Study On The Synthesis Of 6-Arylthio Phenanthridines And 1-Arylthio Isoquinolines By Using Isothiocyanates And Diaryliodonium Salts

The phenanthridine nucleus is a privileged scaffold usually found in bioactive natural products. Many synthetic phenanthridine-containing molecules show antitumor and antibacterial activities. In addition, phenanthridine derivatives reveal significant optoelectronic properties. As to isoquinolines, they constitute an important class of alkaloids. Isoquinolines, dihydroisoquinolines and tetrahydro-isoquinolines possess a vast spectrum of biological and pharmaceutical activities including antibacterial, antitumor, antitubercular and anti-HIV. They also have been used as intermediates in organic synthesis. We all know that, organosulfur compounds are also very important as pharmaceutical agents. Therefore, the study on the synthesis of 6-arylthio phenanthridines and 1-arylthio isoquinolines is very valuable.Isothiocyanates are a kind of important organic synthetic intermediates. They are widely used in medicine and pesticide synthesis, particularly used in the synthesis of some heterocyclic compounds with biological activities. Organic hypervalent iodonium salts have also been widely applied and became one of the most active research field 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 various aromatic compounds.Based on our group's previous work about the research of isothiocyanates and diaryliodonium salts, a new method for synthesis of 6-arylthiophenanthridines was developed with 2-isothiocyanato-1,1'-biphenyl and diaryliodonium salts as substrates, CuCl (0.1 equiv) as catalyst and 25 novel thiophenanthridines were synthesized. The plausible reaction mechanism was studyed in detail through control experiments which demonstrated it involved in arenium ion. Besides, on the basis of our established reaction, the natural product Trisphaeridine was synthesized.In the meantime, we also established a new method for synthesis of 1-arylthio-3,4-dihydroisoquinolines. Eventually,5 new 1-arylthio-3,4-dihydroiso-quinolines were synthesized with (2-isothiocyanato-ethyl)benzene and diaryliodonium salts as substrate in the presence of CuCl (0.1 equiv), and its structure was determined by single crystal diffraction analysis.The structures of all the synthetic compounds were confirmed by 1H NMR,13C NMR and HRMS.