Chiral Alkyl Halides: Underexplored Motifs in Medicine

The series of L-lysine-derived gelators-modified multifunctional chromatography stationary phase for separation of chiral and achiral compounds

In this study, using chiral L-lysine as the molecular skeleton, three kinds of L-lysine-derived gelators (GBLB, GBLF and GFLF) were synthesized and then bonded to the surface of silica matrix (5 μm) by amide condensation to prepare a series of multifunctional chromatography stationary phases (GBLB-SiO2, GBLF-SiO2, and GFLF-SiO2) were prepared. The L-lysine-derived gelators not only possess chiral recognition ability, but also can spontaneously form oriented and ordered network structures in liquid medium through the interaction of non-covalent bonding forces such as hydrogen bonding, π-π stacking, and van der Waals forces. The comprehensive effect of multiple weak interaction sites enhances the molecular recognition ability and further improves the separation diversity of different types of compounds on stationary phases. The separation and evaluation of chiral compounds showed that benzoin, 1-phenyl-ethanol, 1-phenyl-propanol and 6-hydroxyflavanone could be separated in normal phase mode (NPLC). The separation of different types of non-chiral compounds, such as sulfonamides, nucleosides, nucleobases, polycyclic aromatic hydrocarbons (PAHs), anilines, and aromatic acids, were achieved in hydrophilic interaction/reversed-phase/ion-exchange mode (HILIC/RPLC/IEC), and the separation of polarized compounds could be performed under the condition of ultrapure water as the mobile phase, which has the typical retention characteristics of per aqueous liquid chromatography (PALC). The effects of organic solvent content, temperature, pH value, and buffer salt concentration on the retention and separation performance of the column were investigated. Comparison of the three prepared columns showed that the separation performance (such as aromatic selectivity) could be improved by increasing the types of functional groups on the surface of the stationary phase and the number of aromatic groups. In a word, the prepared stationary phase have multiple retention properties, can simultaneously separate chiral compounds and various types of achiral compounds. This work provides an idea for developing multifunctional liquid chromatography stationary phase materials, and further expands the application of gelators in separation science.

Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

In this work, we describe the synthesis of halogenated pyran analogues of ᴅ-talose using a halo-divergent strategy from known 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-ᴅ-mannopyranose. In solution and in the solid-state, all analogues adopt standard 4 C 1-like conformations despite 1,3-diaxial repulsion between the F2 and the C4 halogen. Moreover, the solid-state conformational analysis of halogenated pyrans reveals deviation in the intra-annular torsion angles arising from repulsion between the axial fluorine at C2 and the axial halogen at C4, which increases with the size of the halogen at C4 (F < Cl < Br < I). Crystal packing arrangements of pyran inter-halides show hydrogen bond acceptor and nonbonding interactions for the halogen at C4. Finally, density functional theory (DFT) calculations corroborate the preference of talose analogues to adopt a 4 C 1-like conformation and a natural bonding orbital (NBO) analysis demonstrates the effects of hyperconjugation from C-F antibonding orbitals.

Photochemical direct alkylation of heteroarenes with alkanes, alcohols, amides, and ethers

Direct functionalization of heteroarenes with simple alkanes utilizing anthracene as a photoredox catalyst has been established. This approach provides a sustainable alternative, avoiding costly reagents or peroxides. The method demonstrates a broad substrate scope, enabling regioselective alkylation of various heteroarenes, including azoles, pyridines, quinolines, isoquinolones, and quinoxalinones under mild conditions. A range of alkyl sources, such as alkanes, ethers, dioxane, trioxane, alcohol, and alkylamides were viable substrates. A plausible catalytic cycle was proposed based on the preliminary mechanistic evidence.

