Solid-Phase Organic Synthesis Based On Polymer-Supported Organoselenium Reagents

In this dissertation, the preparation of polystyrene-supported organoselenium reagents and their applications in solid-phase organic synthesis reaction were investigated.Firstly, 1% cross-linked polystyrene-supported methylα-selenopropionate, 2-selenopropiophenone, 1-selenoethyl phenyl sulfone and diethyl 1-selenoethylphosphonate were prepared from polystyrene-supported lithium selenide with methyl 2-bromopropionate, 2-bromopropiophenone, 1-bromoethylphenyl sulfone and diethyl 1-bromoethylphosphonate, respectively. Treatment of lithio derivatives of these polystyrene-supported selenium reagents with aldehydes respectively, followed by selenoxide syn—elimination cleavage of selenium resins with 30% hydrogen peroxide afforded Baylis-Hillman products in good yields and high purities. The residual resin-polystyrene-supported phenylseleninic acid can be converted to polystyrene-supported selenenyl bromide for recycle after simple treatment. Evident advantages of this method are mild reaction conditions, easy operation, odorlessness, good yields, and high purity of products.Secondly, Treatment of 1% cross-linked polystyrene-supportedβ-bromoethyl selenide easily prepared from polystyrene-bound selenenyl bromide with tert-BuOK in THF at room temperature afforded the vinyl selenide resin, which was treated nitrile oxides generated in situ from oximes and N-chlorosuccinimide (NCS) to form the isoxazoline selenide intermediate. Then the isoxazoline resins were cleaved by selenoxide syn-elimination with 30% hydrogen peroxide, or by nuclophilic iodine substituted with sodium iodide and methyl iodide to afford 3-substituted isoxazoles and 3-substituted 5-iodoisoxazolines in with good yields and high purities, respectively. The residual resin-polystyrene-supported methyl selenide can be regenerated and used by treatment with bromide.Finally, 2-substituted 3-bromobenzo[b]furans and 3-iodobenzo[b]furans derivatives were synthesized through 1% cross-linked polystyrene-bound selenium-induced intramolecular electrophilic cyclization of 2-(arylethynyl)anisole compounds, followed by bromide or substitution cleavage of selenium resins with bromide or sodium iodide and methyl iodide in with good yields and high purities, respectively. And also the polystyrene-bound selenium bromide can be regenerated and reused.