). So synthesis of 2,3-fused polycyclic indole derivatives is very valuable because of its pharmacological activity of antiproliferation and other biological activities.Organic iodonium salts have also been widely applied and became one of the most active research fields in modern organic synthesis chemistry because of their characteristics of high selectivity, environmental friendly feature, mild reaction condition and easy preparation. In particularly, the diaryliodonium salts can afford powerful arenium ion or aryl radical under catalyst to react with a wide range of nucleophiles to synthsize valuable aromatic compounds, Therefore, the modern organic synthesis has been widely used in a wide range of applications. Isothiocyanate is a kind of important organic synthetic intermediate. It is widely used in medicine and pesticide synthesis, particularly used in the synthesis of some heterocyclic compounds with biological activities.Based on our group’s previous work about the research of isothiocyanates and diaryliodonium salts, A novel strategy for 23 kinds of thiochromeno[2,3-b]indoles with 2-isothiocyanato-1-(2-phenyl-1-ethynyl)benzene and diaryliodonium salts with Cu(OTf)2 as catalyst was set up. Mechanism was demonstrated in detail on the basis of our control experiments and crystallographic data. The structures of all the target compounds were confirmed by 1H NMR, 13 C NMR and HRMS.