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This Account covers the recent progress made on heterocyclic mechanophores in the field of polymer mechanochemistry. In particular, the types of such mechanophores as well as the mechanisms and applications of their force-induced structural transformations are discussed and related perspectives and future challenges proposed.1 Introduction2 Types of Mechanophores3 Methods to Incorporate Heterocycle Mechanophores into Polymer Systems4 Mechanochemical Reactions of Heterocyclic Mechanophores4.1 Three-Membered-Ring Mechanophores4.2 Four-Membered-Ring Mechanophores4.3 Six-Membered-Ring Mechanophores4.4 Bicyclic Mechanophores5 Applications5.1 Cross-Linking of Polymer5.2 Degradable Polymer5.3 Mechanochromic Polymer6 Concluding Remarks and Outlook

Cycloaddition reactions of aziridines with dipolarophiles under traditional thermal or photochemical conditions entail destructive routes to form reactive intermediates such as an azomethine ylide. This article highlights a recent study that demonstrates a cycloaddition reaction of aziridine induced by mechanical force. Experimental results suggest that the force-induced cycloaddition of aziridine with dimethyl acetylenedicarboxylate as a dipolarophile does not seem to involve an ylide, with implications for a possible new reaction route.1 Rivalry between Aziridine and Epoxide2 Mechanochemically Responsive Polymers3 Aziridine Mechanophore4 Concluding Remarks and Outlook

Symmetric and asymmetric carbonates were synthesized by using alkyl or aryl 4,5-dichloro-6-oxopyridazin-1(6 H )-carboxylates. Five aryl 4,5-dichloro-6-oxopyridazin-1(6 H )-carboxylates were converted into the corresponding diaryl carbonates in good to excellent yields by treatment with potassium carbonate in refluxing THF. When the 4,5-dichloro-6-oxopyridazin-1(6 H )-carboxylates were treated with aliphatic or aromatic alcohols in the presence of potassium tert -butoxide in toluene at room temperature, they gave the corresponding symmetric or asymmetric carbonates in moderate to excellent yields. Alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6 H )-carboxylates are therefore efficient, stable, and ecofriendly alternatives to chloroformates.

Developing eco-friendly, stable, and easy-to-handle acyl sources is of great importance in synthetic and green chemistry. This study describes the synthesis of benzo[ d ]azol-2(3 H )-ones such as benzo[ d ]thiazol-2(3 H )-ones, benzo[ d ]oxazol-2(3 H )-ones, and benzo[ d ]imidazol-2(3 H )-ones using 2-phenoxycarbonyl-4,5-dichloropyridazin-3(2 H )-one in one pot. The reaction reported is carried out under neutral or acidic conditions in the presence of zinc or sodium bicarbonate to give the corresponding heterocycles in good to excellent yields. The reaction uses a solid stable carbonyl source that is a recyclable functional-group carrier, pyridazin-3(2 H )-one.

This paper describes the esterification of aromatic and aliphatic alcohols by using 2-acyl-4,5-dichloropyridazin-3(2H)-ones as an acyl source under Friedel–Crafts conditions. Twelve alcohols were reacted with four 2-acyl-4,5-dichloropyridazin-3(2H)-ones in the presence of AlCl3 in tetrahydrofuran at room temperature to give the corresponding esters in moderate to excellent yields. Thus, 2-acylpyridazin-3(2H)-ones serve as good and atom-economic acyl sources for the esterification of aromatic alcohols under Friedel–Crafts conditions, representing a rapid, practical, and efficient method of esterification.

5-Hydroxymethyl-2-furfural (HMF) was selectively converted to 2,5-diformylfuran (DFF) under mild conditions by polymer-supported IBX amide reagent, thus providing a new platform for the production of highly valuable chemicals from biomass.

A new type of magnetite/silica nanoparticle-supported N-heterocyclic carbene nickel catalyst (Mag-NHC-Ni) was developed from imidazolium with N-picolyl moieties and used as an efficient catalyst in the C―S coupling of various aryl halides with thiols. Moreover, the catalyst was easily recovered from the reaction mixture by simple filtration and recycled with almost consistent activity.