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Phenol trifluoromesylates were utilized as substrates to synthesize aromatic tertiary amines in moderate to excellent yields through a Catellani-type pathway.

A palladium-catalysed C–C bond-forming reaction via deaminative and decarboxylative cross-coupling of organoammonium salts with a series of carboxylic acids (including polyfluoroaromatic, propiolic and α-cyano benzyl carboxylic acids) was developed.

A base-promoted direct deaminative olefination of organoammonium salts was developed.

Direct phosphorylation of benzylic C–H bonds with secondary phosphine oxides was first realized. The reaction was performed in organo/aqueous biphasic system and under transition metal-free conditions, proceeding via the cross dehydrogenative coupling.

A facile and versatile method for generating radicals from Csp3-H bonds under metal-free and organic-peroxide-free conditions was developed. By combining safe persulfate and low-toxic quaternary ammonium salt, a wide variety of Csp3-H compounds including ethers, (hetero)aromatic/aliphatic ketones, alkylbenzenes, alkylheterocycles, cycloalkanes, and haloalkanes were selectively activated to generate the corresponding C-centered radicals, which could be further captured by N-arylacrylamides to deliver the valuable functionalized oxindoles. Good functional group tolerance was demonstrated. The useful polycarbonyl compound and esters were also modified with the strategy. Moreover, the combination can also be applied to the practical coupling between simple haloalkanes and N-hydroxyphthalimide (NHPI).

A palladium-catalyzed difunctionalization of bicyclic alkenes with organoammonium salts and organoboronic compounds was reported. A wide range of functionalized cyclic products, including those bearing functional groups, were produced stereoselectively in good to excellent yields. The gram-scale experiment, one-pot operation, and synthetic application of β-borylated products further demonstrated the synthetic value of this new reaction in organic synthesis.

The direct decarbonylative cyanation of benzoic acids with TMSCN was achieved through palladium catalysis. By this strategy, a wide range of nitriles including those with functional groups was synthesized in good to high yields. Moreover, this reaction applied to modifying bioactive molecules such as adapalene, probenecid, telmisartan, and 3-methylflavone-8-carboxylic acid. These results demonstrate that this new reaction has potential synthetic value in organic synthesis.

A nickel-catalyzed decarbonylative thioetherification of carboxylic acids with thiols was developed. Under the reaction conditions, benzoic acids, cinnamic acids, and benzyl carboxylic acids coupled with various thiols including both aromatic and aliphatic ones produce the corresponding thioethers in up to 99% yields. Moreover, this reaction was applicable to the modification of bioactive molecules such as 3-methylflavone-8-carboxylic acid, probenecid, and flufenamic acid, and the synthesis of acaricide chlorbenside. These results well demonstrated the potential synthetic value of this new reaction in organic synthesis.

A base-promoted direct deaminative olefination of organoammonium salts was developed. Only mediated by KO

Direct phosphorylation of benzylic C-H bonds was achieved in a biphasic system under transition metal-free conditions. A selective radical/radical sp

A direct decarbonylative Sonogashira coupling of terminal alkynes with carboxylic acids was achieved through palladium catalysis. This reaction did not use overstoichiometric oxidants, thus overcoming the homocoupling issue of terminal alkynes. Under the reaction conditions, a wide range of carboxylic acids including those bioactive ones could couple readily with various terminal alkynes, thus providing a relative general method for preparing internal alkynes.

A facile and general method for constructing carbon-heteroatom (C-P, C-O, C-S, and C-N) bonds via C-N cleavage of benzyl ammonium salts under transition-metal-free conditions was reported. The combination of t-BuOK and 18-crown-6 enabled a wide range of substituted benzyl ammonium salts to couple readily with different kinds of heteroatom nucleophiles, i.e. hydrogen phosphoryl compounds, alcohols, thiols, and amines. Good functional group tolerance was demonstrated. The scale-up reaction and one-pot synthesis were also successfully performed.

A PIDA mediated intramolecular oxidative C–N coupling and subsequent detosylative aromatization to afford indolo[2,3-b]quinoline derivatives has been developed. This tandem reaction provided an efficient method for the synthesis of valuable indolo[2,3-b]quinoline derivatives.

