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The enantioselective desymmetrization of 2,2-disubstituted cyclohexane-1,3-diones has been realized through an unprecedented chiral-bisphosphine-catalyzed asymmetric Staudinger/aza-Wittig reaction. The key to this work’s success lies in utilizing an electronically rich and sterically hindered chiral bisphosphine reagent, namely DuanPhos, as a catalyst. In addition, a unique reductive system was established to address the requisite P^III/PV = O redox cycle. The mechanism of the chiral-bisphosphine-catalyzed asymmetric Staudinger/aza-Wittig reaction has been elucidated through combined computational and experimental studies. Several crinine-type amaryllidaceae alkaloids have been synthesized concisely, hinging on the newly developed methodology.

The bisoxindole motif is present in a variety of biologically active compounds. Here, we report an enantioselective oxidative homocoupling reaction of 2-oxindoles in the presence of a chiral bisguanidinium hypoiodite catalyst, providing access to the corresponding optically active bisoxindoles in excellent yields and with moderate to high diastereo- and enantioselectivities.

Thiuram disulfides undergo a Cu(I)-catalyzed C–S cross-coupling with aryl iodides through Cu(OAc)₂·H₂O-assisted desulfurization to produce the S-thiocarbamate ester compounds efficiently. Various aryl iodides containing diverse substituents underwent a smooth reaction with a series of cyclic and acyclic secondary amine-based thiuram disulfides under an open-air atmosphere. A probable mechanistic pathway has been suggested based on control experiments and reports from the literature.

A cascade reaction involving a base-promoted nucleophilic substitution reaction between diketones and α-bromoacetophenone derivatives and the subsequent selective condensation–cyclization was developed for the synthesis of 1,2-diaroyl benzofurans. 1,2-Diaroyl benzofurans with different functional groups and structures exhibit reversible photochromic behaviors in solution, solid state, and thin films with diverse colors, demonstrating a potential application in the field of optical functional materials.

Ketocalix[n]arenes can be prepared via oxidation of the methylene groups of protected calix[n]arenes. The presence of carbonyl groups at the bridges alters the preferred conformation and reactivity of the macrocycle and provides an entry point (via nucleophilic additions reactions) to a wide array of methylene-substituted derivatives as well as calix[n]radialenes.

1 Introduction

2 Synthesis of Ketocalix[n]arenes

2.1 Ketocalix[4]arene Derivatives

2.2 Systems Possessing both Carbonyl and Bromomethane Bridges

2.3 Pentaoxoketocalix[5]arene and Hexaoxoketocalix[6]arene Derivatives

2.4 Monooxo- and Dioxoketocalix[6]arenes

3 Conformation of Ketocalixarenes

4 Reactions of Ketocalixarenes

4.1 Alkylation of the OH Groups

4.2 Intramolecular Aromatic Nucleophilic Substitution

4.3 Reduction of the Carbonyl Groups

4.4 Reaction of 5c with PhLi

4.5 Reaction with tert-Butyllithium

5 From Ketocalix[n]arenes to Calix[n]radialenes and Calix[n]rotanes

6 Summary and Outlook

Twenty novel 4-bromocoumarin derivatives bearing a sulfonamide moiety were designed and synthesized. Their antiviral and antibacterial activities were systematically evaluated. The test results show that all the target compounds possess moderate to excellent antiviral and antibacterial activities. Among all target compounds, one compound exhibited good antiviral activity against TMV, CMV, and PVY, which is superior to ribavirin. Moreover, two target compounds exhibited good in vitro antibacterial activity against Psa, with an EC₅₀ value of 44.9 mg/L and 49.3 mg/L, respectively, which were better than thiodiazole copper and zinc thiazole, with an EC₅₀ value of 56.3 mg/L and 50.2 mg/L, respectively. The results provide insights for the development of multifunctional pesticides.

C-Aryl glycosides have attracted considerable interest as biologically active natural products and as O-aryl glycoside mimetics in drug discovery. Here, we describe a straightforward synthesis of C-aryl glycosides by photoredox/Ni dual-catalyzed reductive cross-coupling between glycosyl bromides and aryl bromides. This methodology enables a highly α-stereoselective synthesis of C-aryl glucosides, galactosides, and mannosides.

A triazine-based reagent, 2-hydroperoxy-4,6-dimorpholino-1,3,5-triazine (Triazox-II), was developed for alkene epoxidation. This reagent can be prepared from inexpensive starting materials (cyanuric chloride and morpholine) on a 15 mmol scale in two steps with 54% overall yield and isolated as a pure, bench-stable solid with low sensitivity to impact and friction. Triazox-II exhibited higher solubility in chlorinated solvents than the previously reported reagent Triazox. Epoxidation using Triazox-II was conducted in various solvents, with a preference for CH₂Cl₂ at 0.5 M concentration, resulting in epoxides in 83–94% yield. The reaction was conducted under mild conditions owing to the low acidity of the reaction coproduct.

Natural products containing highly oxygenated furanofuranone fragments are known for their potent biological activity, but also for their challenging total synthesis. In this study, the synthesis of five novel dephenylated (–)-goniofufurone analogues was completed and their cytotoxic activity against eight malignant and one normal human cell line was evaluated. Compared with previous syntheses of similar analogues, the synthesis was carried out starting from l-xylose, resulting in improved yields and a reduced number of synthetic steps for three divergent intermediates.

Numerous reports invoke Cu^III–F intermediates engaging in oxidative cross-couplings mediated by low/mid-valent copper and formal sources of ‘F⁺’ oxidants. These elusive and typically instable Cu^III fluorides have been rarely characterized or spectroscopically identified, making their existence and participation within catalytic cycles somehow questionable. We have authenticated a stable organocopper(III) fluoride that undergoes C_sp–CF₃ bond formation upon addition of silyl-capped alkynes following a 2 e^– Cu^III/Cu^I redox shuttle. This finding strongly supports the intermediacy of Cu^III fluorides in C–C coupling. We review herein the state of the art about well-defined Cu^III fluorides enabling cross-coupling reactions.

1 Introduction

2 Brief History of Coupling-Competent Cu^III Fluorides

3 Design of an Isolable – yet Reactive – Organocopper(III) Fluoride

4 Alkyne Trifluoromethylation: Scope and Mechanism

5 Extension to Aryl–CF₃ and C–Heteroatom Couplings

6 Summary and Outlook