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99mTc nitrido-Levetiracetam was prepared using the 99mTc nitrido core for labeling. The reaction conditions were optimized to get the highest radiochemical purity (98%): substrate amount 2 mg, Sn(II) (reducing agent) amount 50 µg, pH 7, 30 min, ambient temperature. The biodistribution studies revealed high brain uptake of 99mTc nitride-Levetiracetam, reaching a maximum of 9% ID/g at 30 min post injection (p.i.). The complex deserves further analysis as a candidate brain imaging agent.

A series of polymeric ionic liquids (PILs) used as effective heterogeneous catalysts for biodiesel production via esterification of free fatty acids (FFAs) were effectively prepared by the reaction of poly (ethylene imine) (PEI) polymers with different molecular weight and 1,3-propanesultone, followed by the further acidification with differential effective acids, i.e. H2SO4, CF3SO3H, CH3SO3H or p-toluenesulfonic acid (p-TSA). Ultrahigh acidity and catalytic performance were achieved and could be fine-tuned by simply adjusting the molecular weight of PEI and by further treatment of acids. Specifically, under the optimal conditions (i.e. reaction temperature was 70 °C, reaction time was 2.0 h, catalyst dosage was 3.15% (mass), and alcohol/acid molar ratio was 14:1) acquired through the Box-BEHNKEN response surface methodology, a high oleic acid conversion of 98.42% could be obtained over the optimal PIL, PEI(70000)-PS-p-TSA. Additionally, our PILs also showed high generality for esterification of other FFAs, with general high conversion over 90% noted in each case even under much milder reaction conditions compared to other conventional catalysts.

Acidity plays a vital role in methane conversion by co-feeding method, which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane. In this work, Zn, Ni, Mo, La, Ga, Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane. It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction. Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%, whose aromatic selectivity increases from 27.2% to 52.2% compared with that of HZSM-5. Besides, the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics (MTA) reaction.

α-difluoromethylornithine (DFMO) is an anti-Trypanosoma Brucei agent that is approved for the medication of sleeping sickness and is widely licensed for the treatment and diminishing the unwanted facial hair (hirsutism). The suggested work provides a comprehensive analytical protocol for investigating the fluorescence properties of the reaction product between DFMO and ninhydrin/phenylacetaldehyde reagent. In this approach, all reaction conditions such as reagent volumes, buffer volume, pH value, heating time and heating temperature were carefully handled and optimized. The formed product was measured spectrofluorimetrically at the emission wavelength of 483 nm upon its excitation at the wavelength of 388 nm. For accuracy, linearity, sensitivity, robustness and preciseness of the method, the suggested approach was validated and verified according to ICH guiding principles. Also, the proposed work offered a unique selectivity for the determination of DFMO with agreeable recovery values in different brands of commercial cream samples without interference from cream excipients. Lastly, the suggested approach was assured to be successful in the estimation of DFMO in human urine specimens with agreeable recovery results.

A practical and eco-friendly strategy for the radical-mediated decarboxylative [3 + 2] and [4 + 2] annulation of enynals and γ,σ-unsaturated N-(acyloxy)phthalimides through the photoactivation of an electron donor-acceptor (EDA) complex has been developed. A wide range of primary, secondary, and tertiary alkyl N-hydroxyphthalimide (NHP) esters can be used as suitable substrates for the synthesis of fused ketones without any transition-metal catalysts or oxidants. This protocol features a broad substrate scope, excellent selectivity, and clean reaction conditions.

The development of enantioselective desymmetrization of para-quinamines with isocyanates catalyzed by chiral phosphoric acid is reported. The strategy provides concise access to functionalized imidazolidin-2-one derivatives in high yields and enantioselectivities under mild reaction conditions. Remarkably, this reaction could be performed on a gram scale using 5 mol % catalyst loading and the chiral imidazolidin-2-one derivatives could be easily transformed into valuable scaffolds without disturbing the enantiopurity, demonstrating the synthetic utility of this protocol.