The first visible light-induced dioxygenation of α,β-unsaturated amides with N-hydroxy compounds under air was developed with the use of the non-toxic organic dye rose bengal as the photoredox catalyst. This metal-free reaction is highly chemoselective, producing the corresponding β-oxy alcohols rather than the competitive cyclized products through aminooxyarylation. Other aromatic alkenes, dihydrofurans and dienes, were also applicable to this reaction. Compared with the established radical dioxygenation methods to construct β-oxy alcohols, the present photochemical protocol avoids the use of (over)stoichiometric amounts of hazardous/poisonous oxidants, transition metals and additional reducing reagents, yielding the desired dioxygenated products in a safe and eco-friendly fashion. Moreover, the practical application of this methodology is highlighted by a concise two-step synthesis of 1,4-dioxane-2-carboxamides, a framework for building Mcl-1 inhibitors.

The direct C–H arylation and acylation of azoles with carboxylic acids were achieved through Pd/Cu cooperative catalysis. Various biaryls and biaryl ketones were selectively produced in good to high yields from the same substrates. The key factor of high chemoselectivity was the choice of a suitable phosphine ligand: biaryls were generated selectively with dppp as the ligand, while biaryl ketones were obtained with high selectivity using dpph or Ph2PCy as the ligand.

A transition-metal-free and base promoted C-C bond forming reaction of benzyl C(sp3)-H bond with organoammonium salts via C-N bond cleavage has been reported. Benzyl ammonium salts as well as cinnamyl ammonium salt could couple readily with various benzyl C(sp3)-H species, producing the corresponding products in moderate to excellent yields with good functional group tolerance. Late stage chemical manipulation enabled the specific 1,2-diarylethane structure of products transformed into useful olefin compounds via dehydrogenation, which further demonstrated the utility of this reaction.

We have developed a protocol for efficient synthesis of N-aryl-substituted azacycles from aryl amines and cyclic ethers using I2/NaH2PO2 as the mediator. A diverse range of aryl amines and cyclic ethers undergo amination reaction to generate products in good to excellent yields with good functional group tolerance. This reaction can be easily scaled up to give N-aryl-substituted azacycles on a gram scale. Further chemical manipulation of the products enabled useful transformations of the quinoline ring, including bromination and acetylation.

The challenging transamidation of unactivated tertiary amides has been accomplished via cooperative acid/iodide catalysis. Most crucially, the method provides a novel manifold to re-route the reactivity of unactivated N,N-dialkyl amides through reactive acyl iodide intermediates, thus reverting the classical order of reactivity of carboxylic acid derivatives. This method provides a direct route to amide-to-amide bond interconversion with excellent chemoselectivity using equivalent amounts of amines. The combination of acid and iodide has been identified as the essential factor to activate the amide C-N bond through electrophilic catalytic activation, enabling the production of new desired transamidated products with wide substrate scope of both unactivated amides and amines, including late-stage functionalization of complex APIs (80 examples). We anticipate that this powerful activation mode of unactivated amide bonds will find broad-ranging applications in chemical synthesis.

Herein, we highlight advances in the phosphorylation of readily available carboxylic acids and their derivatives forming synthetically important P(O)–sp3C, P(O)–sp2C, and P(O)–spC bonds, with an emphasis on the results demonstrated since 2010. This review examines the challenges associated with the use of this strategy for the synthesis of organophosphorus compounds and details advances in the design of catalytic systems that suppress these problems thus resulting in notable progress. Mechanistic details are discussed where available.1 Introduction2 Formation of P(O)–sp3C Bonds3 Formation of P(O)–sp2C Bonds4 Formation of P(O)–spC Bonds5 Outlook and Conclusion

Alkynes are among the most fundamentally important organic compounds and are widely used in synthetic chemistry, biochemistry, and materials science. Thus, the development of an efficient and sustainable method for the preparation of alkynes has been a central concern in organic synthesis. Cross-dehydrogenative coupling utilizing E-H and Z-H bonds in two different molecules can avoid the need for prefunctionalization of starting materials and has become one of the most straightforward methods for the construction of E-Z chemical bonds. This Review summarizes recent progress in the preparation of internal alkynes by cross-dehydrogenative coupling with terminal alkynes.

