Synlett最新文献

A mild and efficient one-pot, three-component ball-mill-assisted reaction of aldehydes, anilines, and dihydrofuran (or dihydropyran and cyclohexenone) has been described for the first time in the presence of the catalytic amount of aqueous perchloric acid (8 mol%) at room temperature under organic solvent- and metal-free conditions. The reactions are fast (1 h), providing the products with excellent yields and high diastereoselectivity. This procedure endows a simple, efficient, and cost-effective method for the diastereoselective synthesis of furano- and pyrano-tetrahydroquinolines and phenanthridinone derivatives, which are important biological compounds. The diastereomers with cis configuration were isolated as major products. The H–H COSY, NOESY experiments and X-ray crystallographic analysis of selected compounds were performed to confirm the cis isomer. The synthesized tetrahydroquinolines have been evaluated in vitro for their antibacterial and anticancer activities, and it was found that both the prepared compounds showed significant antibacterial and anticancer properties.

A simple, cost-effective, and modular strategy has been developed to synthesize synthetically and pharmaceutically active enaminones by oxidative amination of aryl alkenes with amines and CHCl₃, using tert-butyl hydroperoxide as an oxidant. We describe the synthesis of enaminones from vinyl arenes and sterically hindered N,N-diisopropylethylamine (DIPEA) by employing an Earth-abundant cobalt salt as a catalyst within a very short reaction period for the first time. Furthermore, nitrogen- and oxygen-containing heterocyclic compounds have been synthesized from these highly functionalized enaminones. Moreover, various control experiments, such as radical trapping reaction, along with a Hammett analysis with various types of substituents on the styrene ring unraveled the detailed mechanism of this reaction pathway.

Aging alcohol is a timeless process that has seen little variation since the time of its invention. Molecules stored within the wood can be extracted by the alcohol to produce unique flavors. Among these molecules exist the whiskey and cognac lactones. Herein we report a short synthesis of the trans-whiskey and cognac lactones using a rearrangement of cyclopropane hemimalonates.

We report a one-pot base-free protocol for the oxidative olefination of benzylic amines promoted by a hypervalent iodine reagent for the synthesis of α,β-unsaturated ketones. Mechanistically, (diacetoxyiodo)benzene oxidizes the benzylic amine to the corresponding imine, which, on reaction with a phenacyl(triphenyl)phosphonium bromide salt and an in situ generated acetoxy anion leads to an α,β-unsaturated ketone. A wide range of α,β-unsaturated ketones were easily accessed through direct oxidative olefination of substituted benzylic amines in good to excellent yields and with high E-selectivity.

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.