Catalytic Asymmetric Mannich-Type Reaction of α-Haloacetonitriles

An asymmetric Mannich-type addition of aldimines and haloacetonitriles is reported here, yielding halogenated aminonitriles with excellent stereoselectivity, facilitated by a pincer Ni(II) complex as a catalyst. Haloacetonitriles are recognized as reactive electrophiles, and the possibility of their use as a pronucleophile has been almost neglected for many years. The resulting adduct can be readily converted into various valuable derivatives, including chiral aziridines, starting from chlorinated compounds.

Exploring putative drug properties associated with TNF-alpha inhibition and identification of potential targets in cardiovascular disease using machine learning-assisted QSAR modeling and virtual reverse pharmacology approach

Cardiovascular disease is a chronic inflammatory disease with high mortality rates. TNF-alpha is pro-inflammatory and associated with the disease, but current medications have adverse effects. Therefore, efficient inhibitors are urgently needed as alternatives. This study represents a structural-activity relationship investigation of TNF-alpha, curated from the ChEMBL database. Exploratory data analysis was performed to visualize the physicochemical properties of different bioactivity groups. The extracted molecules were subjected to PubChem and SubStructure fingerprints, and a QSAR-based Random Forest (QSAR-RF) model was generated using the WEKA tool. The QSAR random Forest model was built based on the SubStructure fingerprint with a correlation coefficient of 0.992 and 0.716 as the respective tenfold cross-validation scores. The variance important plot (VIP) method was used to extract the important features for TNF-alpha inhibition. The Substructure-based QSAR-RF (SS-QSAR-RF) model was validated using molecules from PubChem and ZINC databases. The generated model also predicts the pIC50 value of the molecules selected from the docking study followed by molecular dynamic simulation with the time step of 100 ns. Through virtual reverse pharmacology, we determined the main drug targets from the top four hit compounds obtained via molecular docking study. Our analysis included an integrated bioinformatics approach to pinpoint crucial targets like EGRF, HSP900A1, STAT3, PSEN1, AKT1, and MDM2. Further, GO and KEGG pathways analysis identified relevant cardiovascular disease-related pathways for the hub gene involved. However, this study provides valuable insights, it is important to note that it lacks experimental application. Future research may benefit from conducting in-vitro and in-vivo studies.

Markovnikov Hydrochlorination of Unactivated Alkenes with FeCl3 via a HAT/XAT Sequence

Hydrochlorination of alkenes is a practical strategy for accessing organic chlorides. Herein, we report the hydrochlorination of unactivated alkenes via a hydrogen atom transfer/halogen atom transfer process using earth-abundant and biocompatible FeCl3 as a chlorine source under extraordinarily mild reaction conditions. The protocol is easy to operate with notable features such as excellent chemoselectivity, remarkable efficiency, a broad substrate scope, and good functional group tolerance. Importantly, the synthetic utility is highlighted by scaled-up reactions, late-stage derivatizations of products, and the modification of sulfonamides.

Carbene-Catalyzed [4+2] Cycloaddition of Cyclobutenones and Isatins for Quick Access to Chiral Chlorine-Containing Spirocyclic δ-Lactones

Here we report a carbene-catalyzed enantio- and diastereoselective [4+2] cycloaddition reaction of cyclobutenones with isatins for the quick and efficient synthesis of spirocyclic δ-lactones bearing a chiral chlorine. A broad range of substrates with various substitution patterns proceed smoothly in this reaction, with the spirooxindole δ-lactone products afforded in generally good to excellent yields and optical purities under mild reaction conditions.

Regioselective C(sp2)-H halogenation of pyrazolo[1,5-a]pyrimidines facilitated by hypervalent iodine(iii) under aqueous and ambient conditions

An efficient and mild approach has been developed for the regio-selective direct C3 halogenation of pyrazolo[1,5-a]pyrimidines employing readily available potassium halide salts and a hypervalent iodine(iii) reagent at ambient temperature. The protocol is both practical and environmentally friendly, utilizing water as a green solvent, potassium halides as an inexpensive and bench stable halogen source and PIDA as a non-toxic reagent, enabling clean and efficient halogenation at room temperature. The procedure yields a range of C3 halogenated pyrazolo[1,5-a]pyrimidines in good to excellent yields. Mechanistic studies suggest the involvement of electrophilic substitution mechanism in the halogenation process.

