Synlett

A novel method for assembling pyrrolidine-2,4-diones from 1,5-enenitriles and acetone/acetonitrile via a cyclization/hydrolysis has been established under metal-catalyst- and base-free conditions, with Oxone as a green oxidant and H2O as an additive at 90–110 ℃. This strategy is highlighted by cyclization/hydrolysis of alkyl cyanides, achieving direct C(sp3)–H oxidative functionalization, and giving full conversion of the substrates with excellent functional group compatibility.

We report on the use of anthracene α-diketone as a source of carbon monoxide (CO) in carbonylation reactions. Photoirradiation by a 5 W blue LED of a diyne in the presence of anthracene α-diketone and a rhodium(I) catalyst resulted in a [2+2+1]-carbonylative cycloaddition of the diyne to CO released from the anthracene α-diketone to give a high yield (up to 99%) of the corresponding cyclopentadienone. This is the first demonstration of a CO-gas-free carbonylation reaction using anthracene α-diketone. Light irradiation was a major factor both in the generation of CO from anthracene α-diketone and in the catalytic activity. A halogen lamp, a fluorescent lamp, or sunlight also served as a light source for this reaction. With this system, there is no need for an additional reagent for generating CO.

A desulfonylative homocoupling of benzylic sulfone derivatives through a photoredox Ir catalyst is described. The 3,5-bis(trifluoromethyl)phenyl group is an effective substituent on sulfonyl group in this reaction, providing the structurally diverse multiply arylated ethanes in good yields. The α-deuterated or α-fluorinated sulfones, which can be readily prepared by α-functionalization, were also applicable, highlighting an avenue to synthesize medicinally important structures.

We discovered that the aluminosilicate-stabilized silyl cations, which were created from a solid-acid catalyst, the proton-exchanged montmorillonite, and Et3SiH, efficiently promoted the reductive benzylation of benzenes with aromatic carboxylic acid chlorides and Et3SiH in one pot.

We have developed a useful synthetic route to a 6/5/6/5/6-oxacyclic ring system and bipentalene derivatives from dimeric 7-oxonorbornene derivatives by using ring-rearrangement metathesis as a key step. This method provides access to fused oxacycles containing eight stereogenic centers in just three steps and to bipentalene derivatives in two steps only.

The encounter complex, i.e., the pre-organized assembly consisting of a Lewis acid and a Lewis base, is a fundamental concept in frustrated Lewis pair (FLP) chemistry. However, this donor–acceptor complex is challenging to study due to its transient nature. Here, we present a combined theoretical and experimental investigation on the potential isolation of an encounter complex enabled by enhancement of London dispersion forces between a sterically encumbered Lewis acid and base pair. Guided by computational analyses, the FLP originating from the bulky triarylamine N(3,5-tBu2C6H3)3 and the novel triarylborane B(3,5-tBu2C6H3)3 was investigated, leading to the isolation of a 1:1 co-crystal of both FLP components.

An account of our development of reactions to construct N-heterocycles by triggering cyclization–migration tandem reactions from aryl azides, nitroarenes, and aryl amines is described. The reactivity patterns of metal N-aryl nitrenes, nitrosoarenes, N-aryl nitrogen radical anions, and N-aryl nitrenoids are compared.1 Introduction2 Unlocking the Reactivity Embedded in Aryl Azides3 Exploiting the Reactivity of Nitrosoarenes Generated from Nitroarenes4 Radical Anion N-Aryl Nitrogen Reactive Intermediates from Nitroarenes5 Oxidation of Aryl Amines to Access Electrophilic N-Aryl Nitrenoids6 Conclusion

Crystalline porous materials have received extensive attention due to their fascinating structures and wide range of applications. We report a novel diphase two-dimensional (2D) halogen-bonded organic framework (XOF-TPP) based on 1,3,6,8-tetra(pyridin-4-yl)pyrene (TPP). XOF-TPP was constructed through [N···I+···N] interactions between the pyridyl groups of TPP and iodonium cations. The formation of XOF-TPP was monitored by X-ray photoelectron spectroscopy, IR spectroscopy, powder X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy, and simulated theoretically. Small-angle X-ray scattering indicated that the XOF-TPP exists as a 2D periodic structure. This diphase 2D halogen-bonded organic framework has promise for practical applications in supramolecular functional materials.

Deep learning is widely used in chemistry and can rival human chemists in certain scenarios. Inspired by molecule generation in new drug discovery, we present a deep-learning-based approach to reaction generation with the Trans-VAE model. To examine how exploratory and innovative the model is in reaction generation, we constructed the dataset by time splitting. We used the Michael addition reaction as a generation vehicle and took these reactions reported before a certain date as the training set and explored whether the model could generate reactions that were reported after that date. We took 2010 and 2015 as time points for splitting the reported Michael addition reaction; among the generated reactions, 911 and 487 reactions were applied in the experiments after the respective split time points, accounting for 12.75% and 16.29% of all reported reactions after each time point. The generated results were in line with expectations and a large number of new, chemically feasible, Michael addition reactions were generated, which further demonstrated the ability of the Trans-VAE model to learn reaction rules. Our research provides a reference for the future discovery of novel reactions by using deep learning.

An analysis of nucleoside active metabolite potencies against Hepatitis C virus (HCV) versus their parent ground-state energetic conformational bias as calculated by density functional theory suggested that nucleotides with a small difference between their antipodal energies are more likely to have potent antiviral activity compared to those with larger energetic differences. This energetic conformational bias was thought to be manipulated with substitutions along the ­ribofuranose ring. From 2′-C-methyluridine, a representative nucleoside with fair anti-HCV activity, two C3′ modifications in particular (ethyne and methyl) showed contrasting antipodal biases relative to each other while originating from a common synthetic intermediate, allowing a test of reasonable extremes of the computational model with a divergent nine-step synthesis. Antiviral activity of the compounds contradicted that suggested by the model, indicating a need for further refinement with additional biostructural considerations.