New Click Chemistry: Polymerization Based on 1,3-Dipolar Cycloaddition of a Homo Ditopic Nitrile N-Oxide and Transformation of the Resulting Polymers into Reactive Polymers

Abstract

Applicability and productivity of new click chemistry that exploits a nitrile N-oxide as a 1,3-dipole in polymer synthesis were demonstrated by the polymerization of diynes with a homo ditopic aromatic nitrile N-oxide. The nitrile N-oxide was synthesized in situ by the reaction of the corresponding hydroxamoyl chloride with molecular sieves 4 Å. The click polymerization of various ditopic diynes and the nitrile N-oxide efficiently produced polyisoxazoles in high yields. The homo ditopic nitrile N-oxide was also useful for the connection of bisacetylene-terminated polymers to give multiblock copolymers in very high yield. The resulting polyisoxazoles agree well with the structural assignment obtained by the 1H and 13C NMR analyses. The generated polyisoxazoles showed improved thermal stability due to the presence of isoxazole moieties. The molecular diversity of the obtained polyisoxazoles was confirmed by the selective transformations of the isoxazole moieties into β-aminoenone or β-aminoalcohol moieties with high conversion rates. The thermal decomposition temperature of the transformed polymers was lower than that of the polyisoxazoles because of the formations of abundant amino and hydroxyl groups. Furthermore, the functionality of poly(β-aminoalcohol) was proven by quantitatively cross-linking the polymers by treatment with terephthalaldehyde or methylene diphenyl diisocyanate.

1,3‐Alternate Calix[4]arene as a Homobinuclear Ditopic Fluorescent Chemosensor for Ag+ Ions

“…[8b] Subsequent N À O bond cleavage of the isoxazole moiety of 4 by Fe powder and NH 4 Cl led to corresponding enaminones substituted calix [4]arene L in 60 % yield. [14] After ring opening reaction of 4, the proton H b at 6.02 ppm on the isoxazole ring of 4 was upfield shifted to 5.67 ppm, which was assigned to be the aunsaturated proton H b of L (see the Supporting Information, Figure S7). In addition, the amino protons were found as two broad signals at 5.51 and 10.31 ppm, in which the most downfield shifted signal was due to the strong intramolecular hydrogen bonding between the amino proton and carbonyl oxygen.…”

Stereoregular poly(methyl methacrylate) with double-clickable ω-end: synthesis and click reaction

“…[3][4][5] From the viewpoint of polymer synthesis, to say nothing of the polyaddition via click chemistry, [6][7][8][9][10][11] polymers possessing clickable pendant groups 12,13 and/or end-functionalities [14][15][16] have attracted researchers' attention, as such polymers can be used as 'building blocks' for syntheses of highly functionalized polymers, 17,18 construction of sophisticated topology, 19,20 and surface modification 21,22 .…”

Fluorescent poly(boron enaminoketonate)s: synthesis via the direct modification of polyisoxazoles obtained from the click polymerization of a homoditopic nitrile N-oxide and diynes

“…One regioisomer was preferentially formed as confirmed by the 1 H NMR spectra. 16,17,37 Table 2 summarizes the thermal properties of the resulting polymers. All polyisoxazoles and PBEKs, except for poly-3, are crystalline polymers, as suggested by the observed melting temperatures.…”