A palladium-catalyzed cyclobutanation of aryl sulfonates with strained alkenes has been developed. The methodology is featured to achieve the cleavage of both C–O and C–H bonds of phenol derivative...

Contemporary ocean colour radiometers and inversion algorithms to derive optical properties and oceanic constituents rely only on the scalar treatment of water-leaving radiance (Lw). However, Lw po...

Hydroxyl-containing compounds are highly value-added organic molecules, and the establishment of novel methodologies for their elaboration is a long-standing challenge in organic synthesis. Here the first oxone-mediated direct arylhydroxylation of activated alkenes was developed for the synthesis of valuable hydroxyl-containing oxindoles and 3,4-dihydroquinolin-2-ones. The products were controlled by adjusting the structure of the starting alkenes. Moreover, the reaction was performed under simple conditions without any external additives or catalysts. Primary mechanistic studies showed that this reaction was a tandem process involving epoxidation and subsequent Friedel–Crafts alkylation, and oxone played a dual role (both the oxidant and proton source) in this process.

A transition metal-free α,β-dehydrogenation of ketones and aldehydes was developed. This reaction was conducted in a facile I2/KI/DMSO system to produce the corresponding unsaturated compounds in good to high yields. The gram-scale experiment also indicated the potential synthetic value of this new reaction in organic synthesis. In the reaction, DMSO acted as both solvent and mild oxidant.

Developing an efficient and quality remote sensing (RS) technology using volume and efficient modelling in different aircraft RS images is challenging. Generative models serve as a natural and convenient simulation method. Because aircraft types belong to the fine class under the rough class, the issue of feature entanglement may occur while modelling multiple aircraft classes. Our solution to this issue was a novel first-generation realistic aircraft type simulation system (ATSS-1) based on the RS images. It realised fine modelling of the seven aircraft types based on a real scene by establishing an adaptive weighted conditional attention generative adversarial network and joint geospatial embedding (GE) network. An adaptive weighted conditional batch normalisation attention block solved the subclass entanglement by reassigning the intra-class-wise characteristic responses. Subsequently, an asymmetric residual self-attention module was developed by establishing a remote region asymmetric relationship for mining the finer potential spatial representation. The mapping relationship between the input RS scene and the potential space of the generated samples was explored through the GE network construction that used the selected prior distribution z, as an intermediate representation. A public RS dataset (OPT-Aircraft_V1.0) and two public datasets (MNIST and Fashion-MNIST) were used for simulation model testing. The results demonstrated the effectiveness of ATSS-1, promoting further development of realistic automatic RS simulation.

The unmanned aerial vehicle (UAV)-borne hyperspectral imaging system has the advantages of high spatial resolution, flexible operation, under-cloud flying, and easy cooperation with ground synchronous tests. Because this platform often flies under clouds, variations in solar illumination lead to irradiance inconsistency between different rows of hyperspectral images (HSIs). This inconsistency causes errors in radiation correction. In addition, due to the accuracy limitations of the GPS/inertial measurement unit (IMU) and irregular changes in flight platform speed and attitude, HSIs have deformation and drift, which is harmful to the geometric correction and stitching accuracy between flight strips. Consequently, radiation and geometric error limit further applications of large-scale hyperspectral data. To address the above problems, we proposed an integrated solution to acquire and correct UAV-borne hyperspectral images that consist of illumination data acquisition, radiance and geometric correction, HSI, multispectral image (MSI) registration, and multi-strip stitching. We presented an improved three-parameter empirical model based on the illumination correction factor, and it showed that the accuracy of radiation correction considering illumination variation improved, especially in some low signal-to-noise ratio (SNR) bands. In addition, the error of large-scale HSI stitching was controlled within one pixel.

