Internal Alkyne-Directed Fluorination of Unactivated C(sp3)-H Bonds.

A silver-mediated internal alkyne-guided fluorination of unactivated C(sp3)-H bonds is described. The reaction provides a facile access to γ-fluorinated fluoroalkylated (Z)-alkenes from readily available alkynes in promising yields with excellent regioselectivity, stereoselectivity, and site selectivity.

Synthesis of Polysubstituted Pyrroles via Silver-Catalyzed Oxidative Radical Addition of Cyclopropanols to Imines.

A silver-catalyzed formal [3 + 2] cycloaddition reaction, with cyclopropanols as a C3 subunit and imines as a two-atom subunit, is developed. The reaction takes place under mild conditions and produces a broad array of polysubstituted pyrroles in medium to high yields. It represents the first example of oxidative radical addition to imines, thus offering a new choice for the direct C-H functionalization of imines.

Iron-catalyzed domino Knoevenagel-hetero-Diels-Alder reaction: facile access to oxabicyclo[3.3.1]nonene derivatives.

A Fe-catalyzed domino Knoevenagel-hetero-Diels-Alder reaction of alkenyl aldehydes and 1,3-diketones has been developed. It provides straightforward access to a series of oxabicyclo[3.3.1]nonene derivatives in promising yields with excellent diastereoselectivity and functional group tolerance. The resultant bridged dihydropyrans can be smoothly converted into chromene derivatives, thus highlighting the synthetic utility of this method.

Copper-catalyzed remote oxidation of alcohols initiated by radical difluoroalkylation of alkenes: facile access to difluoroalkylated carbonyl compounds.

A Cu-catalyzed oxidation of alcohols triggered by the radical difluoroalkylation of alkenes has been developed, providing facile access to a series of difluoroalkylated ketones or aldehydes in moderate to high yields. The concurrent realization of the catalytic oxidation of alcohols and difluoroalkylation of alkenes enables a highly efficient and attractive method for organic synthesis.

Palladium-Catalyzed Site-Selective sp3 C-H Bond Thiocyanation of 2-Aminofurans.

Alkyl thiocyanates are prevalent in natural products, drugs, and biologically active compounds. We report here a novel, mild, and efficient Pd-catalyzed site-selective sp3 C-H bond thiocyanation of 2-aminofurans. Using Na2S2O8 as the oxidant and readily available NaSCN as the thiocyanation reagent, the kinetically favorable 2-amino-4-thiocyanatomethylfurans are selectively synthesized in promising yields with a broad substrate scope. This reaction represents the first example of transition-metal-catalyzed site-selective sp3 C-H bond thiocyanation, thus offering a novel strategy for the step- and atom-economic synthesis of alkyl thiocyanates.

Preparation of 2-Amino-5-homoallylfurans via Palladium-Catalyzed Tandem Cycloisomerization/Heck-Type Coupling of Homoallenyl Amides with Allyltrialkylsilanes.

The direct access to 2-amino-5-homoallylfurans has been realized by a palladium-catalyzed tandem cycloisomerization/Heck-type coupling between homoallenyl amides and allyltrialkylsilanes, using a novel DDQ/MnO2 combination as the efficient oxidant. The reaction exclusively affords γ-allylation products in good to excellent yields with broad substrate scope under exceptionally mild reaction conditions. It represents one of the rare examples of the Pd-catalyzed intermolecular Heck-type coupling of allytrialkylsilanes terminated by ß-silyl elimination, thus complementing traditional allylation methods because of the excellent γ-selectivity.

Palladium-Catalyzed Remote Aryldifluoroalkylation of Alkenyl Aldehydes.

A palladium-catalyzed three-component reaction between fluoroalkyl bromides, arylboronic acids, and alkenyl aldehydes has been developed and provides facile access to 5-, 6-, or 7-difluoroalkylated ketones under very mild reaction conditions. The resultant products can be smoothly converted into CF2 -containing tetrahydronaphthalenes by a novel silver-catalyzed intramolecular decarboxylative cyclization of 5-aryl-2,2-difluoropentanoic acids.

Copper-Catalyzed Trifluoromethylation of Alkenes with Redox-Neutral Remote Amidation of Aldehydes.