Nickel-catalyzed γ-alkylation of cyclopropyl ketones with unactivated primary alkyl chlorides: balancing reactivity and selectivity via halide exchange

A novel method was developed for synthesizing γ-alkyl ketones via nickel-catalyzed cross-electrophile coupling of cyclopropyl ketones and non-activated primary alkyl chlorides. High reactivity and selectivity can be achieved with sodium iodide as a crucial cocatalyst that generates a low concentration of alkyl iodide via halide exchange, thus avoiding the formation of alkyl dimers. This reaction possessed excellent regioselectivity and high step economy circumventing in situ or pregenerated organometallics.

Organocatalytic Stereospecific Appel Reaction

Herein we report a new method for the catalytic Appel reaction by P(III)/P(V) redox cycling at very low catalyst loadings of 1-2 mol % using low amounts of hexachloroacetone as the halogen source and phenylsilane as the terminal reductant. Twenty-six alcohols and nine epoxides containing a wide variety of functional groups were converted to the respective chlorides and dichlorides in yields of up to 97%, enantiospecificities of up to >99%, and enantiomeric ratios of up to >99:1.

Decarboxylative halogenation of indoles by vanadium haloperoxidases

Halogenated heteroarenes are key building blocks across numerous chemical industries. Here, we report that vanadium haloperoxidases are capable of producing 3-haloindoles through decarboxylative halogenation of 3-carboxyindoles. This biocatalytic method is applicable to decarboxylative chlorination, bromination, and iodination in moderate to high yields and with excellent chemoselectivity.

Combined Lewis Acid Catalyzed Diastereoselective Halogenative Cascade Annulation of Enone-Tethered Cyclohexadienones

The cascade difunctionalization of α,β-unsaturated carbonyls by nucleophilic halogenation followed by enolate trapping with other electrophiles is highly challenging in synthetic organic chemistry. Herein, we report a chemo- and diastereoselective cascade annulation of enone-tethered cyclohexadienones by using an unconventional combined Lewis acid catalyzed halogenation reaction in the presence of an In(III)-catalyst and trimethylsilyl halide. The reaction provides highly functionalized bicyclic enones with four contiguous stereocenters.

Construction of Enantioenriched Quaternary C-Cl Oxindoles through Palladium-Catalyzed Asymmetric Allylic Substitution with Chloroenolates

A palladium-catalyzed asymmetric chloroenolate allylation with vinyl benzoxazinanones under mild reaction conditions has been developed, affording a series of optically active 3,3-disubstituted oxindoles exhibiting a chloro-group and a linear aryl amino side chain in good yields with up to 96% ee. Versatile functional group tolerance on the benzene ring has been demonstrated, and the utility of this method was probed by a scale-up synthesis and highlighted by product derivatizations.

Photoinduced activation of alkyl chlorides

In recent years, the activation of unactivated alkyl chlorides through light-induced processes has emerged as a promising field in radical chemistry, and has led to new transformations in organic synthesis. Direct utilization of alkyl chlorides as C(sp3)-hybridized electrophiles enables the facile construction of carbon-carbon and carbon-heteroatom bonds. Furthermore, recent studies in medicinal chemistry indicate that their presence is associated with high levels of success in clinical trials. This review summarizes the recent advances in the photoinduced activation of unactivated alkyl chlorides and discusses the mechanistic aspects underlying these reactions. We anticipate that this review will serve as a valuable resource for researchers in the field of unactivated chemical bond functionalization, and inspire considerable developments in organic chemistry, drug synthesis, materials science and other related disciplines.