An SN2′ defluorinative allylation of trifluoromethylalkenes with readily available allylsilanes to access homoallyl gem-difluoroalkenes is reported. The reaction is triggered by a catalytic amount of TBAF, with the extruded fluoride in the reaction serving as a sustainable activator for organosilanes. The high efficiency, good functional group tolerance, and mild reaction conditions underline the potential of this method in synthetic chemistry.

Rh(III)-catalyzed regioselective trifluoromethylthiolation of the unactivated C(sp3)-H bond of 8-methylquinolines with bench-stable electrophilic trifluoromethylthiolating reagent via C(sp3)-H activation is explored. Various substituted 8-methylquinolines provided the products in good yields with high regioselectivity. Current reaction conditions are also applicable for the late-stage functionalization of natural molecule santonin and caffeine-substituted 8-methylquinoline.

A novel nickel-catalyzed highly selective reductive cross-coupling of alkyl bromides and chlorosilanes to construct the C-Si bond has been developed. Under benign reaction conditions, a series of structurally interesting organosilanes can be accessed without Ni-catalyzed isomerization. The utility of this chemistry is illustrated by further transformations of the product. Moreover, the radical mechanism of the reaction is illustrated by control experiments.

Direct enantioselective hydrogenation of unsaturated compounds to generate chiral three‐dimensional motifs is one of the most straightforward and important approaches in synthetic chemistry. We realized the Ru(II)‐NHC‐catalyzed asymmetric hydrogenation of 2‐quinolones under mild reaction conditions. Alkyl‐, aryl‐ and halogen‐substituted optically active dihydro‐2‐quinolones were obtained in high yields with moderate to excellent enantioselectivities. The reaction provides an efficient and atom‐economic pathway to construct simple chiral 3,4‐dihydro‐2‐quinolones. The desired products could be further reduced to tetrahydroquinolines and octahydroquinolones., Ruthenium‐NHC‐catalyzed asymmetric hydrogenation of 2‐quinolones to simple 3,4‐dihydro‐2‐quinolones has been developed with high yields and moderate to excellent enantioselectivities under mild conditions.

In this study, bromoalkyl glycosides were successfully synthesized in microreactor scale by Fischer glycosylation. Yields between 24 and 40% after purification were achieved using various acidic catalysts and conditions. In some experiments, yields 180% higher than with previously known methods could be achieved. This study showed also that reversed-phase flash chromatography is more successful than normal-phase flash chromatography for the purification of bromoalkyl glycosides. Furthermore, longer bromoalcohols were shown to be more compatible than shorter bromoalcohols under these reaction conditions.

An unprecedented Sc(OTf)3-catalyzed C2-selective cyanation/defluorination cascade of perfluoroalkylated 3-indolylmethanols with TMSCN is described, which provides a novel and practical strategy for the synthesis of structurally diverse 3-(2-cyano)-indolyl substituted gem-difluoroalkenes and β-fluoro-β-perfluoroalkylalkenes. The reaction features excellent regio- and stereoselectivity and broad substrate scope. Notably, the obtained gem-difluoroalkenes and β-fluoro-β-perfluoroalkylalkenes could be easily transformed into 3-fluoro(perfluoroalkyl)-β-carbolines with excellent efficiency simply by treating them with Grignard reagents or DIBAL-H under mild reaction conditions.

