Iron‐Catalyzed Alkene Trifluoromethylation in Tandem with Phenol Dearomatizing Spirocyclization: Regioselective Construction of Trifluoromethylated Spirocarbocycles

Diverse Synthesis of Arene-Fused [n.1.1]-Bridged Molecules via Catalytic Cycloaddition and Rearrangement Reactions

Although great advancement has been made in synthesis of 3D bridged bicyclic[n.1.1]-bioisosteres, facile construction of 2D/3D merged molecules incorporating bridged rings, as novel chemical space in drug discovery, remains a significant challenge. Herein a collective, selective, and diversity-oriented approach for up to 6 types of 2D/3D polycyclic scaffolds featuring bicyclo[n.1.1] substructure is reported. A boronyl radical-catalyzed [2σ+2π] cycloaddition between bicyclo[1.1.0]butanes and ortho-quinone methides afforded spirocyclic compounds containing a bicyclo[2.1.1]hexanes unit, which were used as intermediates for synthesis of three types of 2D/3D scaffolds via judiciously controlled Lewis acid-catalyzed rearrangements. The reaction and rearrangement of para-quinone methides worked analogously and provided another two polycyclic scaffolds.

Recent Progress in Synthetic Applications of Hypervalent Iodine(III) Reagents

Hypervalent iodine(III) compounds have found wide application in modern organic chemistry as environmentally friendly reagents and catalysts. Hypervalent iodine reagents are commonly used in synthetically important halogenations, oxidations, aminations, heterocyclizations, and various oxidative functionalizations of organic substrates. Iodonium salts are important arylating reagents, while iodonium ylides and imides are excellent carbene and nitrene precursors. Various derivatives of benziodoxoles, such as azidobenziodoxoles, trifluoromethylbenziodoxoles, alkynylbenziodoxoles, and alkenylbenziodoxoles have found wide application as group transfer reagents in the presence of transition metal catalysts, under metal-free conditions, or using photocatalysts under photoirradiation conditions. Development of hypervalent iodine catalytic systems and discovery of highly enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important recent achievement in the field of hypervalent iodine chemistry. Chemical transformations promoted by hypervalent iodine in many cases are unique and cannot be performed by using any other common, non-iodine-based reagent. This review covers literature published mainly in the last 7-8 years, between 2016 and 2024.

The TaCl5-Mediated Reaction of Dimethyl 2-Phenylcyclopropane-1,1-dicarboxylate with Aromatic Aldehydes as a Route to Substituted Tetrahydronaphthalenes

It is found that the reaction of dimethyl 2-phenylcyclopropane-1,1-dicarboxylate with 2 equivalents each of aromatic aldehydes and TaCl5 in 1,2-dichloroethane at 23 °C for 24 h after hydrolysis gives substituted 4-phenyl-3,4-dihydronaphtalene-2,2(1H)-dicarboxylates in good yield. This represents a new type of reactions between 2-arylcyclopropane-1,1-dicarboxylates and aromatic aldehydes, yielding chlorinated tetrahydronaphthalenes with a cis arrangement of the aryl and chlorine substituents in the cyclohexene moiety. A plausible reaction mechanism is proposed.

Confinement Effect in Metal-Organic Framework Cu3()2 for Enhancing Shape Selectivity of Radical Difunctionalization of Alkenes

The radical difunctionalization of alkenes plays a vital role in pharmacy, but the conventional homogeneous catalytic systems are challenging in selectivity and sustainability to afford the target molecules. Herein, the famous readily available metal-organic framework (MOF), Cu3(BTC)2, has been applied to cyano-trifluoromethylation of alkenes as a high-performance and recyclable heterogeneous catalyst, which possesses copper(II) active sites residing in funnel-like cavities. Under mild conditions, styrene derivatives and various unactivated olefins could be smoothly transformed into the corresponding cyano-trifluoromethylation products. Moreover, the transformation brought about by the active copper center in confined environments achieved regio- and shape selectivity. To understand the enhanced selectivity, the activation manner of the MOF catalyst was studied with control catalytic experiments such as FT-IR and UV-vis absorption spectroscopy of substrate-incorporated Cu3(BTC)2, which elucidated that the catalyst underwent a radical transformation with the intermediates confined in the MOF cavity, and the confinement effect endowed the method with pronounced selectivities.

Metal-free electrochemistry promoted radical cascade cyclization to access CF3-containing benzimidazo[2,1-a]isoquinolin-6(5H)-ones

Using CF3SO2Na as the CF3 radical source, an eco-friendly approach for electrochemistry-mediated radical cascade cyclization of N-methacryloyl-2-phenylbenzoimidazoles was described. This reaction features mild reaction conditions, readily available substrates, and moderate to good yields through the construction of two C-C bonds in one step.

Recent Advances in Transition-Metal Mediated Trifluoromethylation Reactions

Fluorine compounds are known for their abundance in more than 20% of pharmaceutical and agrochemical products mainly due to the enhanced lipophilicity, metabolic stability and pharmacokinetic properties of organofluorides. Consequently,...