This highlight describes recent developments in reversible addition-fragmentation transfer (RAFT) polymerization. Succinct coverage of the RAFT mechanism is supplemented by details of synthetic methodologies for making a wide range of architectures ranging from stars to combs, microgels, and blocks. In addition, RAFT reactions in different media such as emulsion and ionic liquids receive attention. Finally, a specific example of a novel material design is briefly introduced, whereas polymers prepared via RAFT are adopted for microporous/honeycomb membrane design.

RAFTing down under: Tales of missing radicals, fancy architectures, and mysterious holes

The combination of reversible chain transfer chemistry with highly orthogonal [2 + 3] cycloadditions ('click chemistry') allows for the synthesis of well-defined block copolymers of monomers with extremely disparate reactivities. © The Royal Society of Chemistry.

RAFT and click chemistry: A versatile approach to well-defined block copolymers

Ynamides are special alkynes bearing an electron-withdrawing group on the nitrogen atom, and they have been extensively studied over the past decade. However, the addition of functional groups acro...

Reversal of Regioselectivity in Ynamide Chemistry

An I2-mediated metal-free oxidative C–N bond formation methodology has been established for the regioselective pyrazole synthesis. This practical and eco-friendly one-pot protocol requires no isolation of the less stable intermediates hydrazones and provides a facile access to a variety of di-, tri-, and tetrasubstituted (aryl, alkyl, and/or vinyl) pyrazoles from readily available α,β-unsaturated aldehydes/ketones and hydrazine salts.

I2-Mediated Oxidative C–N Bond Formation for Metal-Free One-Pot Synthesis of Di-, Tri-, and Tetrasubstituted Pyrazoles from α,β-Unsaturated Aldehydes/Ketones and Hydrazines

Over the past two decades, the development and application of ynamide chemistry have received more and more attention. Ynamides have proven to be versatile reagents for organic synthesis, and have been widely applied to the rapid assembly of a diverse range of structurally complex N-containing molecules, especially the valuable N-heterocycles. In comparison with the well-established transition metal-catalyzed reactions of ynamides, metal-free ynamide transformations have relatively seldom been exploited. Recently, Bronsted acid-mediated reactions of ynamides represent significant advances in ynamide chemistry. This review summarizes the latest trends and developments of Bronsted acid-mediated reactions of ynamides, including cycloaddition, cyclization, intramolecular alkoxylation-initiated rearrangement, oxygen atom transfer reactions and hydro-heteroatom addition reactions.

Brønsted acid-mediated reactions of ynamides.

A practical and transition-metal-free oxidative cyclization of acylhydrazones into 1,3,4-oxadiazoles has been developed by employing stoichiometric molecular iodine in the presence of potassium carbonate. The conditions of this cyclization reaction also work well with crude acylhydrazone substrates obtained from the condensation of aldehydes and hydrazides. A series of symmetrical and asymmetrical 2,5-disubstituted (aryl, alkyl, and/or vinyl) 1,3,4-oxadiazoles can be conveniently generated in an efficient and scalable fashion.

I2-Mediated Oxidative C–O Bond Formation for the Synthesis of 1,3,4-Oxadiazoles from Aldehydes and Hydrazides

2-Amino-substituted 1,3,4-oxadiazoles and 1,3,4-thiadiazoles were synthesized via condensation of semicarbazide/thiosemicarbazide and the corresponding aldehydes followed by I2-mediated oxidative C–O/C–S bond formation. This transition-metal-free sequential synthesis process is compatible with aromatic, aliphatic, and cinnamic aldehydes, providing facile access to a variety of diazole derivatives bearing a 2-amino substituent in an efficient and scalable fashion.

Synthesis of 2-amino-1,3,4-oxadiazoles and 2-amino-1,3,4-thiadiazoles via sequential condensation and I2-mediated oxidative C–O/C–S bond formation.

Regioselective synthesis of 3,4-disubstituted isocoumarins through the Pd-catalyzed annulation of 2-iodoaromatic acids with ynamides

Self-assembly of amphiphilic polymers in aqueous solution builds up versatile carrier platforms for therapeutic delivery. Amphiphilic polymers specifically provide “hydrophobic pockets” for the enc...

Hongxu Liu

Papers

I2-Mediated Oxidative C–O Bond Formation for the Synthesis of 1,3,4-Oxadiazoles from Aldehydes and Hydrazides

Synthesis of 2-amino-1,3,4-oxadiazoles and 2-amino-1,3,4-thiadiazoles via sequential condensation and I2-mediated oxidative C–O/C–S bond formation.

Regioselective synthesis of 3,4-disubstituted isocoumarins through the Pd-catalyzed annulation of 2-iodoaromatic acids with ynamides

Blended Assemblies of Amphiphilic Random and Block Copolymers for Tunable Encapsulation and Release of Hydrophobic Guest Molecules

Synthesis of 3-Substituted 2-Aminochromones via Sn(IV)-Promoted Annulation of Ynamides with 2-Methoxyaroyl Chlorides