Bimetallic palladium-tin catalysts supported on microporous carbon (denoted as Pd-Sn(x)/C, loading amount of Pd = 5 wt% and x = Pd/Sn molar ratio; c.a. 3.0; 1.5; and 1.0) showed high selectivity in the hydrogenation of stearic acid towards 1-octadecanol (stearyl alcohol) under mild reaction conditions. Pd-Sn(x)/C catalysts were synthesized via the hydrothermal method at temperature of 150 °C for 24 h, and reduced with H2 at 400 °C for 3 h. Pd-Sn(1.5)/C catalyst exhibited the highest yield of stearyl alcohol (1-octadecanol) (up to 73.2%) at 100% conversion of stearic acid at temperature 240 °C, initial H2 pressure of 3.0 MPa, a reaction time of 13 h, and in 2-propanol/water solvent. The high selectivity of alcohols over Pd-Sn(1.5)/C catalyst can be attributed to the formation of bimetallic Pd-Sn alloy phases (e.g. Pd3Sn and Pd3Sn2) as obviously depicted by XRD analysis. The presence of co-promotor Sn and the formation of bimetallic may play a pivotal role in the high selectivity of 1-octadecanol. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A variety of N-vinylindoles and N-vinylpyrroles were prepared in moderate to good yields through the nickel(II)-catalyzed [3 + 2] cycloaddition of α,β-unsaturated nitrones with allenoates under mild reaction conditions. A rational mechanism for the formation of N-vinylindoles was proposed based on the 18O-labeled experiments and key intermediates detected by high-resolution mass spectrometry trace experiments. The present method highlights a nickel(II)-controlled cyclization, atom-economical reaction, broad substrate scope, good functional group tolerance, and high Z-stereoselectivity for the enamine bond.

Given the characteristics of the high content of phenols and poor biodegradability in lignite upgrading wastewater, the Fenton oxidation process was used as a pretreatment technology of the biochemical treatment process. Therefore, the best reaction conditions within the range of test conditions were investigated. The results show that the best reaction conditions of the Fenton oxidation system within the range tested are as follows: The ratio of H2O2/chemical oxygen demand (COD) was 1.25, the pH value was 3.5, the H2O2/Fe2 + molar ratio was 1:1, and the reaction time was 60 min. Under these conditions, the highest biochemical oxygen demand (BOD5)/COD value obtained was 0.74; the COD removal efficiency increased by 63.55%. And the output of iron sludge characterized by 30-min static sedimentation ratio was about 45.1%.

Paramecium spp. is types of free-living protists that live in freshwater environments. They are ciliates with high motility and phagocytosis and have been used to analyze cell motility and as a host model for pathogens. Besides such biological characteristics, apart from the usual morphological and genetic classification of species, the existence of taxonomies (such as syngens) and mating types related to Paramecium’s unique reproduction is known. In this study, we attempted to develop a simple method to identify Paramecium strains, which are difficult to distinguish morphologically, using random amplified polymorphic DNA (RAPD) analysis. Consequently, we can observe strain-specific band patterns. We also confirm that the presence of endosymbiotic Chlorella cells affects the band pattern of P. bursaria. Furthermore, the results of the RAPD analysis using several P. caudatum strains with different syngens show that it is possible to detect a band specific to a certain syngen. By improving the reaction conditions and random primers, based on the results of this study, RAPD analysis can be applied to the identification of Paramecium strains and their syngen confirmation tests.

The new type of four-component tandem Knoevenagel–Michael reaction was found: assembling arylaldehydes, N,N′-dimethylbarbituric acid, 4-hydroxycoumarine, and morpholine or piperidine has been successfully carried out in alcohols, other organic solvents and water at ambient temperature without catalyst or any other additives and resulted in the selective formation of the new substituted unsymmetrical scaffold with three different heterocyclic rings in 75–98% yields. The crystal structure of morpholin-4-ium 5-[(4-hydroxy-2-oxo-2H-chromen-3-yl)(phenyl)methyl]-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate and morpholin-4-ium 5-[(4-hydroxy-2-oxo-2H-chromen-3-yl)(4-nitrophenyl)methyl]-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate was confirmed by X-ray diffraction study. Thus, this new four-component tandem Knoevenagel–Michael strategy is a selective, facile, and efficient way to unsymmetrical scaffolds with three different pharmacology active heterocyclic rings. The optimized reaction conditions and a mechanistic rationale for this multicomponent assembling are presented.

In contrast to carbon-substituted isocyanates that are common building blocks, N-substituted isocyanates remain underdeveloped and reports on their N-acyl derivatives (i. e. amido-isocyanates) are exceedingly rare. Herein, amido-isocyanates were investigated in the context of syntheses of aza-tripeptide and hydantoins subunits starting from simple bench-stable precursors. A key finding is that the amido-isocyanate formed in situ cyclized to yield an oxadiazolone, and that under suitable reaction conditions this heterocycle is a traceless blocked (masked) N-isocyanate. Using organic bases as catalysts and upon heating, oxadiazolone formation is observed, and various nucleophiles to provide the desired aza-dipeptides or hydantoins in moderate to high yields. Further support for an amido-isocyanate intermediate was obtained using carboxylic acids as nucleophiles, affording N-acylhydrazide products.