Metal-Free Direct C3-H Alkylation and Arylation of Quinoxalin-2(1H)-Ones with Inert Alkyl and Aryl Chlorides

In the present manuscript, we reported the first visible-light-enabled direct C3-H alkylation/arylation of quinoxalin-2(1H)-ones with unactivated alkyl/aryl chlorides under metal-free conditions. A wide range of unactivated alkyl and aryl chlorides containing different functionalities are coupled with a variety of quinoxalin-2(1H)-one derivatives under mild reaction conditions to afford the C3-alkyl/aryl substituted quinoxalin-2(1H)-ones in moderate to good yields.

How Is Substrate Halogenation Triggered by the Vanadium Haloperoxidase from Curvularia inaequalis?

Vanadium haloperoxidases (VHPOs) are unique enzymes in biology that catalyze a challenging halogen transfer reaction and convert a strong aromatic C-H bond into C-X (X = Cl, Br, I) with the use of a vanadium cofactor and H₂O₂. The VHPO catalytic cycle starts with the conversion of hydrogen peroxide and halide (X = Cl, Br, I) into hypohalide on the vanadate cofactor, and the hypohalide subsequently reacts with a substrate. However, it is unclear whether the hypohalide is released from the enzyme or otherwise trapped within the enzyme structure for the halogenation of organic substrates. A substrate-binding pocket has never been identified for the VHPO enzyme, which questions the role of the protein in the overall reaction mechanism. Probing its role in the halogenation of small molecules will enable further engineering of the enzyme and expand its substrate scope and selectivity further for use in biotechnological applications as an environmentally benign alternative to current organic chemistry synthesis. Using a combined experimental and computational approach, we elucidate the role of the vanadium haloperoxidase protein in substrate halogenation. Activity studies show that binding of the substrate to the enzyme is essential for the reaction of the hypohalide with substrate. Stopped-flow measurements demonstrate that the rate-determining step is not dependent on substrate binding but partially on hypohalide formation. Using a combination of molecular mechanics (MM) and molecular dynamics (MD) simulations, the substrate binding area in the protein is identified and even though the selected substrates (methylphenylindole and 2-phenylindole) have limited hydrogen-bonding abilities, they are found to bind relatively strongly and remain stable in a binding tunnel. A subsequent analysis of the MD snapshots characterizes two small tunnels leading from the vanadate active site to the surface that could fit small molecules such as hypohalide, halide, and hydrogen peroxide. Density functional theory studies using electric field effects show that a polarized environment in a specific direction can substantially lower barriers for halogen transfer. A further analysis of the protein structure indeed shows a large dipole orientation in the substrate-binding pocket that could enable halogen transfer through an applied local electric field. These findings highlight the importance of the enzyme in catalyzing substrate halogenation by providing an optimal environment to lower the energy barrier for this challenging aromatic halide insertion reaction.

"Magic Chloro": Profound Effects of the Chlorine Atom in Drug Discovery

Chlorine is one of the most common atoms present in small-molecule drugs beyond carbon, hydrogen, nitrogen, and oxygen. There are currently more than 250 FDA-approved chlorine-containing drugs, yet the beneficial effect of the chloro substituent has not yet been reviewed. The seemingly simple substitution of a hydrogen atom (R = H) with a chlorine atom (R = Cl) can result in remarkable improvements in potency of up to 100,000-fold and can lead to profound effects on pharmacokinetic parameters including clearance, half-life, and drug exposure in vivo. Following the literature terminology of the "magic methyl effect" in drugs, the term "magic chloro effect" has been coined herein. Although reports of 500-fold or 1000-fold potency improvements are often serendipitous discoveries that can be considered "magical" rather than planned, hypotheses made to explain the magic chloro effect can lead to lessons that accelerate the cycle of drug discovery.

