Iodine-promoted Direct Thiolation Of Maleimides Using Dimethyl Sulfoxide And Thiols As Thiolation Reagents

Maleimides and indoylmaleimides have good antitumor and antibacterial activity.Due to their good conjugated structure,these compunds show good fluorescence property.They have been widely used in pharmaceutical and photoelectric material areas.Among them,3-thiolmaleimides have been drawn extensive attention beacause of their good antibacterial activity.Therefore,it is important to develop a direct and practical procedure for the synthesis of3-thiomaleimides.I₂-promoted thiolation reactions of malaimides or indolylmaleimides with DMSO and thiols were mainly studied.The reaction conditions were optimized.A series of 3-methylthiolmaleimides,3-phenylthiolmaleimides and 3-indolyl-4-phenylthiolmaleimides were synthesized in proper conditions.The reaction conditions were simple,and the reaction time was short.What’s more,the materials were easily available.It is a simple and efficient way for the formation of C-S bond.The main contents of this thesis are as follows:1.A practical I₂-promoted methylthiolation reactions of maleimides have been developed to synthesize 3-methylthiolmaleimides with DMSO.Then,several parameters were altered in an attempt to improve the yield of desired product.Finally,six 3-methylthiolmaleimides were synthesized with yields of 75%⁹2%.2.In order to explore the methylthiolation reaction scope,3-indolylmaleimides were prepared from maleimides and indoles.Firstly,3-indolylsuccinimides were obtained from indoles and maleimides in the presence of BF₃?OEt₂ as catalyst.Then,3-indolylsuccinimides were oxidated to3-indolylmaleimides in the presence of K₂S₂O₈ as oxidant.Finally,four 3-indolylmaleimides were obtained with yields of 72%⁸2%.When 3-indolylmaleimides were used as substrates,3-methylthiolmaleimide was not formed.3-Iodo-4-indolylmaleimide was generated with 75%yield.Finally,the reaction mechanism was discussed.3.An efficient I₂-promoted thiolation reactions of maleimides or indolylmaleimides with thiols have been developed to synthesize 3-thiolmalemides.Then,the reaction conditions were optimized to improve the yield of desired product.Finally,eight 3-thiolmaleimides and3-indolyl-4-phenylthiomaleimides were obtained with yields of 38%⁷8%.However,3-thiolsuccinimide was formed via Michael addition without I₂.Finally,the reaction mechanism was suggested.In conclusion,twenty compounds were synthesized including six 3-methylthiolmaleimides,eight 3-thiolmaleimides and 3-indoyl-4-thiolmaleimides,four 3-indoylmaleimides and so on.Among them,twelve compunds have not been reported.Their structures were characterized with IR,¹HNMR,¹³CNMR and HRMS analysis.