Promoted by K2CO3 (2.0 equiv), the 1,3-dipolar [3+3] cy­cloaddition between 1, 4-benzodiazepinone-based nitrones and α-halohydroxamates processed smoothly under the mild reaction conditions and delivered structurally novel and complex cis- or trans-configured d-edge heterocycle-fused 1,4-benzodiazepinones in up to >99% isolated yield with >20:1 dr. The relative configuration of the title chemical entities was clearly identified with the use of single-crystal X-ray structure analysis. The reaction mechanism was assumed to interpret the diastereoselective production of the obtained cis- or trans-configured d-edge heterocycle-fused 1,4-benzodiazepinones.

An expedient three-component reaction for the synthesis of acenaphtho[1',2':4,5]pyrrolo[2,3-d]pyrimidine, (hydropyrimidinyl) acenaphtho[1',2':4,5]pyrrolo[2,3-d]pyrimidine, and phenanthro[9,10-b]pyrimido[4,5-e][1,4]oxazine is described. The desired products were obtained in good to high yields. This work has the advantages of convenient operation, mild reaction conditions, simple workup, and provides an entry point to fused heterocyclic structures.

A preparatively convenient and efficient synthetic route to new 5H-[1,3]thiazolo[3,2-c]pyrimidine derivatives is described which involves the cyclocondensation of acyl or alkoxycarbonyl α-functionalized 2-methylidene-1,3-thiazolidin-4-ones with 1-chlorobenzyl isocyanates. The optimal reaction conditions, viz., heating reagents in toluene in the absence of an organic base, afford the target products in 48–74% yields. Some tert-butyl 2-(4-oxo-1,3-thiazolidin-2-ylidene)ethanoates produce, along with the desired tert-butyl [1,3] thiazolo[3,2-c]pyrimidine-8-carboxylates, the corresponding 8-carboxylic acids in 18–21% yields. A reliable structural determination of all the synthesized compounds has been performed by elemental analysis and a number of spectroscopic methods (1H and 13C NMR, HPLC/MS, and FT-IR) as well as by X-ray diffraction analysis.

A novel method for the synthesis of 3-monohalooxindoles by acidolysis of isatin-derived 3-phosphate-substituted oxindoles with haloid acids was developed. This synthetic strategy involved the preparation of 3-phosphate-substituted oxindole intermediates and SN1 reactions with haloid acids. This new procedure features mild reaction conditions, simple operation, good yield, readily available and inexpensive starting materials, and gram-scalability.

Silver-catalyzed decarboxylative C–H alkylation of cyclic aldimines with abundant aliphatic carboxylic acids has been realized under mild reaction conditions generating the corresponding products in moderate to good yields (32%–91%). In addition, a gram-scale reaction, late-stage modification of drug, synthetic transformation of the product, and further application of the catalytic strategy were also performed. Preliminary studies indicate that the reaction undergoes a radical process.

Summary The catalytic hydrogenation of CO2 with renewable H2 is considered as one of the most practical approaches for the reduction of CO2 and the synthesis of valuable chemicals and fuels. Among the value-added products, olefins and aromatics are highly attractive as essential industrial feedstocks. CO2 hydrogenation to olefins and aromatics mainly undergoes a CO2-modified Fischer-Tropsch synthesis (CO2-FTS) route or a methanol-mediated (MeOH) route, but is often limited by low selectivity and catalyst deactivation. In this review, we first overview the reaction mechanisms and key intermediates along the CO2-FTS and MeOH routes. For each route, we summarize the recent progress toward the catalyst development as well as the optimization of reaction conditions. We conclude the review by identifying challenges and opportunities with an emphasis on approaches for exceeding the product distribution limit, suppressing the catalyst deactivation, and improving the feasibility of low-pressure operation by continuous consumption of key intermediates.

