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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.

An efficient iodocarbocyclization of alkenes for the synthesis of iodooxindoles has been developed. This reaction proceeds in a chemoselective manner and shows excellent tolerance of various functional groups, including a chemosensitive hydroxymethyl group. Nonmetal inorganic iodine pentoxide was used as both the oxidant and iodine source, making this protocol very practical. On the basis of experimental observations, a plausible electrophilic reaction mechanism was proposed.

A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.

A t-BuONa-mediated C-OH/P(O)-H cross dehydration coupling to produce alkylphosphine oxides is developed. This reaction employed readily available alcohols and P(O)-H compounds as the starting materials, providing an efficient alternative method for constructing sp3 C-P bonds. A reasonable reaction path involving dehydration and subsequent regio-selective hydrophosphorylation of the resulting alkenes was proposed.

Trimethyl phosphine was used as an efficient catalyst for the addition of P(O)-H compounds to electron-deficient alkenes. The addition reactions were generally conducted using a catalytic amount of Me3P under mild reaction conditions. Both 1 to 1 and 1 to 2 adducts were obtained.

Alkynes are important raw materials for the generation of a variety of useful organic compounds through the construction of new C C, C H or C X bonds. Although relatively low in thermodynamic reactivity, alkynes can be readily and selectively activated in the presence of functional groups under mild conditions. The activation is done by means of metal or metal-free catalysis through either selective alkyne C C bond or terminal alkyne C H bond reactions. From the standpoint of green chemistry, it is desirable to develop catalytic processes for the transformation of alkynes that have the least impact on our environment. In this mini-review, we summarize the progresses of alkyne transformation to functional substances in the past six years, with emphasis on the results generated in our research group: heterocoupling of terminal alkynes into unsymmetrical 1,3-diynes, selective hydrogenation of alkynes with formic acid or hypophosphorous acid, and functionalization of alkynes by O-, P-, or S-containing molecules. The advantages and disadvantages of these processes and the effects of reaction conditions are systematically described. Moreover, the catalysts adopted for these processes are illustrated and compared. Finally, we make a prediction on the processes that have potential for industrial applications in the near future.

An air-induced double addition of diphenyl phosphine oxide to various alkynes is reported. This reaction can proceed efficiently under metal- and solvent-free conditions, and is a clean and practically useful method for the preparation of the valuable 1,2-bisphosphorylethanes.

A coupling of multiple C(sp3)–H bonds of the methyl group in methyl ketones with dimethyl sulfoxide is developed. This coupling allows the direct C(sp3)–H bond coupling among three methyl groups and affords one C–C bond and one CC bond under transition metal-free conditions. The value-added cyclized 3-methylthiomethyl chroman-4-ones can be synthesized through this method. A plausible mechanism is proposed.

A metal-free and radical-free synthesis of heteroaromatic aldehydes was developed through aerobic oxidation of methyl groups in an I2/DMSO/O2 catalytic system. Under the reaction conditions, various functional groups such as methoxy, aldehyde, ester, nitro, amide, and halo (F, Cl, Br) groups were well tolerated. The bioactive compounds like chlorchinaldin derivative and papaverine were also oxidized to the corresponding aldehydes and ketones. This reaction provided an efficient method for preparing the valuable heteroaromatic aldehydes.

Most scene text detection methods based on deep learning are difficult to locate texts with multi-scale shapes. The challenges of scale robust text detection lie in two aspects: 1) scene text can be diverse and usually exists in various colors, fonts, orientations, languages, and scales in natural images. 2) Most existing detectors are difficult to locate text with large scale change. We propose a new Inception-Text module and adaptive scale scaling test mechanism for multi-oriented scene text detection. the proposed algorithm enhances performance significantly, while adding little computation. The proposed method can flexibly detect text in various scales, including horizontal, oriented and curved text. The proposed algorithm is evaluated on three recent standard public benchmarks, and show that our proposed method achieves the state-of-the-art performance on several benchmarks. Specifically, it achieves an F-measure of 93.3% on ICDAR2013, 90.47% on ICDAR2015 and 76.08%1 on ICDAR2017 MLT.

A nickel-catalyzed phosphorylation of aryl triflates with P(O) H compounds is disclosed. This reaction can proceed smoothly under a mild reaction condition, producing the corresponding aryl phosphorus compounds in good to high yields.

Optically active α-hydroxyphosphinates with both C- and P-stereogenic centers are obtained by rhodium- or iridium-catalyzed substrate-directed stereoselective addition of the optically pure H-phosphinates to aldehydes. The reaction most probably proceeds by a transition-metal-catalyzed mechanism with hydridometal complexes as key intermediates in the catalytic cycle.