Naturally Occurring Organohalogen Compounds-A Comprehensive Review

The present volume is the third in a trilogy that documents naturally occurring organohalogen compounds, bringing the total number-from fewer than 25 in 1968-to approximately 8000 compounds to date. Nearly all of these natural products contain chlorine or bromine, with a few containing iodine and, fewer still, fluorine. Produced by ubiquitous marine (algae, sponges, corals, bryozoa, nudibranchs, fungi, bacteria) and terrestrial organisms (plants, fungi, bacteria, insects, higher animals) and universal abiotic processes (volcanos, forest fires, geothermal events), organohalogens pervade the global ecosystem. Newly identified extraterrestrial sources are also documented. In addition to chemical structures, biological activity, biohalogenation, biodegradation, natural function, and future outlook are presented.

Catalytic Chemo-, Regio-, Diastereo-, and Enantioselective Bromochlorination of Unsaturated Systems Enabled by Lewis Base-Controlled Chloride Release

A new strategy is described for the Lewis base-catalyzed bromochlorination of unsaturated systems that is mechanistically distinct from prior methodologies. The novelty of this method hinges on the utilization of thionyl chloride as a latent chloride source in combination with as little as 1 mol % of triphenylphosphine or triphenylphosphine oxide as Lewis basic activators. This metal-free, catalytic chemo-, regio-, and diastereoselective bromochlorination of alkenes and alkynes exhibits excellent site selectivity in polyunsaturated systems and provides access to a wide variety of vicinal bromochlorides with up to >20:1 regio- and diastereoselectivity. The precision installation of Br, Cl, and I in various combinations is also demonstrated by simply varying the commercial halogenating reagents employed. Notably, when a chiral Lewis base promoter is employed, an enantioselective bromochlorination of chalcones is possible with up to a 92:8 enantiomeric ratio when utilizing only 1-3 mol % of (DHQD)₂PHAL.

Photoredox Activation of Inert Alkyl Chlorides for the Reductive Cross-Coupling with Aromatic Alkenes

The inertness of chloroalkanes has precluded them as coupling partners for cross-coupling reactions. Herein we disclose a general strategy for the activation of inert alkyl chlorides through photoredox catalysis and their use as coupling partners with alkenes. The catalytic system is formed by [Ni(OTf)(Py₂ ^Ts tacn)](OTf) (1_Ni ), which is responsible for the Csp³ -Cl bond activation, and [Ir(^NMe2 bpy)(ppy)₂ ]PF_6, (PC_Ir ^NMe2 ), which is the photoredox catalyst. Combined experimental and theoretical studies show an in situ photogenerated Ni^I intermediate ([Ni(Py₂ ^Ts tacn)]⁺ ) which is catalytically competent for the Csp³ -Cl bond cleavage via a S_N 2 mechanism for primary alkyl chlorides, forming carbon-centered free radicals, which react with the olefin leading to the formation of the Csp³ -Csp³ bond. These results suggest inert alkyl chlorides can be electrophiles for developing new intermolecular strategies in which low-valent aminopyridine nickel complexes act as key catalytic species.

What Drives Radical Halogenation versus Hydroxylation in Mononuclear Nonheme Iron Complexes? A Combined Experimental and Computational Study

Nonheme iron halogenases are unique enzymes in nature that selectively activate an aliphatic C–H bond of a substrate to convert it into C–X (X = Cl/Br, but not F/I). It is proposed that they generate an Fe^III(OH)(X) intermediate in their catalytic cycle. The analogous Fe^III(OH) intermediate in nonheme iron hydroxylases transfers OH^• to give alcohol product, whereas the halogenases transfer X^• to the carbon radical substrate. There remains significant debate regarding what factors control their remarkable selectivity of the halogenases. The reactivity of the complexes Fe^III(BNPA^Ph2O)(OH)(X) (X = Cl, Br) with a secondary carbon radical (R^•) is described. It is found that X^• transfer occurs with a secondary carbon radical, as opposed to OH^• transfer with tertiary radicals. Comprehensive computational studies involving density functional theory were carried out to examine the possible origins of this selectivity. The calculations reproduce the experimental findings, which indicate that halogen transfer is not observed for the tertiary radicals because of a nonproductive equilibrium that results from the endergonic nature of these reactions, despite a potentially lower reaction barrier for the halogenation pathway. In contrast, halogen transfer is favored for secondary carbon radicals, for which the halogenated product complex is thermodynamically more stable than the reactant complex. These results are rationalized by considering the relative strengths of the C–X bonds that are formed for tertiary versus secondary carbon centers. The computational analysis also shows that the reaction barrier for halogen transfer is significantly dependent on secondary coordination sphere effects, including steric and H-bonding interactions.