A new series of glycosyl benzofuranylthiazole derivatives were designed, synthesized, characterized, and evaluated as potential candidates to treat Alzheimer’s disease. The compounds have been synthesized by the cyclocondensation of glycosyl thiourea with a variety of 2-(bromoacetyl)benzofurans. The reaction conditions have been optimized, and good yields (79–95%) have been obtained. The synthesized compounds showed different degrees of cholinesterase inhibitory activity.

Macrocyclic lactones have redolent characteristics of muscones that originate from the rectal musk organs of the musk deer. These lactones are the primary raw material in the flavor and fragrance industry and are also found within the cyclic frameworks of various bioactive molecules. Due to great demand, many efforts have been made for their synthesis; however, strategies generating a large number of macrocyclic analogues from renewable resources have not been fully realized and are urgently required. Here, we outline a sustainable, straightforward, and eco-friendly approach to synthesize high-valued macrocyclic lactones utilizing olive oil under greener reaction conditions. The outlined method allows us to turn biomass into valuable 12- to 29-membered lactones and dilactones.

A new, simple, yet easily accessible, (1-selenocyanatoethyl)benzene has been designed and applied as a SeCN group transfer reagent for selenocyanation of aliphatic C(sp3)-H bonds for the first time. This protocol is featured with mild reaction conditions and wide substrate scope. Control experiments reveal that a radical-group transfer mechanism might be involved.

Data on the synthesis and structures of Zn(II) and Cd(II) complexes with boron cluster anions [BnHn]2– (n = 6, 10, 12), their substituted derivatives, as well as analogs—carboranes and metallaboranes—in the presence of competitive organic ligands are generalized and summarized. The synthesis and structural features of the obtained compounds, isomeric composition of the compounds, and influence of the reaction conditions on the composition and structures of the final products are discussed. A classification of compounds is given depending on the strength of the metal–boron cage interaction.

Polymer-silica hybrid support (SA-2-AMPS-SiO2) was synthesized and Co (II), Cu (II) metals were loaded over hybrid support by incipient impregnation technique. Oxidation of ethylbenzene was carried out for testing catalytic activity of catalysts at different reaction conditions i.e. the mole ratio of ethylbenzene to TBHP and reaction temperature. The main oxidation product was acetophenone along with benzaldehyde as the minor product and the highest ethylbenzene conversion (83.65 %) was attained at a 1:4 mol ratio of ethylbenzene to TBHP and temperature at 100 °C. The reusability of the catalysts was also determined and results showed that they can be easily reused three times without much loss in their structural and catalytic properties.

Using lignocellulosic char instead of the original biomass avoids the need for costly cleaning and conditioning stages of the producer gasification gas. However, lignocellulosic char gasification has been less extensively studied than gasification of lignocellulosic biomass, and a review of published works on this topic was missing. In this review the present status of char gasification technologies and their future prospects are critically discussed, including possible research opportunities. To date, most studies on char gasification have been performed in thermogravimetric analyzers (TGA) or TGA-like experimental setups. The major setback of TGA and TGA-like equipment is that they do not mimic the actual reaction conditions occurring in gasification reactors, which impedes a direct extrapolation of the findings during the scale-up of different gasification technologies. For this reason, in this literature review focus was put on studies undertaken in industrially relevant reactors, both in batch and continuous configurations. Overall, char gasification can be deemed a valid alternative for clean syngas production, contributing to an integral valorization of lignocellulosic residues within different biorefinery schemes. Of these, process intensification by microwave heating offers interesting opportunities for research and scaling-up, though efforts must be directed toward developing continuous microwave-assisted gasification processes.

