Representing an important class of ubiquitous chemical feedstock, aromatics have been extensively utilized in the nucleophilic aromatic substitution (SNAr) reactions, nitration reactions, Friedel-Crafts alkylation and acylation reactions, cross-coupling reactions, C-H bond functionalization reactions etc. Dearomatization reaction is another type of transformations of aromatics, in which their aromaticity is destroyed or reduced. Since its first report, dearomatization reaction has served as an efficient platform to create C(sp(3))-H-rich spiro, fused and bridged polycyclic structures, widely applied in material and medicinal chemistry. In the past two decades, various dearomatization reactions have been established by using transition-metal catalysis, organocatalysis, enzymatic catalysis, photocatalysis, and electrocatalysis. Diverse polycyclic structures have been obtained by the dearomatization of indoles, pyrroles, (benzo)furans, (benzo)thiophenes, quinolines, pyridines, benzenes, naphthalenes, etc. The coupling reagents, including nucleophiles, electrophiles, dipoles, radicals, and carbenes have been developed to assemble different functional groups on dearomative framework. In this review, we briefly summarized the developed dearomatization reactions, which were categorized by the kinds of aromatic compounds. The remaining challenges and perspectives on the future development of dearomatization reactions are also included here.

Ethylene coordination copolymerization with vinyl polar monomers, particularly short chain alkenols, offers an attractive method for controlled synthesis of important hydroxy-functionalized polyethylenes under mild conditions. However, reports on short-chain alkenol copolymerization are limited due to issues like chelating coordination and beta-O elimination. Here, we report the synthesis and characterization of binuclear Ni complexes for ethylene copolymerization with various alkenol monomers such as allyl-OH, 3-buten-1-ol, 4-penten-1-ol and 9-decen-1-ol. These complexes, upon activation with Et2AlCl, achieved notable activity (as high as 592 kg (mol cat h atm)-1) in ethylene/3-buten-1-ol copolymerization, producing copolymers with 1.7 mol% comonomer incorporation and a high molecular weight (Mn = 64.2 kg mol-1). The activity and comonomer content were influenced by Et2AlCl loading, reaction temperature, and alkenol monomer length, with longer alkenols such as 9-decen-1-ol yielding higher activity, comonomer incorporation and molecular weight. Activities up to 169 kg (mol cat h atm)-1 were also achieved in ethylene/allyl-OH copolymerization with reduced molecular weight (Mn = 17.2 kg mol-1). Microstructural analysis revealed predominant in-chain and chain-end polar monomer incorporation in all cases. Notably, ethylene/allyl-OH copolymers exhibited unique olefinic end groups and microstructures assignable to Friedel-Crafts reactions, which is likely due to an alternative chain termination pathway associated with the short chain length between the O atom and the active Ni center. For comparison, ethylene/allyl-OAc copolymers showed exclusively olefinic groups, indicating a beta-OAc elimination mechanism. This process resulted in lower activity and molecular weight, suggesting catalyst poisoning from rapid chain termination.

Two functional monomers containing thermo-crosslinkable benzocyclobutene and allyl groups and a bisphenol unit as a linker have been successfully synthesized. Powder X-ray diffraction indicates the monomers keep a complete amorphous state. DSC traces exhibit that the monomers have no melting point while display glass transition. Casting the solutions of the monomers in toluene into the surface of glass sheets forms smooth films. These data imply these monomers are molecular glasses due to their typical glass-forming behavior. Thermally cross-linked products based on the monomers exhibit good dielectric properties and low water uptake. Among these cross-linked monomers, the fluoro-containing resin displays better properties with a dielectric constant (Dk) of 2.74 and a dielectric loss (Df) of 1.89 x 10-3 at a frequency of 10 GHz, as well as exhibits a water uptake of 0.34 %. A control test indicates that the chemical structure of the bisphenol linker plays a crucial role for the formation of molecular glasses. When the linker is a rigid rod unit such as biphenyl group, the molecule does not exhibit molecular glass characteristics.

CuI/6-hydroxy picolinohydrazide-catalyzed coupling of (hetero)aryl chlorides with anilines proceeded well at 100 degrees C to afford biaryl amines in a diverse manner, which represents the first example of Cu-catalyzed biaryl amines under milder conditions. The same catalytic system could make the coupling of (hetero)aryl bromides with anilines work at room temperature, giving the corresponding products with an excellent reaction scope.