Synthesis of Branched Monodisperse Oligoethylene Glycols and ¹⁹F MRI-Traceable Biomaterials through Reductive Dimerization of Azides

Abstract

Multifunctionalized and branched M-OEGs represent valuable PEGylation agents, linkers, and scaffolds in biomedicine. However, the tedious synthesis limited their availability and application. We herein present an azide reductive dimerization method for the convenient synthesis of aza-M-OEGs and derivatives, which provides easy access to a variety of multifunctionalized and branched M-OEGs in one step. With this method, hexa-arm M-OEGs with 54 symmetrical fluorines were synthesized in two steps as a water-soluble, self-assemble, 19F MRI sensitive, and biocompatible dendritic biomaterial.

Retraction: Versatile Molecule for Single‐Laser‐Triggered Redox‐Responsive Enhanced Dual‐Modal Imaging and Synergistic Photothermal‐Photodynamic Therapy

“…After treating M-PEG 8 with methylbenzenesulfonyl chloride and sodium hydroxide, the tosylate intermediate was directly reacted with sodium azide in N,Ndimethylformaldehyde to give azide 9, which was reductively dimerized into M-PEG secondary amine 10 using a method developed in this group. [17] Amine 10 was prepared on multi-gram scales in a 48% yield over two steps. Second, 12-perfluoro-tertbutoxyl-1-dodecanol 14 was prepared by first transforming one of the hydroxyl groups in 1,12-dodecanediol 11 into bromine with hydrogen bromide and then nucleophilic substituted with sodium perfluoro-tert-butoxide in a 66% yield over two steps, which then transformed into azide 15 and then reductively dimerized into hydrofluorocarbon secondary amine 16 with a 50% yield over two steps.…”

Fluorinated hydrogel nanoparticles with regulable fluorine contents andT2relaxation times as19F MRI contrast agents

“…11,12 Different from 1 H MRI CAs that inuence the relaxation properties of nearby water protons, the uorine atoms in 19 F MRI CAs are able to be visualized directly by MRI equipment. 13 In addition, 19 F has a 100% natural abundance and a gyromagnetic ratio close to hydrogen (83% compared with hydrogen), giving 19 F MRI excellent imaging resolution. 14 Another advantage of 19 F MRI is the images have a higher imaging contrast due to the absence of 19 F atoms in the detecting domains.…”

Synthesis of symmetrical secondary oligoethylene glycolated amines from diethanolamine

“…Recently, an azide reductive dimerization strategy for the synthesis of M-OEG secondary amines was developed by this group (Scheme 1), 7 which were obtained in one step from M-OEGs monoazides. However, sodium azide is explosive and requires stringent safety regulations, posing a significant safety issue, especially on large scales.…”

“…In contrast, the β-naphthylmethyl group is highly stable under acidic and basic conditions. Furthermore, because careful chromatographic purification is always necessary during M-PEGs synthesis, 7–9 strong UV absorption of the β-naphthylmethyl group would dramatically simplify the reaction monitoring and product purification.…”