White-rot fungi are thought to hold promise for development of a delignification pretreatment process for wood biorefinery that is less energy-consuming than current processes. However, the reaction must take place over weeks and consumes non-neglectable amounts of saccharides. To establish a biological process for wood biorefinery would first require establishment of an enzymatic approach to delignification. Such an approach has the potential to lower costs and reduce saccharide loss. Here, we attempted enzymatic delignification reactions using manganese peroxidases (MnP), a lignin-degrading enzyme, under several reaction conditions. The delignification rate from beech wood meal (particle size45 μm) of up to 11.0% in 48 h was reached in a MnP reaction supplemented with multiple co-oxidants, glucose, glucose oxidase (GOD) and commercial cellulase. An additional 48-h reaction using fresh MnP/co-oxidants increased the delignification rate to 14.2%. Simultaneous enzymatic delignification and saccharification, which occurs without a need for glucose supplementation, successfully improved the glucose yield to 160% of the reaction without MnP. Development of a more accurate imitation of the mechanisms of delignification that occurs in white-rot fungi has the potential to improve the monosaccharide yield resulting from simultaneous delignification and saccharification.

Catalytic C‒H functionalization has become a powerful strategy in organic synthesis due to the improved atom-, step- and resource economy in comparison with cross-coupling or classical organic functional group transformations. Despite the significant advances in the metal-catalyzed C‒H activations, recent developments in the field of metallaphotoredox catalysis enabled C‒H functionalizations with unique reaction pathways under mild reaction conditions. Given the relative earth-abundance and cost-effective nature, nickel catalysts for photoredox C‒H functionalization have received significant attention. In this review, we highlight the developments in the field of photoredox nickel-catalyzed C‒H functionalization reactions with a range of applications until summer 2021.

Cross-coupling reactions are essential for the synthesis of complex organic molecules. Here, we report a nickel-catalyzed Ullmann cross-coupling of two sp2-hybridized organohalides, featuring high cross-selectivity when the two coupling partners are used in a 1:1 ratio. The high chemoselectivity is governed by the bathocuproine ligand. Moreover, the mild reductive reaction conditions allow that a wide range of functional groups are compatible in this Ullmann cross-coupling.

A rare earth metal-catalyzed sequential inter- and intramolecular C-N bond formation of 2-nitrile-2'-alkenyl(alkynyl)biphenyls with amines has been developed, which provides a straightforward and efficient access to a range of new functional dibenzo[c,e]azepines. This represents the first examples of direct construction of seven-membered azaheterocycle from unsaturated nitriles and amines. Such transformations have the advantages of avoiding the use of additives, easily available starting materials, step- and high atom-economy, mild reaction conditions, and high selectivity.

CuH-catalyzed intramolecular cyclization and intermolecular allylation of benzimidazoles with allenes have been described. The reaction proceeded smoothly with the catalytic system of Cu(OAc)2/Xantphos and catalytic amount of (MeO)2MeSiH. This protocol features mild reaction conditions and a good tolerance of substrates bearing electron-withdrawing, electron-donating, or electron-neutral groups. A new catalytic mechanism was proposed for this copper hydride catalytic system.

A laboratory project to introduce upper-level undergraduates to Pd-catalyzed C–N σ-bond forming reactions is described. The exercise involves evaluation of monodentate phosphine ligands and solvents for the Buchwald–Hartwig coupling of 4-chloro- or 4-bromo-anisole with morpholine. Students gain experience in the synthesis of a biarylphosphine ligand, performing reactions under anhydrous and anaerobic conditions, with systematic screening and analysis of reaction conditions, and with the use of GC–MS data to gauge the extent of each coupling reaction. Students develop arguments from spectroscopic evidence to support claims regarding the effectiveness of each set of reaction conditions and explore the impact of the ligand within the context of currently accepted mechanistic models. Optimal conditions are determined and used for the scaled-up synthesis of the coupling product, and electronic aspects of the product are explored via computational chemistry.