A facile and versatile method for generating radicals from Csp

A transition-metal-free and base promoted C-C bond forming reaction of benzyl C(sp

The trifluoromethylation of benzoic acids with TMSCF3 was achieved through nucleophilic substitution with the use of anhydrides as an in situ activating reagent. Under the reaction conditions, a wide range of carboxylic acids including the bioactive ones worked well, thus providing a facile and efficient method for preparing aryl trifluoromethyl ketones from the readily available starting materials.

The polarization properties of water-leaving radiance (Lw) contains rich information about hydrosols, which has great potential to improve the retrieval accuracy of oceanic constituents. However, c...

A base-initiated thioesterification of amides with various thiols is reported. This reaction can take place efficiently under metal-free and air-atmospheric conditions, and provides a facile and practically useful approach to the synthesis of valuable acyl thioesters.

A practical and sustainable synthesis of arylsulfonate esters has been developed through electro-oxidation. This reaction employed the stable and readily available phenols and sodium arenesulfinates as the starting materials and took place under mild reaction conditions without additional oxidants. A wide range of arylsulfonate esters including those bearing functional groups were produced in good to excellent yields. This reaction could also be conducted at a gram scale without a decrease of reaction efficiency. Those results well demonstrated the potential synthetic value of this reaction in organic synthesis.

A PIDA mediated intramolecular oxidative C-N coupling and subsequent detosylative aromatization to afford indolo[2,3

Fourier transform imaging spectrometers (FTISs) are widely used in global hyperspectral remote sensing due to the advantages of high stability, high throughput, and high spectral resolution. Spectrum reconstruction (SpecR) is a classic problem of FTISs determining the acquired data quality and application potential. However, the state-of-the-art SpecR algorithms were restricted by the length of maximum optical path difference (MOPD) of FTISs and apodization processing, resulting in a decrease in spectral resolution; thus, the applications of FTISs were limited. In this study, a deep learning SpecR method, which directly learned an end-to-end mapping between the interference/spectrum information with limited MOPD and without apodization processing, was proposed. The mapping was represented as a fully connected U-Net (FCUN) that takes the interference fringes as the input and outputs the highly precise spectral curves. We trained the proposed FCUN model using the real spectra and simulated pulse spectra, as well as the corresponding simulated interference curves, and achieved good results. Additionally, the performance of the proposed FCUN on real interference and spectral datasets was explored. The FCUN could obtain similar spectral values compared with the state-of-the-art fast Fourier transform (FFT)-based method with only 150 and 200 points in the interferograms. The proposed method could be able to enhance the resolution of the reconstructed spectra in the case of insufficient MOPD. Moreover, the FCUN performed well in visual quality using noisy interferograms and gained nearly 70% to 80% relative improvement over FFT for the coefficient of mean relative error (MRE). All the results based on simulated and real satellite datasets showed that the reconstructed spectra of the FCUN were more consistent with the ideal spectrum compared with that of the traditional method, with higher PSNR and lower values of spectral angle (SA) and relative spectral quadratic error (RQE).

The controllable phosphorylations of thioesters were developed. When the reaction was catalyzed by a palladium catalyst, aryl or alkenyl phosphoryl compounds were generated through decarbonylative coupling, while the benzyl phosphoryl compounds were produced through deoxygenative coupling when the reaction was carried out in the presence of only a base.

A palladium-catalyzed decarbonylative alkenylation of aromatic carboxylic acids was developed. Under the reaction conditions, various benzoic acids including those bearing functional groups coupled to terminal alkenes, producing the corresponding internal alkenes in good to high yields. Cinnamic acids and bioactive benzoic acids such as 3-methylflavone-8-carboxylic acid, probenecid, adapalin, and febuxostat were also applicable to this reaction, demonstrating the potential synthetic value of this new reaction in organic synthesis.

A palladium-catalyzed N-acylation of tertiary amines by carboxylic acids was achieved through C-N cleavage. This reaction showed a wide substrate scope. Both aromatic and aliphatic acids served well as the acylating reagents and coupled with tertiary amines to produce the corresponding amides in good to excellent yields. With the strategy, bioactive carboxylic acids were also efficiently modified, highlighting the synthetic value of the process in organic synthesis.

