49755-94-4Relevant articles and documents
Enhanced Spin-capturing polymerization and radical coupling mediated by cyclic nitrones
Ranieri, Kayte,Conradi, Matthias,Chavant, Pierre-Yves,Blandin, Veronique,Barner-Kowollik, Christopher,Junkers, Thomas
, p. 1110 - 1116 (2012)
A series of cyclic nitrones have been tested for their spin-trapping activity in the enhanced spin-capturing polymerization of styrene and in nitrone-mediated radical coupling reactions. rac-2-Isopropyl-2,3-dimethyl-1-oxy- 2,3-dihydro-imidazol-4-one was found to be the most efficient nitrone. The specific polystyrene macroradical addition rate to this nitrone was determined to be 8.0103Lmol-1s-1, which is by a factor of 10 higher than for previously studied compounds. Via enhanced spin-capturing polymerization, polymers in the range of oligomers to 30000gmol-1 were obtained. A strong dependence of molecular weight on monomer conversion was observed, which can be explained by the high trapping rate. In nitrone-mediated radical coupling, almost ideal coupling of bromine-functional polymers was obtained and the successful introduction of the residual alkoxyamine functionality confirmed.
Inexpensive, multigram-scale preparation of an enantiopure cyclic nitrone via resolution at the hydroxylamine stage
Thiverny, Maryse,Demory, Emilien,Baptiste, Benoit,Philouze, Christian,Chavant, Pierre Y.,Blandin, Veronique
experimental part, p. 1266 - 1273 (2011/11/30)
The reduction of the chiral, racemic nitrone MiPNO provides a secondary hydroxylamine. Its O-acylation with O,O'-dibenzoyl-l-tartaric acid anhydride gives two diastereomers, that can be easily separated by selective dissolution in orthogonal solvents. The recovery of the enantiopure nitrone is then carried out in a single step. The process allows the straightforward isolation of (R) and (S)-MiPNO in 57% and 38% yield, respectively, from rac-MiPNO.
Effects of covalent modifications on the solid-state folding and packing of N-malonylglycine derivatives
Dado, Gregory P.,Desper, John M.,Holmgren, Steven K.,Rito, Christopher J.,Gellman, Samuel H.
, p. 4834 - 4843 (2007/10/02)
The syntheses and crystal structures of triamides 1-4 and diamide esters 5 and 6 are described. In crystalline form, 1, 2, and 4 adopt conformations containing an intramolecular N-H?C=T hydrogen bond in a nine-membered ring. Triamide 3 and ester diamides 5 and 6 experience only intermolecular hydrogen bonding in the solid state. We have previously concluded, on the basis of IR and 1H NMR measurements, that triamide 1 manifests several different internal hydrogen-bonding patterns in methylene chloride solution. The conformation adopted by 1 in the solid state is similar to the folding pattern that we earlier deduced to be most enthalpically favorable in nonpolar solution, although an intermolecular hydrogen bond detected in the crystalline 1 does not occur at the dilutions used for the solution experiments. The intramolecularly hydrogen-bonded solid-state conformations of 2 and 4 are similar to those that predominate in methylene chloride solution. In contrast, the extended, intermolecularly hydrogen-bonded conformation of 3 in the solid state differs from the intramolecularly hydrogen-bonded form that is favored in dilute methylene chloride. The solid-state conformations of diamide esters 5 and 6 also differ from the forms that appear to be most highly populated in nonpolar solution. The crystal packing of 2-4 is discussed in detail. Although the juxtapositions of neighbors vary among these triamides, in all three cases a pattern of alternating sheets of polar and nonpolar fragments is observed.