To make crucial prevention, reduce fish losses and minimize the economic damage of diseases on the fish farm owners, a rapid detection of fish pathogens is mandatory. In this study, a loop-mediated isothermal amplification assay combined with hydroxynaphthol blue dye (LAMP-HNB) was developed and used for the rapid detection of Aeromonas salmonicida that caused significant economic losses in fish farming. Firstly, a pair of outer and inner primers specific for conserved fragment of vapA gene in A. salmonicida were designed and synthesized. Secondly, by optimizing the reaction conditions including reaction temperature, time, Mg2+ concentration, dNTP concentration and primer ratio, a LAMP-HNB assay was successfully established for the detection of A. salmoncida. Thirdly, the assay showed good specificity with no false-positive and false-negative results, and good sensitivity with the detection limit of 3.077 × 10-6 ng/μl, which was 102 times more sensitive than the conventional PCR. Finally, the LAMP-HNB assay was validated by the fish samples inoculated with different concentrations of A. salmoncida. This is the first development of rapid visual detection of A. salmonicida based on LAMP-HNB assay, which has great application prospect and market for diagnostic testing, health certification and active surveillance programmers.

A TBAI-mediated sulfenylation of N,3-diaryl-1-arylsulfonyl-1H-pyrazol-5-amines with arylsulfonyl hydrazides has been established, and an expanded inventory of N,5-diaryl-4-(arylthio)-1H-pyrazol-3-amines was constructed through C–S bond formation and N–S bond breaking. Mechanistic investigations suggest thiosulfonate as a key intermediate in the sulfenylation, and the detosylation is promoted by the generated arylsulfinic acid. The method is characterized by simple operating conditions, broad substrate range as well as gram-scale reaction.

A regioselective arylation of aliphatic N-fluorosulfonamides with imidazopyridines enabled by breaking of N-F and α C(sp3)-H bond to form C-N and C-C bonds was described. With CuCl as the catalyst, a radical mechanism was proposed to produce N-arylated aliphatic sulfonamides via a N radical intermediate. Importantly, under acidic conditions, an in situ generated imine was the possible intermediate, which was trapped by imidazopyridines to form α C(sp3)-H arylated aliphatic sulfonamides. The current protocol featured a broad substrate scope, tunable reaction conditions, operational convenience, and good regioselectivity.

A new alkylation reaction of monosubstituted tetrazoles via the diazotization of aliphatic amines is reported. This method enables preferential formation of 2,5-disubstituted tetrazoles. A one-pot 1,3-dipolar cycloaddition/diazotization sequence starting from widely available nitriles is also described. Azide residues are quenched in the second step with the nitrite reagent, thus limiting the intrinsic risk associated with trimethylsilyl azide. The reaction conditions were compatible with several functional groups, including thiocyanates, which afford preferentially disubstituted 2-alkyl-5-(substituted-thio)tetrazoles.

Tatter leaf disease caused by citrus tatter leaf virus (CTLV) is a serious threat to the citrus industry. In this study, a reverse transcription-droplet digital polymerase chain reaction (RT-ddPCR) assay for detection of CTLV was established by optimizing the reaction conditions. The dynamic range of the detection of CTLV RNA transcripts by RT-ddPCR was from 5 to 5 × 105 copies/μL, and the sensitivity was 10 times higher than that of RT real-time PCR. Both techniques showed a high degree of linearity and quantitative correlation. The number of positive samples that was identified in field citrus samples using RT-ddPCR (62.3%) was higher than that of RT-qPCR (49.2%). The results demonstrated that the RT-ddPCR assay is a promising tool for improving CTLV detection.

A novel approach to 2-substituted-2-(dimethoxyphosphoryl)-pyrrolidines 7a-7o and 9a-9r has been developed, which features a TMSOTf-mediated one-pot intramolecular cyclization and phosphonylation of substituted tert-butyl 4-oxobutylcarbamates. The major advantages of this method include simple operation under mild reaction conditions, the use of cheap Lewis acid, and good to excellent yields with high diastereoselectivities (dr up to 99:1).

A copper-catalyzed C-3 functionalization of imidazo[1,2-a]pyridines with 3-indoleacetic acids through an aerobic oxidative decarboxylative process has been developed. The protocol provided a series of 3-(1H-indol-3-ylmethyl)-imidazo[1,2-a]pyridines in moderate to good yields under simple reaction conditions. Importantly, some products exhibited potent antiproliferative activity in cancer cell lines.

