Synthesis of Main-Chain-Type Polyrotaxanes by New Click Polymerization Using Homoditopic Nitrile N-Oxides via Rotaxanation−Polymerization Protocol
Main-chain-type polyrotaxanes (9 and 12) and polyrotaxanes (10 and 13) were synthesized by a new click polymerization using unstable and stable homoditopic nitrile N-oxides according to rotaxanation and polymerization protocol. Rotaxane monomers were prepared from ethynyl-functionalized crown ether and sec-ammonium salt via the typical urethane end-capping protocol. The homoditopic nitrile N-oxide 8′ was generated in situ through the reaction of the corresponding hydroxamoyl chloride 8 with molecular sieves 4 Å. The click polymerization of diethynyl-functionalized rotaxane 5 and rotaxane monomer 7 with 8′ efficiently proceeded in the absence of a catalyst to afford well-defined polyrotaxanes 9 and 10 containing a polyisoxazole backbone in high yields. The polymerization of a newly developed kinetically stabilized homoditopic nitrile N-oxide 11 with rotaxane monomers yielded well-defined polyrotaxanes 12 and 13 in high yields under similar conditions. The structures of polyrotaxanes (9 and 1...
We recently generalized the formerly alignment-dependent multivariate image analysis applied to quantitative structure–activity relationships (MIA-QSAR) method through the application of the discrete Fourier transform (DFT), allowing for its application to noncongruent and structurally dive ... mehr
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