A room-temperature and one-pot synthesis of ε-CF3-substituted amides via the copper-catalyzed trifluoromethylation of alkenes with redox-neutral remote amidation of aldehydes is described. This reaction is featured by an unprecedented 1,5-H atom abstraction from aldehydic C-H bonds by α-CF3-alkyl radicals resulting from the radical trifluoromethylation of alkenes, thus enabling a new possibility of the trifluoromethylation-initiated remote sp(2) C-H functionalization.

Divergent Synthesis of 2-Aminofurans via Palladium-Catalyzed Acetoxylative, Alkoxylative, and Hydroxylative Cycloisomerization of Homoallenyl Amides.

A fine-tunable transformation, including Pd-catalyzed acetoxylative, alkoxylative, and hydroxylative cycloisomerization of homoallenyl amides, has been realized with hypervalent iodine organic compounds as the oxidants, giving polysubstituted 2-aminofurans in promising yields at room temperature. The selective formation of three different types of products from the same starting materials makes this reaction particularly attractive and useful for organic synthesis.

Palladium-catalyzed cycloisomerization and aerobic oxidative cycloisomerization of homoallenyl amides: a facile and divergent approach to 2-aminofurans.

A Pd-catalyzed divergent cyclization, including cycloisomerization and aerobic oxidative cycloisomerization of homoallenyl amides, is described. Varieties of functionalized 2-amino-5-alkylfurans and 2-amino-5-formylfurans can be selectively synthesized in good to excellent yields. Preliminary mechanistic studies show that peroxide may be a key intermediate for this Pd-catalyzed radical aerobic oxidative cycloisomerization of homoallenyl amides. The mild reaction conditions, high atom economy, and utilization of air as the oxygen source make this protocol very environmentally benign and practical to the synthetic community.

Study on the Identification of Radix Bupleuri from Its Unofficial Varieties Based on Discrete Wavelet Transformation Feature Extraction of ATR-FTIR Spectroscopy Combined with Probability Neural Network.

The attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was employed to acquire the infrared spectra of Radix Bupleuri and its unofficial varieties: the root of Bupleurum smithii Wolff and the root of Bupleurum bicaule Helm. The infrared spectra and spectra of Fourier self-deconvolution (FSD), discrete wavelet transform (DWT), and probability neural network (PNN) of these species were analyzed. By the method of FSD, there were conspicuous differences of the infrared absorption peak intensity of different types between Radix Bupleuri and its unofficial varieties. But it is hard to tell the differences between the root of Bupleurum smithii Wolff and the root of Bupleurum bicaule. The differences could be shown more clearly when the DWT was used. The research result shows that by the DWT technology it is easier to identify Radix Bupleuri from its unofficial varieties the root of Bupleurum smithii Wolff and the root of Bupleurum bicaule.

Research of Recognition Method of Discrete Wavelet Feature Extraction and PNN Classification of Rats FT-IR Pancreatic Cancer Data.

Sprague-Dawley (SD) rats' normal and abnormal pancreatic tissues are determined directly by attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy method. In order to diagnose earlier stage of SD rats pancreatic cancer rate with FT-IR, a novel method of extraction of FT-IR feature using discrete wavelet transformation (DWT) analysis and classification with the probability neural network (PNN) was developed. The differences between normal pancreatic and abnormal samples were identified by PNN based on the indices of 4 feature variants. When error goal was 0.01, the total correct rates of pancreatic early carcinoma and advanced carcinoma were 98% and 100%, respectively. It was practical to apply PNN on the basis of ATR-FT-IR to identify abnormal tissues. The research result shows the feasibility of establishing the models with FT-IR-DWT-PNN method to identify normal pancreatic tissues, early carcinoma tissues, and advanced carcinoma tissues.

Palladium-catalyzed hydroarylation, hydroalkenylation, and hydrobenzylation of ynol ethers with organohalides: A regio- and stereoselective entry to α,ß- and ß,ß-disubstituted alkenyl ethers.

A Pd-catalyzed reductive addition of organohalides, including aryl, alkenyl, and benzyl halides, to ynol ethers has been realized in the presence of 2-propanol, giving α,ß- and ß,ß-disubstituted olefinic ethers in satisfactory yields with excellent regio- and stereoselectivity. It represents the first highly regio- and stereoselective hydroarylation, hydroalkenylation, and hydrobenzylation of ynol ethers.