ConspectusNatural products are constructed by organisms in impressive ways through various highly selective enzyme-catalyzed chemical reactions. Over the past century, there has been considerable interest in understanding and emulating the underlying biosynthetic logic for the target molecule. The successful implementation of a biomimetic strategy usually has some uniquely valuable benefits over other abiotic routes in total synthesis by (1) corroborating the chemical feasibility of a given biogenetic hypothesis and further unraveling some insightful implications for future biosynthetic studies and (2) providing remarkably more concise access to not only the original synthetic target but also diversified biogenetically related congeners, which may result in either the structural reassignment of previously disclosed natural products or the anticipation of undiscovered natural products. However, for the devised essential biomimetic transformation, fine-tuning the optimization of the substrates and the reaction conditions can sometimes be painstakingly challenging. Turning to nature for inspiration can provide additional impetus for methodological innovations.Previously used as oral veterinary drugs, lankacidins have potential as next-generation antibiotics to tackle the problems caused by multidrug-resistant bacteria with novel modes of action (MoAs). The hypersensitive and densely functionalized lactonic core within this family of macrocyclic polyketides poses a formidable challenge for chemical total synthesis and derivatization. In this account, we summarized the evolution of a unified biomimetic approach toward 10 lankacidin antibiotics and their linear biosynthetic intermediates in the longest linear 7-12 steps from readily available starting materials. Our endeavor commenced with an intermolecular bioinspired amido sulfone-based Mannich reaction approach to assemble 2 advanced fragments under mild biphasic organocatalytic conditions. It successfully gave rise to stereodivergent access to 4 C2/C18-isomeric lankacyclinols but failed to efficiently deliver lactone-containing congeners through Stille macrocyclization. Facilitated by the thermolysis chemistry of N,O-acetal to generate the requisite N-acyl-1-azahexatriene species, we realized the projected Mannich macrocyclization and eight macrocyclic lankacidins can be produced by orchestrated desilylative manipulations. In this process, we were able to perform structural reassignments of isolankacidinol (7 to 50) and isolankacyclinol (104 to 83) and, for the first time, elucidate the natural occurrence of 2,18-bis-epi-lankacyclinol (84). Moreover, the inability of the current biomimetic route to cofurnish the reported structure of 2,18-seco-lankacidinol A (15) triggered a proposed structural revision that is rooted in reconsidered biogenesis and was confirmed by a divergent synthesis that enabled us to identify the correct isomer (116). Finally, the modular, diversity-oriented design also provided streamlined entries to acyclic 2,18-seco-lankacidinol B (120) and the biosynthetic intermediate LC-KA05 (17) together with its C7-O-deacetylated congeners in all C4/C5-stereochemical variations (18, 127-129), culminating in a need for structural revision to the six-membered lactonic segment in LC-KA05-2. The selection and execution of biomimetic strategies in lankacidin total synthesis give rise to all the previously mentioned advantages at the current stage. The modular-based, late-stage diversified complex construction offers an exceptionally high level of synthetic flexibility for future synthetic forays toward newly isolated or chemically modified congeners within the lankacidin family.

The reaction of o-benzofulvene with TfOH leads to intramolecular cyclization through novel C-C and C-N bond formation, resulting in the formation of 5H,10'H-spiro[benzo[k]phenanthridine-5,6'-dibenzopentalene]. This protocol provides a new molecular framework with reasonable to excellent yields and tolerates various electron-withdrawing/donating substituents. This method yields diastereoselectivity of up to >20:1. Furthermore, it is free of bases, oxidants, and metals and proceeds under mild reaction conditions, which are favorable for synthetic organic chemistry.

Cyanosilylation of carbonyl compounds provides protected cyanohydrins, which can be converted into many kinds of compounds such as amino alcohols, amides, esters, and carboxylic acids. In particular, the use of trimethylsilyl cyanide as the sole carbon source can avoid the need for more toxic inorganic cyanides. In this paper, we describe an electrochemically initiated cyanosilylation of carbonyl compounds and its application to a microflow reactor. Furthermore, to identify suitable reaction conditions, which reflect considerations beyond simply a high yield, we demonstrate machine learning-assisted optimization. Machine learning can be used to adjust the current and flow rate at the same time and identify the conditions needed to achieve the best productivity.