Efficient Ni-catalyzed direct cross-couplings of benzylic alcohol derivatives with arylacetonitriles via CO activation are described. Various α-benzylated arylacetonitriles including those with functional groups can be prepared under mild reaction conditions.

The direct oxidative acylation of phenols with N-heteroarylmethanes via sp3C–H and sp2C–H double activation was achieved under transition metal-free reaction conditions. This transformation proceeds in a facile I2/DMSO/O2 system regio-selectively to produce valuable (2-hydroxyphenyl)arylmethanones from easily available starting materials in moderate to good yields. A plausible mechanism was proposed.

The nickel-catalyzed α-benzylation of sulfones with readily available benzylic alcohol derivatives was achieved via C–O activation. The transformation was complete in 30 minutes using a simple Ni(COD)2 as a catalyst without any additional ligands. A variety of substituted sulfones including the building block for bioactive compound eletriptan were synthesized by using the strategy.

An efficient Ni-catalyzed synthesis of (E)-olefins using the readily available benzylic alcohol derivatives and arylacetonitriles is described. This transformation should proceed via a tandem process involving nickel-catalyzed cross coupling via C–O activation and subsequent stereoselective E2 elimination.

Efficient copper-catalysed aerobic oxidative esterification of N-heteroaryl methanes with alcohols has been developed. A variety of N-heteroaryl esters including those with functional groups are produced in good to excellent yields under the present reaction conditions.

Because of the unique properties and wide applications, continuing efforts have been devoted to developing simpler and cleaner methods for the synthesis of organophosphorus compounds. Recently, transition metal-catalysed dehydrogenative coupling has been emerging as one of the powerful methodologies for constructing chemical bonds. Herein, we highlight the recent progress in the preparation of organophosphorus compounds via transition metal-catalysed dehydrogenative couplings of P(O)H compounds with Z-H compounds.

An efficient oxygen-phosphoryl bond-forming reaction via iron-catalyzed cross dehydrogenative coupling has been developed. This transformation proceeds efficiently under oxidant- and halide-free reaction conditions with H2 liberation, and represents a straightforward method to prepare valuable organophosphoryl compounds from the readily available alcohols and P(O)-H compounds.

The first nickel-catalyzed phosphinylation of C–S bonds forming C–P bonds is developed. The reaction can proceed readily with the simple Ni(cod)2 at a loading down to 0.1 mol% at the 10 mmol scale. Various aryl sulfur compounds, i.e. sulfides, sulfoxides and sulfones all couple with P(O)–H compounds to produce the corresponding organophosphorus compounds, which provides an efficient new method for the construction of C–P bonds.

A simple and environmentally benign method was developed for the synthesis of chalcones in high to excellent yields by a phosphorous acid promoted alkyne–aldehyde hydration–condensation in an oil/water two-phase system. The method is the first efficient protocol for the preparation of chalcones that is mediated by a simple Bronsted acid in a two-phase system.

An efficient and highly stereoselective reduction of a gem-dibromocyclopropane to the corresponding monobromocyclopropane under mild reaction conditions was developed using a combination of dimethy...

A palladium-catalyzed alkynylation of aromatic amines with terminal alkynes via in situ formed trimethylammonium salts is developed. Compared with previous system using ammonium salts as starting materials and high loading of pre-prepared NHC-Pd catalyst (10 mol% Pd), this reaction directly employed amines as the coupling partners and the commercially available Pd2(dba)3/PPh2Cy (1 mol% Pd) as the catalyst, greatly simplifying the manipulation and decreasing the cost.

A palladium-catalyzed phosphorylation of benzyl ammonium triflates with P(O)H compounds has been developed. Various benzylphosphorus compounds were produced in good to excellent yields with high functional group tolerance. All the three kinds of hydrogen phosphoryl compounds, i.e. H-phosphonates, H-phosphinates and secondary phosphine oxides, were applicable to this reaction. The successful scale-up experiment and one-pot synthetic operation also well demonstrated its practicality.