Recent Progresses in the Preparation of Chlorinated Molecules: Electrocatalysis and Photoredox Catalysis in the Spotlight

Among halogenated molecules, those containing chlorine atoms are fundamental in many areas such as pharmaceuticals, polymers, agrochemicals and natural metabolites. Despite the fact that many reactions have been developed to install chlorine on organic molecules, most of them rely on toxic and hazardous chlorinating reagents as well as harsh conditions. In an attempt to move towards more sustainable approaches, photoredox catalysis and electrocatalysis have emerged as powerful alternatives to traditional methods. In this review, we collect the most recent and significant examples of visible-light- or current-mediated chlorination published in the last five years.

Highly stereoselective synthesis of spirocyclopropylthiooxindoles and biological evaluation

We present a novel highly stereoselective Rh-catalyzed cyclopropanation of diazothiooxindoles with a broad range of α-functionalized styrenes, enabling facile access of chiral spirocyclopropylthiooxindoles in high to excellent enantiomeric excess.

Potential of Hibiscus sabdariffa L. Calyx (Rosella) extract as antibacterial agent in dental disease: Phytochemical and chemical components profiling

Chemical characteristics of natural products are influenced by different external factors, varying according to the geographic origin. The ethanol extract of Hibiscus sabdariffa L calyx Indonesia has been studied in vivo and in vitro provide potential effect for dental field uses. Ethanol extract showed antibacterial to Streptococcus sanguinis as an inducer gingivitis, had an effect on the treatment of oral mucosa ulceration, and could inhibit the development of alveolar bone destruction. This study aims to determine the chemical groups and components of ethanol extract of H. sabdariffa L. calyces (Indonesia origin). Chemical group of ethanol extract H. sabdariffa L calyx Indonesia was analysis through phytochemical screening, whereas chemical components were detected through gas chromatography-mass spectrometry analysis. Saponins, tannins, phenolic, flavonoids, triterpenoids and glycosides, and 17 chemical components were identified in the ethanol extract of H. sabdariffa L calyx Indonesia. Among the chemical components, fatty acids group showed the most dominant. For standardization and develop of oral drug preparation, a better chemical components and phytochemical profiling are essential because the extract quality of herbs has various quality.

Fundamental curiosity of multivicinal inter-halide stereocenters

A stereoselective strategy allowed the striking impact of a single halogen on the physical properties of inter-halide alkane units to be unravelled.

Synthesis, Anticancer Activity, Structure-Activity Relationship, and Molecular Modeling Studies of α-Mangostin Derivatives as hERα Inhibitor

α-Mangostin is one of the secondary metabolites in mangosteen pericarp, which has been reported to have anti-breast cancer activity. In our previous study, three α-mangostin derivatives were computationally designed as hERα antagonists. In this present study, the designed compounds were synthesized undergoing a benzoylation reaction between α-mangostin with three benzoyl chloride derivatives to produce three derivatives, namely, AMB-1, AMB-2, and AMB-10. The synthesized compounds were then evaluated for their antiproliferative activity against the MCF-7 breast cancer cell model with hERα as the protein target. The in vitro assay shows moderate activity (57-126 μM) for all derivatives. The dynamic behaviors of all ligands, including α-mangostin and 4-hydroxytamoxifen (4-OHT), were studied with 100 ns of MD simulation. The structure-activity relationship shows that although it does not entirely concord with the expected design, it can explain the trend of α-mangostin and its derivatives antiproliferative activities against MCF-7, which associates with hERα antagonism.

