A Study On Synthesis Of Substituted4,5-Dihydrofurans Promoted By Ki And H₂O₂

Dihydrofurans as well as their derivatives are not only key structural unit in manynatural compounds, but also important synthetic precursors in organic synthesis. Therefore,it is highly meaningful to exploring simple and efficient synthetic methodologies toconstruct this type of compounds. In this thesis, the synthesis methodology ofdihydrofurans in recent ten years was reviewed. Then, the oxidative coupling reactionespecially promoted by hypervalent-iodine was reviewed.In this thesis, a environmental friendly, atom economical, efficiently syntheticmethodology of constructing multisubsitued4,5-dihydrofurans was developed. The mainwork was as follows:(1) Synthesis of1-nitroalkene-4-ol as substrate starting from the simply availablematerials of1,3-dicarbonyl and nitroalkene.(2) Using3a as mode substrate to synthesis4,5-dihydrofurans via oxidative couplingbetween enol and the α position of nitryl group promoted by KI and H2O2.Then thereaction parameters was optimized by changing of catalysts, solvents, the amount ofoxidants, the reaction time and temperature etc.(3) The scope of substrates was explored that3a-3j gave good yeilds(31%-81%) as wellas excellent diastereoselectivity, the d.r. values are up to20:1.(4) The tentative mechanism of this reaction was investigated.