A direct phosphorylation of the sp

The polarization of water-leaving radiance (Lw) is more sensitive to microphysical properties (e.g. particles shapes, size distributions, compositions, and refractive index) of hydrosols than the unpolarised radiance. Hence, the polarized Lw can be used to extract additional information on oceanic constituents, which is complementary to the spectral and angular radiance measurements. In this study, the polarization characteristics of underwater upwelling radiance in turbid waters with respect to suspended particulate matters have been investigated. The full Stokes components of the underwater upwelling radiance in the visible spectrum are calculated using a radiative transfer model. And then, the influences of suspended particulate matter concentrations on the directional variations and the polarization of underwater upwelling radiance are examined. The results reveal that the polarization of underwater upwelling radiance (I, Q, U, DOP) shows significant multidirectional variations with respect to observation geometries, wavelengths, and solar zenith angles. Moreover, the polarization of underwater upwelling radiance is highly related to the suspended particulate matter concentrations. It demonstrates the potential of using the polarized signal to retrieve particle concentrations in coastal waters. Therefore, the development of in-situ instrumentations and next generation of ocean color sensors should able to measure the polarization properties of water-leaving radiance are recommended.

The inversion of total suspended particulate matter (TSM) from ocean color remote sensing data in coastal waters is still highly inaccurate due to contributions of various oceanic constituents and non-linear independently variation of each other. Since the absorption and scattering by molecules, aerosols, and hydrosols and reflection, transmission over the sea surface, the initially completely unpolarized sunlight becomes partially polarized after transmitting in the coupled atmosphere-ocean system (AOS). Hence, the polarization of the sunlight, which contains embedded information on atmospheric and water optical properties, has largely been neglected. In addition, the parallel polarization radiance (PPR) has two significant advantages in effectively diminishing the sun-glint contamination and enhancing the ocean color signal at the top-of-atmosphere (TOA). In this study, the directional variations in parallel polarized water-leaving radiance of suspended particulate matters in coastal waters, based on the vector radiative transfer simulations (RT), were examined. The simulations reveal that the traditional radiation intensity (I) and parallel polarization radiance (PPR) display significant multidirectional and spectral variations with respect to the observation geometries, and TSM concentrations. Moreover, the water-leaving (Lw) radiance for I and PPR have the same angular distribution pattern and magnitude under different bands. In addition, the relative fraction of Lw to Lt for PPR is large than I, indicating that the PPR can improve to retrieve the Lw radiance at the TOA. Furthermore, an exponent relationship between the Rrs_p and the TSM concentration has been established with low corresponding AD (1.258%) and RMSE (0.202). It demonstrates that the polarization of the Lw radiance is closely related to oceanic constituents, and has great potential for the retrieval of TSM concentrations.

Remote sensing images often suffer low contrast, and the efficiency and robustness of contrast enhancement for remote sensing images is still a challenge. To meet with the requirements of applications, Liu et al recently proposed a self-adaptive contrast enhancement method (HCTLS) based on the histogram compacting transform (HCT). In this method, some gray levels on which the frequency is smaller than a certain reference, will merged into their adjacent levels for a compact level distribution. However, if the merged levels whose corresponding pixels in some connected regions, local contrast of these connected regions will decrease, even disappear. In this paper, an improved enhancement method (DPHCT) for remote sensing image based on the HCTLS is presented for preserving more the local detail and contrast. Firstly, extracting the connected regions from the enhanced result by HCT where the local contrast is decreased or disappeared. These connected regions are decomposed into the inner regions and the boundary regions adaptively. Then, construct pixel values by using the unified brightness function to maintain the contrast for the connected regions inside. At the same time eliminate stitching lines by using a weighted fusion spliced algorithm to eliminate the problem of borders outstanding in result of intensity roughness. Finally, the image is normalized into [0, 255] by linear stretch. Experimental results indicate that the proposed algorithm not only can enhance the global contrast but also can preserve local contrast and details.

A palladium-catalyzed decarbonylative alkynylation of amides via C–N bond activation is developed. Compared with the reported Ni/Cu catalyzed reaction, which only proceeded well with silylacetylenes, this transformation was also applicable to both aromatic and aliphatic terminal alkynes, including those bearing functional groups, and thus provided a general and straightforward access to diverse internal alkynes.

Imaging Interferometer (IIM) aboard Chang'E-1 is a Fourier transform imaging spectrometer, with goals to analyze the abundance and distribution of chemical elements on the lunar surface. IIM data suffer from various degradations, which will lead to misleading interpretations of IIM data and inaccuracy of subsequent applications. In this paper, we introduced a noise reduction method based on low-rank matrix decomposition theory. The restoration results are expected to have a better performance in image quality and spectral signatures according to visual and quantitative assessments. Meanwhile, we analyze the characteristic of the noise separated from IIM data using top spectral view of noise cube. The preliminary analysis of the noise characteristics contribute to optimize the data preprocessing of IIM data such as spectrum reconstruction and radiometric correction.

