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Applications Of Polymer-Supported Organselenium Reagents In Solid-Phase Organic Synthesis Reations

Posted on:2009-06-10Degree:MasterType:Thesis
Country:ChinaCandidate:L GuoFull Text:PDF
GTID:2121360272480855Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
In this dissertation, the preparation of polymer-bound organic selenium reagents and their applications in solid-phase organic synthesis (SPOS) was first introduced and then the SPOS based on polymer-bound organic selenium reagents was further investigated.Firstly, reaction of cross-linked (1%) polystyrene bound selenium bromide with LiBH4 afforded the corresponding polystyrene-supported lithium selenide, which was treated withα-bromopropionic acid to form polymer-boundα-selenopropionic acid. Acylation of this selenium reagent with acid hydrazides, followed by cyclocondensation with arylphosphazoanilides, and oxidation-elimination with 30 % hydrogen peroxide efficiently afforded vinyl-substituted 1,2,4-triazoles in yields (74-83 %) and purities (88-94 %).Secondly, treatment of the cross-linked (1%) polystyrene-supported lithium selenide prepared as above with epoxides gave polymer-bound 2-hydroxyalkyl phenyl selenides, which were reacted with primary or secondary organic halides and subsequent oxidation-elimination with 30 % hydrogen peroxide to yield vinyl alkyl ethers in yields (74-90 %) and purities (85-94 %).Finally, reaction of Wang resin withα-phenylselenopropanoic acid in DMF in the presence of DIC/DMAP/NMM readily gave rise to Wang resin boundα-phenylselenopropionate ester, which was reacted with LDA, followed successively by treatment with aldehyde and 30 % hydrogen peroxide afforded Wang resin bound Baylis-Hillman product intermesiate, and subsequent cleavage from the PEG using 0.1 N MeONa in MeOH/THF (1:4, V/V) or sodium hydroxide aqueous solution afford Baylis-Hillman product yields (83-93 %) and purities (90-96 %).The evident advantages of the present methods for preparation of the above three classes compounds are mild reaction conditions, easy operation, odorlessness, good yields, and high purities (by HPLC analysis) of crude products without further isolation and purification.
Keywords/Search Tags:Solid-phase organic synthesis, Organic selenium reagent, Cross-linked (1%) polystyrene, Wang resin, vinyl-substituted 1,2,4-triazole, Vinyl alkyl ether, Baylis-Hillman product, 30 % Hydrogen peroxide, Oxidation-elimination
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