Direct functionalization of labile alkoxyamines

One-Step Synthesis of Azlactone-Functionalized SG1-Based Alkoxyamine for Nitroxide-Mediated Polymerization and Bioconjugation

“…For instance, the BlocBuilder alkoxyamine based on the SG1 nitroxide (Figure a), which is one of the most potent alkoxyamines developed so far, ,− possesses a carboxylic acid moiety that enables only low degrees of coupling with various alcohols using carbodiimide-based catalysis . The low yields observed are likely due to both the crowded structure of the carboxylic acid moiety and the higher lability of the alkoxyamine once the carboxylic acid group is activated. , Low to moderate coupling efficiencies were also reported using preactivated alcohols, highlighting the difficulty to prepare ester derivatives of the BlocBuilder alkoxyamine . To confer higher coupling abilities, the BlocBuilder alkoxyamine can be converted into its N -succinimidyl (NHS) ester derivative (Figure b), which is susceptible to reaction with bulkier amine-containing substrates such as peptides/proteins or silica particles. , Further derivatizations of the NHS alkoxyamine lead to a variety of different amine-containing linkers bearing functional groups, such as alkene for thiol–ene coupling, hydroxyl for initiating the ring-opening polymerization of lactide, or (3-aminopropyl)­triethoxysilane for the surface grafting of silica particles.…”

“…20 The low yields observed are likely due to both the crowded structure of the carboxylic acid moiety and the higher lability of the alkoxyamine once the carboxylic acid group is activated. 20,21 Low to moderate coupling efficiencies were also reported using preactivated alcohols, highlighting the difficulty to prepare ester derivatives of the BlocBuilder alkoxyamine. 21 To confer higher coupling abilities, the BlocBuilder alkoxyamine can be converted into its N-succinimidyl (NHS) ester derivative (Figure 1b), 22 which is susceptible to reaction with bulkier amine-containing substrates such as peptides/proteins 23 or silica particles.…”

“…20,21 Low to moderate coupling efficiencies were also reported using preactivated alcohols, highlighting the difficulty to prepare ester derivatives of the BlocBuilder alkoxyamine. 21 To confer higher coupling abilities, the BlocBuilder alkoxyamine can be converted into its N-succinimidyl (NHS) ester derivative (Figure 1b), 22 which is susceptible to reaction with bulkier amine-containing substrates such as peptides/proteins 23 or silica particles. 24,25 Further derivatizations of the NHS alkoxyamine lead to a variety of different amine-containing linkers bearing functional groups, such as alkene for thiol−ene coupling, 26 hydroxyl for initiating the ring-opening polymerization of lactide, 22 or (3-aminopropyl)triethoxysilane 20 for the surface grafting of silica particles.…”

Intramolecular Hydrogen Bond in Alkoxyamines. Influence on the C–ON Bond Homolysis

“…Interested in the consequences of the existence of an IHB between the alkyl and the nitroxyl fragments of an alkoxyamine and following our ongoing program of synthesis and characterization of new functionalizable or chemically–activatable alkoxyamines, − we propose herein a new alkoxyamine 2a , carrying an alcohol function on the alkyl fragment that presents an IHB strikingly influencing the C–ON bond homolysis as well as several derivatives 2b – f (Figure )…”

Dual-initiator alkoxyamines with an N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide moiety for preparation of block co-polymers

“…21 As far as we know, there is only one report on the esterication of 1 using the carboxylate function. 22 A few years ago, 23,24 we developed external triggering of C-ON homolysis with alkoxyamine 2 ( Fig. 1) and demonstrated its potential for NMP.…”