A selective oxidative para-acylation of unprotected anilines with methyl groups in N-heteroarylmethanes was achieved. This transformation proceeds under mild metal-free reaction conditions to produce the corresponding valuable diarylmethanones in good to high yields, featuring high site-selectivity, high functional-group-tolerance, gram-scale synthesis and easy product-derivation. Preliminary mechanistic studies revealed that the present oxidative para-acylation would take place via a Friedel–Crafts-type process of in situ imines and the steric hindrance might be the key issue for the high regio-selectivity.

Under an oxygen atmosphere, the copper-mediated direct C3-cyanation of indole C–H bonds, using cheap and safe DMF as a CN source, took place selectively to produce the corresponding C3-cyanoindoles in good yields. A possible mechanism for this selective cyanation was proposed.

The mechanism of the palladium-catalyzed cross dehydrogenative coupling of P(O)–H compounds with terminal alkynes was studied. Successive ligand-exchange reactions of Pd(OAc)2 with a hydrogen phosphoryl compound and a terminal alkyne take place readily to replace the two acetates on palladium, producing the corresponding (phosphoryl) (alkynyl)palladium complexes, which upon heating decomposed to the corresponding alkynylphosphorus compound. It is also confirmed that in the stoichiometric reactions of the complexes, the configuration at phosphorus is retained. On the basis of these stoichiometric reactions, an efficient synthesis of P-chiral alkynylphosphoryl compounds via palladium-catalyzed stereoselective cross dehydrogenative coupling of P-chiral P(O)–H compounds with terminal alkynes was developed. The key palladium complexes and the stereochemistry of the chiral phosphorus compounds are all unambiguously determined by single-crystal X-ray analysis.

The first copper-catalyzed aerobic oxidative C(aryl)OH bond functionalization of catechols is reported. Under air, at room temperature, in the presence of a copper catalyst, catechols react with amines to produce the corresponding benzoxazoles in high yields. Mechanistic studies suggest that the reaction proceeds via an intriguing competitive oxidation and a synergetic catalysis between catechol and amine.

The Ni-catalyzed direct C-H/C-O cross couplings of benzylic alcohol derivatives with fluorobenzenes and heteroarenes are disclosed. This transformation provides a straightforward and efficient method for the synthesis of these valuable heteroatom-containing compounds.

Iron-catalyzed aerobic oxidative functionalization of sp3 C–H bonds has been developed for the construction of N-heterocycles from easily available carboxylic acid derivatives and o-substituted anilines. This transformation represents a widely applicable protocol to N-heterocycles using biofriendly iron as a catalyst in combination with molecular oxygen or air as the sole oxidant.

Copper-catalyzed aerobic oxidative esterification of P(O)–OH compounds is achieved using alcohols as efficient esterification reagents, giving the expected products with good to moderate yields. Furthermore, it is shown that the arylation of P(O)–OH compounds proceeds efficiently to produce the corresponding products via the treatment of diaryliodonium triflates under mild reaction conditions. It is a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic starting materials with good to excellent yields. The protocol is convenient for practical application. A plausible mechanism has been proposed for the reaction.

A novel base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides has been developed. The protocol is practical, representing a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic starting materials with good to excellent yields. A plausible mechanism was proposed for this reaction.

Copper porphyrin-catalyzed Glaser–Hay-type couplings of terminal alkynes generating 1,3-diynes are described. This reaction features high TON (up to 950) and is complete in an hour, providing a facile, clean, and efficient protocol to access various 1,3-diynes including those with functional groups under mild reaction conditions. This transformation would take place via a radical process.

A novel and efficient t-BuOK-mediated reductive addition of P(O)–H compounds to terminal alkynes was developed. A variety of β-arylphosphine oxides including the valuable β-heteroarylphosphine oxides were produced in moderate to high yields under mild reaction conditions. This reaction may proceed via a tandem process involving regio-selective double addition and subsequent transfer hydrogenation.

A coupling of multiple C(sp

A facile and general Bronsted acid-catalyzed deuteration at the methyl group of N-heteroarylmethanes was achieved through a dearomatic enamine intermediate under relatively mild reaction conditions. Both 2-methyl and 4-methyl groups in quinolines were deuterated with high deuterium incorporation. Pyridines, benzo[d]thiazoles, indoles and imines including these clinical drugs were also deuterated efficiently at the methyl groups. This reaction could be conducted on a large scale (500 mmol), showing its good potential for use in large-scale synthesis.