Total Syntheses of Vicinal Dichloride Monoterpenes Enabled by Aza-Belluš-Claisen Rearrangement

Diastereoselective syntheses of syn- and anti-vicinal dihalides were achieved via an aza-Belluš-Claisen rearrangement, which involved the reaction of an α-chloro carboxylic acid chloride with halogen-substituted trans-allyl morpholines in the presence of Lewis acids. The developed method was used for the total synthesis of a group of monoterpene natural products bearing vicinal dichloride subunits.

Asymmetric synthesis of chiral organosilicon compounds via transition metal-catalyzed stereoselective C-H activation and silylation

This feature article details the progress of transition metal-catalyzed stereoselective sp² and sp³ C-H activation and silylation in the synthesis of chiral organosilicon compounds, and the asymmetric C-H silylation includes intramolecular cyclizing silylation and intermolecular silylation. The silylating reagents include monohydrosilanes, dihydrosilanes, silacylcobutanes and disilanes. In general, catalytic systems include a transition metal salt as the catalyst and a chiral ligand. No external chiral ligand is required in some cases where the chiral substrates act as the source of chirality. Many kinds of silylated compounds with central, axial, planar, or helical chirality have been constructed via C-H activation by asymmetric rhodium, iridium or palladium catalysis. Some pharmacophores and material building blocks were successfully introduced into the target molecules. Some silylated products proved to be useful in medicinal chemistry, synthetic organic chemistry, and materials science. Besides reaction development, mechanisms for stereoselective C-H activation and silylation are also discussed.

VUV-Induced Photodissociation of the Chloroacetone Molecule Studied by Photoelectron-Photoion Coincidence Spectroscopy

The dissociative photoionization dynamics of the chloroacetone molecule (C₃H₅OCl) in the gas phase, induced by vacuum ultraviolet (VUV) synchrotron radiation in the range from 10.85 to 21.50 eV, has been investigated by using time-of-flight mass spectrometry in the photoelectron-photoion coincidence mode. The appearance energies for the most relevant cation fragments produced in this energy range have been analyzed, and the fragmentation pathways leading to the formation of the cation species have been proposed and discussed. The mass spectra show that the most dominant VUV photodissociation cation product appears at m/z 43 and has been assigned to the C₂H₃O⁺ species. Enthalpies of formation (Δ_fH°_0K) for the neutral chloroacetone molecule and its molecular cation have been derived and correspond to -207.8 ± 5.8 kJ/mol and 755.1 ± 6.8 kJ/mol, respectively. In addition to the spectral analysis, the structural and energetic parameters for the cations produced have also been examined on the basis of high-level quantum chemical numerical calculations.

In Search of Effective Anticancer Agents-Novel Sugar Esters Based on Polyhydroxyalkanoate Monomers

Cancer is one of the deadliest illness globally. Searching for new solutions in cancer treatments is essential because commonly used mixed, targeted and personalized therapies are sometimes not sufficient or are too expensive for common patients. Sugar fatty acid esters (SFAEs) are already well-known as promising candidates for an alternative medical tool. The manuscript brings the reader closer to methods of obtaining various SFAEs using combined biological, chemical and enzymatic methods. It presents how modification of SFAE's hydrophobic chains can influence their cytotoxicity against human skin melanoma and prostate cancer cell lines. The compound's cytotoxicity was determined by an MTT assay, which followed an assessment of SFAEs' potential metastatic properties in concentrations below IC50 values. Despite relatively high IC50 values (63.3-1737.6 μM) of the newly synthesized SFAE, they can compete with other sugar esters already described in the literature. The chosen bioactives caused low polymerization of microtubules and the depolymerization of actin filaments in nontoxic levels, which suggest an apoptotic rather than metastatic process. Altogether, cancer cells showed no propensity for metastasis after treating them with SFAE. They confirmed that lactose-based compounds seem the most promising surfactants among tested sugar esters. This manuscript creates a benchmark for creation of novel anticancer agents based on 3-hydroxylated fatty acids of bacterial origin.

