Simple and Efficient Synthesis of Various Alkoxyamines for Stable Free Radical Polymerization

Matyjaszewski, Krzysztof; Woodworth, Brian E.; Zhang, Xuan; Gaynor, Scott G.; Metzner, Zack

doi:10.1021/ma9807264

Cited by 260 publications

(250 citation statements)

References 23 publications

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“…1:1, see the Supporting Information)) using a Cu I -mediated process. [27] cis peptide bond can be strongly enhanced by the introduction of a pseudoproline residue, depending on its C(2) substituents. In particular, the 2,2-dimethylated thiazolidine derivative can induce up to 100 % cis conformation in the preceding peptide bond in model di-and tripeptides.…”

mentioning

confidence: 99%

Pseudoprolines: Targeting acis Conformation in a Mimetic of the gp120 V3 Loop of HIV-1

Wittelsberger

Keller

Scarpellino

et al. 2000

Angew. Chem. Int. Ed.

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The specific recognition of cis peptide bonds is possible with antibodies that are directed against cyclic and linear peptide antigens derived from the V3 loop of the HIV‐1 protein gp120, into which a thiazolidine derivative (pseudoproline) has been introduced (see schematic representation). This extension of the pseudoproline concept may help to decipher the unique role of proline residues in biologically relevant systems.

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mentioning

confidence: 99%

Pseudoprolines: Targeting acis Conformation in a Mimetic of the gp120 V3 Loop of HIV-1

Wittelsberger

Keller

Scarpellino

et al. 2000

Angew. Chem. Int. Ed.

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“…The more reliable M n of PCL measured by GPC can be calculated by a correction formula The one-pot procedure was carried out in presence of CuBr/Cu/PMDETA at 70 C for 24 h, the click chemistry between azide group and alkyne functional group, and ATNRC reaction between TEMPO group and bromine group were realized simultaneously. 24 The GPC traces of star terpolymers composed of PS, PtBA, and PEO or PCL arms were shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

One‐pot preparation of 3‐miktoarm star terpolymers via “click chemistry” and atom transfer nitroxide radical coupling reaction

Wang

Lin

et al. 2008

J. Polym. Sci. A Polym. Chem.

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“…[49][50][51][52][53][54] Alkoxyamines (with the exception of 1c and 1e) were prepared according to the method of Schoening et al, [55,56] whereby alkyl radicals are generated in situ from a ketone or aldehyde, copper (I) chloride, and hydrogen peroxide. In the presence of the nitroxide, nascent radicals are readily trapped, forming the desired alkoxyamines, listed in Scheme 2.…”

Section: Synthesismentioning

confidence: 99%

Experimental evidence for competitive N O and O C bond homolysis in gas-phase alkoxyamines

Marshall

Gryn’ova

Coote

et al. 2015

International Journal of Mass Spectrometry

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The extensive use of alkoxyamines in controlled radical polymerisation and polymer stabilisation is based on rapid cycling between the alkoxyamine (R1R2NO-R3) and a stable nitroxyl radical (R1R2NO•) via homolysis of the labile O-C bond. Competing homolysis of the alkoxyamine N-O bond has been predicted to occur for some substituents leading to production of aminyl and alkoxyl radicals. This intrinsic competition between the O-C and N-O bond homolysis processes has to this point been difficult to probe experimentally. Herein we examine the effect of local molecular structure on the competition between N-O and O-C bond cleavage in the gas phase by variable energy tandem mass spectrometry in a triple quadrupole mass spectrometer. A suite of cyclic alkoxyamines with remote carboxylic acid moieties (HOOC-R1R2NO-R3) were synthesised and subjected to negative ion electrospray ionisation to yield [M − H]− anions where the charge is remote from the alkoxyamine moiety. Collision-induced dissociation of these anions yield product ions resulting, almost exclusively, from homolysis of O-C and/or N-O bonds. The relative efficacy of N-O and O-C bond homolysis was examined for alkoxyamines incorporating different R3 substituents by varying the potential difference applied to the collision cell, and comparing dissociation thresholds of each product ion channel. For most R3 substituents, product ions from homolysis of the O-C bond are observed and product ions resulting from cleavage of the N-O bond are minor or absent. A limited number of examples were encountered however, where N-O homolysis is a competitive dissociation pathway because the O-C bond is stabilised by adjacent heteroatom(s) (e.g. R3 = CH2F). The dissociation threshold energies were compared for different alkoxyamine substituents (R3) and the relative ordering of these experimentally determined energies is shown to correlate with the bond dissociation free energies, calculated by ab initio methods. Understanding the structure-dependent relationship between these rival processes will assist in the design and selection of alkoxyamine motifs that selectively promote the desirable O-C homolysis pathway. homolysis is a competitive dissociation pathway because the O-C bond is stabilised by adjacent heteroatom(s) (e.g., R 3 = CH 2 F). The dissociation threshold energies were compared for different alkoxyamine substituents (R 3 ) and the relative ordering of these experimentally determined energies is shown to correlate with the bond dissociation free energies, calculated by ab initio methods.Understanding the structure-dependent relationship between these rival processes will assist in the design and selection of alkoxyamine motifs that selectively promote the desirable O-C homolysis pathway.

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Simple and Efficient Synthesis of Various Alkoxyamines for Stable Free Radical Polymerization

Cited by 260 publications

References 23 publications

Pseudoprolines: Targeting acis Conformation in a Mimetic of the gp120 V3 Loop of HIV-1

Pseudoprolines: Targeting acis Conformation in a Mimetic of the gp120 V3 Loop of HIV-1

One‐pot preparation of 3‐miktoarm star terpolymers via “click chemistry” and atom transfer nitroxide radical coupling reaction

Experimental evidence for competitive N O and O C bond homolysis in gas-phase alkoxyamines

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