Recognition of FT-IR Data Cuscutae Semen, Japanese Dodder, and Sinapis Semen Using Discrete Wavelet Transformation and RBF Networks.

Horizontal attenuation total reflection Fourier transformation infrared spectroscopy (HATR-FT-IR) studies on cuscutae semen and its confusable varieties Japanese dodder and sinapis semen combined with discrete wavelet transformation (DWT) and radial basis function (RBF) neural networks have been conducted in order to classify them. DWT is used to decompose the FT-IRs of cuscutae semen, Japanese dodder, and sinapis semen. Two main scales are selected as the feature extracting space in the DWT domain. According to the distribution of cuscutae semen, Japanese dodder, and sinapis semen's FT-IRs, three feature regions are determined at detail 3, and two feature regions are determined at detail 4 by selecting two scales in the DWT domain. Thus five feature parameters form the feature vector. The feature vector is input to the RBF neural networks to train so as to accurately classify the cuscutae semen, Japanese dodder, and sinapis semen. 120 sets of FT-IR data are used to train and test the proposed method, where 60 sets of data are used to train samples, and another 60 sets of FT-IR data are used to test samples. Experimental results show that the accurate recognition rate of cuscutae semen, Japanese dodder, and sinapis semen is average of 100.00%, 98.33%, and 100.00%, respectively, following the proposed method.

[Analysis and comparison of trace elements of herba euphorbiae humifusae in different periods by microwave digestion-atomic absorption spectroscopy].

Herba euphorbiae humifusae is the dried whole plant of Euphorbia humi fusa Willd. that belongs to euphorbiaceae. In the present paper, the microwave digestion procedure was used to digest herba euphorbiae humifusae collected in different periods, and then flame atomic absorption spectrometry (FAAS) was used to determine the contents of eight kinds of trace elements of herba euphorbiae humifusae in different periods, and the change in the contents of trace elements at different times was studied and analysed. The results showed that of all the trace elements of herba euphorbiae humifusae in different periods, element Fe was the highest in June, element K was in August at the highest level, element Mn reached the highest content in September, elements Na and Ca were dividedly at the highest content in October and November, and in December the highest content elements were Zn, Cu and Mg. In one word, the change of Na and Ca was jumping, while the change of Cu and Zn was comparatively mild. The results provide scientific basis for the time of collection of herba euphorbiae humifusae.

[Studies on the Herba Plantaginis of different kinds and habitats by FTIR reflection spectroscopy-chemometrics analysis].

In the present paper, FTIR of different species obtained from different regions of sibling plantaginis were determined by Fourier transform infrared reflection spectroscopy (FTIRS), and thirty-five comparatively typical absorption peaks were selected and used to study genetic relationship, combined with chemometric methods. The phylogenetic cluster analysis revealed that three species could be divided into two groups based on the distance of 0.036, among which Plantago depressa Willd. was clustered with Plantago asiatica L. based on distance of 0.033, while clustered with Plantago virginica L. based on distance of 0.042, and the result was consistent with that of traditional taxology. The principal component analysis result revealed that the distances of Plantago asiatica L. in the similar environment are similar in three-dimensional FTIR chart, however, it is dispersive when obtained from different regions. This method is scientific, simple and direct, and has important theoretical and practical application value.

[Identification of Papaver somni ferum L. and Papaver rhoeas using DSWT-FTIR-RBFNN].

Infrared spectra of Papaver somniferum L. and Papaver rhoeas were obtained directly, quickly and accurately by Fourier transform infrared spectroscopy (FTIR)with OMNI sampler. Discrete stationary wavelet transform was used to extrude local region of infrared spectra of Papaver somniferum L. and Papaver rhoeas. The difference of infrared spectra between Papaver somniferum L. and Papaver rhoeas was extruded. Accurate identification rate is improved greatly. One dimensional discrete stationary wavelet transform was implemented to the infrared spectra of Papaver somniferum L. and Papaver rhoeas. The difference between Papaver somniferum L. and Papaver rhoeas was observed at all scales in wavelet domain. Two scales, at which the difference between Papaver somniferum L and Papaver rhoeas is the most obvious, were selected to extract the features of Papaver somniferum L. and Papaver rhoeas. A feature vector including eight feature parameters was constructed. The feature vector was input to RBFNN for training in order to accurately identify Papaver somniferum L. and Papaver rhoeas. In experiment, the authors used one hundred and twenty-eight couples of data of Papaver somniferum L. and Papaver rhoeas (including seventy-eight couples of training samples and fifty couples of testing samples). The experimental results show that it is effective to apply discrete stationary wavelet transform on the basis of FTIR to identify the Papaver somniferum L. and Papaver rhoeas. The accurate identification rate of Papaver somniferum L and Papaver rhoeas is 99.8% and 99.9% respectively.

