Liquid-Phase Organic Synthesis Using Poly (Etheylene Glycol) As Support

Recently, the liquid-phase organic synthesis supported by soluble polymer was applied successfully to combinatorial chemistry and parallel synthesis. Synthetic approaches which utilize soluble polymers termed liquid-phase chemistry, couple the advantages of homogeneous solution chemistry with those of solid phase methods. Under the previous research work of our workgroup, PEG-supported piperazine was synthesized as a Knoevenagel catalyst; a series of multisubstituted acrylic acid methyl esters and isoxazolines have been synthesized in this paper. All reactions were highly efficient in giving the desired compounds in high yields by simple precipitation and wash, which suited the demand of parallel and combinatorial of small molecule libraries.Firstly, Polymer-supported piperazine, that is PEG-supported piperazine, as a Knoevenagel catalyst has been prepared and evaluated. The performance of reusing the catalyst has been studied. The result indicate that it can effectively catalyze Knoevenagel condensation and can be reused at least two times. Secondly, the polymer-supported active methylene compound perform the Knoevenagel condensation with aromatic aldehydes to give eight 2-Acetyl-3-phenylacrylic acid methyl esters. The yields were in the range of (85～98%).Thirdly, we have developed a practice and efficient liquid-phase synthetic method of 3,5-isoxazoline via 1,3-dipolar cycloaddition. PEG-supported alkene reacted with in situ generated nitrile oxides to give Eleven bisubstituted-isoxazolines. The yields were in the range of (49-91%).