35739-01-6Relevant academic research and scientific papers
Molecularly imprinted polymeric adsorbents for byproduct removal
Ye, Lei,Ramstroem, Olof,Mosbach, Klaus
, p. 2789 - 2795 (2007/10/03)
In this study, both diastereo- and enantioselective adsorbents for a dipeptide derivative were prepared using a molecular imprinting technique. The diastereo- and enantioisomers for the dipeptide derivative N-(benzyloxycarbonyl)aspartylphenylalanine methyl ester (ZAPM), in addition to the α- and β-isomers, were chosen as test compounds for the investigation of the imprinting effect. The close similarities between the structures of different isomers make it possible to interpret the roles of template structure on specific molecular recognition. A highly specific byproduct scavenger was prepared by simultaneously incorporating methacrylic acid and vinylpyridine as functional monomers. The binding selectivities of polymeric adsorbents for the α- and β-isomers are shown to be greatly enhanced by introducing enantiocomplementarities into the polymer matrixes. An anti-β-L,L-ZAPM polymer was applied in a solid-phase extraction protocol, for the purification of the product in the chemical synthesis of N-protected aspartame. Finally, polymer beads were also imprinted against β-L,L-ZAPM using suspension polymerization performed in perfluorocarbon fluid. The imprinted polymer beads displayed the same binding characteristics as the imprinted bulk polymer and can be envisaged for the use of product purification in chromatographic mode.
Effects of Solvents and Additives on the Reaction of N-Benzyloxycarbonyl-L-Aspartic Anhydride with L-Phenylalanine Methyl Ester ( Synthesis of Aspartame)
Yang, Chin-Ping,Su, Chein-Shyong
, p. 5186 - 5191 (2007/10/02)
N-Benzyloxycarbonyl-L-aspartic anhydride (Z-L-aspartic anhydride) was reacted with L-phenylalanine methyl ester.The nature of the ring-opening reaction was effected by the organic solvent.In Me2SO, DMF, and dimethylacetamide the β-isomer of Z-L-aspartyl-L-phenylalanine methyl ester (ZAPM) was predominant while in glacial acetic acid, esters, ketones, ethers, chlorohydrocarbons, acetonitrile, toluene, etc. the α-isomer of ZAPM prevailed.Especially in glacial acetic acid, the yield of α-form ZAPM reached more than 85percent.The results of reactions in mixed solvents like acetonitrile-Me2SO and ethyl acetate-acetonitrile showed that the yield of α-ZAPM changed linearly with a change in the composition of the mixed two solvents.The reaction in acetonitrile-acetic acid and Me2SO-acetic acid showed that the addition of acetic acid not only caused a solvent effect by itself, but that the acid also affected the reaction.Therefore, the yield of α-ZAPM was increased by use of a mixed solvent containing only a small amount of glacial acetic acid.A mechanism to explain these experimental phenomena is presented.