Vicinal halo-trifluoromethylation of alkenes

Both trifluoromethyl and halide groups are widely found in medicinally and pharmaceutically important compounds and, moreover, organohalides are commonly used as versatile intermediates in synthetic organic chemistry. Due to their prevalence and easy accessibility, alkene halo-trifluoromethylation provides a convenient way to install these valuable functionalities in complex targets. In this review, we summarize recent advances and achievements in this fast-growing research field. For clarity, the reactions were classified according to the type of halogen atom.

Site Selective Chlorination of C(sp3 )-H Bonds Suitable for Late-Stage Functionalization

C(sp³ )-Cl bonds are present in numerous biologically active small molecules, and an ideal route for their preparation is by the chlorination of a C(sp³ )-H bond. However, most current methods for the chlorination of C(sp³ )-H bonds are insufficiently site selective and tolerant of functional groups to be applicable to the late-stage functionalization of complex molecules. We report a method for the highly selective chlorination of tertiary and benzylic C(sp³ )-H bonds to produce the corresponding chlorides, generally in high yields. The reaction occurs with a mixture of an azidoiodinane, which generates a selective H-atom abstractor under mild conditions, and a readily-accessible and inexpensive copper(II) chloride complex, which efficiently transfers a chlorine atom. The reaction's exceptional functional group tolerance is demonstrated by the chlorination of >30 diversely functionalized substrates and the late-stage chlorination of a dozen derivatives of natural products and active pharmaceutical ingredients.

The Suzuki–Miyaura reaction of BPin-substituted F-BODIPYs with aryl halides

F-BODIPYs substituted with BPin functionality have been coupled to aryl halides using a mild and efficient catalyst system involving Pd2(dba)3 and XPhos. The methodology enables the Suzuki–Miyaura cross-coupling of electron-rich, electron-poor, and sterically encumbered BPin-substituted F-BODIPYs to aryl halides bearing various functional groups, thus presenting an opportunity for the preparation of highly functionalised F-BODIPYs without need for the corresponding aryl moiety to be available in borylated form.

Reframing primary alkyl amines as aliphatic building blocks

While primary aliphatic amines are ubiquitous in natural products, they are traditionally considered inert to substitution chemistry. This review highlights historical and recent advances in the field of aliphatic deamination chemistry which demonstrate these moieties can be harnessed as valuable C(sp3) synthons. Cross-coupling and photocatalyzed transformations proceeding through polar and radical mechanisms are compared with oxidative deamination and other transition metal catalyzed reactions.

Electrohalogenation of organic compounds

In this review we target sp, sp² and sp³ carbon fluorination, chlorination, bromination and iodination reactions using electrolysis as a redox medium. Mechanistic insights and substrate reactivity are also discussed.

Phenolate anion-catalyzed direct activation of inert alkyl chlorides driven by visible light

A photochemical activation of inert alkyl chlorides catalyzed by phenolate anions was developed for C–O bond formation, dehalogenation, and cyclization under mild conditions.

Hydrogen-Bond-Donor Solvents Enable Catalyst-Free (Radio)-Halogenation and Deuteration of Organoborons

A hydrogen bond donor solvent assisted (radio)halogenation and deuteration of organoborons has been developed. The reactions exhibited high functional group tolerance and needed only an ambient atmosphere. Most importantly, compared to literature methods, our conditions are more consistent with the principals of green chemistry (e.g., metal-free, strong oxidant-free, more straightforward conditions).