[Comparison and correlative analysis of trace elements in five kinds of radix curcumae].

Traditional Chinese medicine materials (TCM) contained abundant trace elements needed in human body. Mixed acid (HNO3:HClO4) was added into samples treated by microwave digestion, and a systematic study was carried out by selection of the most appropriate working conditions and optimization of the sample mass. Some inorganic elements in 5 kinds of radix curcumae (Curcuma wenyujin Y. H. Chen et C. Ling, Curcuma longa L., Curcuma kwangsiensis S. G. Lee et C. F. Liang, Curcuma phaeocaulis Val. and Curcuma chuanyujin C. K Hsieh et H. Zhang) necessary to lives were determined by flames atomic absorption spectrometry (AAS). Elements, such as K, Ca, Na, Mg, Zn, Fe, Cu and Mn were detected. The results show that there are similar elements in the five kinds of radix curcumae, while differences only exist in a few elements contents. The correlative analysis of trace elements in samples was carried out by cluster analysis of the 4 kinds of radix curcumae (Curcuma wenyujin Y. H. Chen et C. Ling, Curcuma longa L., Curcuma kwangsiensis S. G. Lee et C. F. Liang and Curcuma phaeocaulis Val. ) in codex populations in a cluster, different from the unofficial sample (Curcuma chuanyujin C. K. Hsieh et H. Zhang). The cluster analysis results are consistent with the morphological characteristics of the traditional taxonomy results. The results showed that the analytic method is advisable. This paper provides scientific basis for deeply studing the relation between trace elements and drug effect of radix curcumae.

[Determination of trace elements in radix Paeoniae alba by microwave digestion-ICP-AES].

Microwave digestion technique was used in the decomposition of radix Paeoniae alba samples of different growing area, different growing time and before and after processing, and the contents of K, Ca, Na, Mg, Zn and Fe were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results of the determination show that radix Paeoniae alba samples are rich in the trace elements. The RSDs of these elements were lower than 4%, and the recovery ratio ranged between 99% and 113%. The results revealed that the analytic method is sensitive and precise. The pattern recognition based on the principal component analysis (PCA) was applied to the measured trace elements of different radix Paeoniae alba samples. The PCA was useful in the classification of radix Paeoniae alba. This paper provides scientific basis for deeply studying the relation between the trace elements and the drug effect of radix Paeoniae alba.

[Study on identification of Gastrodia elata Bl. by Fourier self-deconvolution infrared spectroscopy].

In the present article the FTIR spectra of the wild and planting Gastrodia elata Bl. from different habitats and its confusable varieties such as Canna edulis Ker-Gawl, Colocasia esculenta (L.) Schott and Solanum tuberosum L. were obtained by horizontal attenuated total reflection infrared spectroscopy (HATR-FTIR), and were all transformed by Fourier self-deconvolution. The authors investigated the discrepancy extent of Fourier self-deconvolution of Gastrodia elata Bl and confusable varieties under various bandwidth and enhancement, and found that the discrepancy extent of Gastrodia elata Bl and confusable varieties was the most obvious when the bandwidth was between 75.0 and 76.0 and enhancement was 3.2. By adopting Fourier self-deconvolution infrared spectroscopy (FSD-IR) analytical method the samples were studied in detail. The results showed that we could find out the difference among them by means of Fourier self-deconvolution infrared spectroscopy, although it was very difficult to find out the difference in FSD-IR spectra of wild and planting Gastrodia elata Bl., and asexual reproduction and sexual reproduction Gastrodia elata Bl. The difference in FSD-IR spectra between Gastrodia elata Bl. and its confusable varieties is also very great. Therefore, this method can be used to recognize different Gastrodia elata Bl. and its confusable varieties simply, rapidly and accurately.