A direct phosphorylation of the sp3C-CN bond catalyzed by a nickel catalyst is disclosed. A wide range of primary nitriles readily coupled with secondary phosphine oxides to produce the corresponding phosphorylated products in high yields. As a key step, this new method was applied to the synthesis of anticancer drug Combretastatin-A4, significantly shortening its synthetic path.

Affected by the sensor itself, illumination, atmosphere, terrain and other factors, even if imaging the same region at the same time, the spectral characteristics of ground objects in different remote sensing images are also very different, and the surface parameters, ground object classification and target recognition results of the inversion are also different, which brings great uncertainty to quantitative analysis. The relative radiation correction effect of PIF, method is obvious and the operation is simple, and the accuracy of the effect depends greatly on the selection of the PIF point. The general relative radiometric correction methods are linearization correction without considering the nonlinear difference of multi-temporal images. At present, most radiation normalization methods assume that the transformation relation between images is linear, extract PIF points and establish radiation transformation model. In this paper, Kernel Canonical Correlation Analysis (KCCA) is used for the first time to normalize the radiation between multi-temporal hyperspectral images, which can greatly reduce the nonlinear difference in relative radiation correction. Based on the theory of nuclear canonical correlation analysis, the radiation normalization method of multi-temporal aerial hyperspectral images is proposed. The feature points of PIF are extracted in the nuclear projection space, and the nonlinear model is used for the radiation normalization of hyperspectral images, to improve the radiation normalization accuracy of multi-temporal hyperspectral images. Compared with Canonical Correlation Analysis (CCA), the number and precision of PIF point extraction can be significantly improved. This method can satisfy the radiation normalization between aerial hyperspectral multi-temporal images.

Three-component reactions can directly convert three reactants into the desired products in one pot and thus greatly shorten the synthetic path. Recently, transition-metal catalysis has been applied in the difunctionalization of alkenes and remarkable progress has been achieved to facilitate the construction of a wide range of functional molecules with high atom- and step-economic efficiency. This Focus Review highlights recent advances in this field.

We carried out a comprehensive study on the generality, scope, limitations, and mechanism of the palladium-catalyzed hydrophosphorylation of alkynes with P(O)-H compounds (i.e., H-phosphonates, H-phosphinates, secondary phosphine oxides, and hypophosphinic acid). For H-phosphonates, Pd/dppp was the best catalyst. Both aromatic and aliphatic alkynes, with a variety of functional groups, were applicable to produce the Markovnikov adducts in high yields with high regioselectivity. Aromatic alkynes showed higher reactivity than aliphatic alkynes. Terminal alkynes reacted faster than internal alkynes. Sterically crowded H-phosphonates disfavored the addition. For H-phosphinates and secondary phosphine oxides, Pd/dppe/Ph2P(O)OH was the catalyst of choice, which led to highly regioselective formation of the Markovnikov adducts. By using Pd(PPh3)4 as the catalyst, hypophosphinic acid added to terminal alkynes to give the corresponding Markovnikov adducts. Phosphinic acids, phosphonic acid, and its monoester were not applicable to this palladium-catalyzed hydrophosphorylation. Mechanistic studies showed that, with a terminal alkyne, (RO)2P(O)H reacted, like a Bronsted acid, to selectively generate the α-alkenylpalladium intermediate via hydropalladation. On the other hand, Ph(RO)P(O)H and Ph2P(O)H gave a mixture of α- and β-alkenylpalladium complexes. In the presence of Ph2P(O)OH, hydropalladation with this acid took place first to selectively generate the α-alkenylpalladium intermediate. A subsequent ligand exchange with a P(O)H compound gave the phosphorylpalladium intermediate which produced the Markovnikov adduct via reductive elimination. Related intermediates in the catalytic cycle were isolated and characterized.

An efficient oxidative aminooxyarylation of alkenes under a transition-metal-free condition was described. Under the reaction conditions, N-hydroxyphthalimide (NHPI) reacted readily with N-arylacrylamides to produce cyclic products via a radical C–H functionalization process, achieving both C–O and C–C bonds formation in one pot. This reaction provided a facile access to the valuable aminooxylated oxindoles. The benzylic and α-methylene C(sp3)-H bonds were also aminooxylated under the reaction conditions.