Synlett

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.

Herein, we report strain-driven regioselective tandem ring-opening cross-metathesis (ROCM) of a linearly fused cage system that contains both bicyclo[2.2.1]heptene and bicyclo[2.2.2]octene units fused to the same cage system. The synthesis of novel cage propellane involves Diels–Alder cycloaddition and [2+2] photocycloaddition as key steps.

Synlett 2022; 33: V-DOI: 10.1055/s-0042-1752341Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents

A simple protocol catalyzed by a Brønsted acid, trifluoromethanesulfonic acid (CF3SO3H), to synthesize conjugated diene-diones from easily accessible tertiary propargyl alcohols and 1,3-dicarbonyl compounds is described. Reactions are performed in an air atmosphere by using undried solvents with water being the environmentally benign side product of the process. Preliminary synthetic applications of the conjugated diene-diones in the formation of conjugated dieneones and furans are also reported herein.

We report a highly branch-selective and enantioselective allylic alkylation of simple ketones with racemic aliphatic allylic carbonates under mild conditions. By using a Rh–bisoxazolinephosphine system and catalytic amounts of a base in THF, a series of chiral β-branched γ,δ-unsaturated ketones were obtained with excellent regio- and enantioselectivities. An outer-sphere nucleophilic substitution C–C bond-formation process is proposed on the basis of mechanistic studies.

A rhodium(III)-catalyzed transfer hydrogenation of unsaturated ketones was developed. The simple catalytic system could be used for the 1,4-reduction of unsaturated cyclic, acyclic ketones, diketones, as well as β-ketoester, and a variety of functional groups were well-tolerated, affording products in moderate to excellent yields.

A synthetic strategy based on the application of three consecutive ring-expansion reactions has been used in the synthesis of analogues of the macrocyclic core of the solomonamide natural products. Starting from a simple, readily available tetrahydrocarbazole, oxidative ring expansion is followed by two further 3- and 4-atom ring-expansion reactions, enabling the insertion of amino acid and hydroxy acid derived linear fragments into 15- to 17-membered-ring-enlarged macrocyclic products.

We present a combined experimental and computational study on the thermodynamic stability of cis- and trans-alkenes substituted with dispersion energy donor (DED) groups. To investigate the role of noncovalent interactions on equilibrium of cis- and trans-alkenes we utilized hydrochlorination reactions. While the general assumption is that increasing steric bulk favors the trans-alkene, we observe an equilibrium shift towards the more crowded cis-alkene with increasing substituent size. With the aim to quantify noncovalent interactions, we performed a double mutant cycle to experimentally gauge the attractive potential of bulky substituents. Additionally, we utilized local energy decomposition analysis at the DLPNO-CCSD(T)/def2-TZVP level of theory. We found LD interactions and Pauli exchange repulsion to be the most dominant components to influence cis- and trans-alkene equilibria.