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.

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.

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.

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.

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 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.

[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.

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.

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.

[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.

[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.

[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.

[The applications of fourier transform infrared spectroscopy in resolving some taxonomic doubts of Caprifoliaceae].

Fourier transform infrared spectroscopy (FTIR) provides biochemical profiles containing overlapping signals from a majority of the compounds that are present when whole.samples are analyzed. The spectra of the xylem of 112 samples belonging to 12 species and 5 genera in Caprifoliaceae were determined directly with FTIR spectrometry and OMNI-sampler. Based on the indices of wave number -absorbance, the phylogenetic relationships of the 12 species were analyzed by the methods of principal coordinate analysis (PCO) and cluster analysis. The results showed that the infrared spectra of the 12 plant species are finger-print-like patterns which are highly typical for different taxa. Genus Heptacodium has close relation with the tribe Linnaeeae, and Lonicereae, showing that its systematic position is probably located between the two tribes. There is no obvious difference between Viburnum and Sambucus, so the authors thought it would be better to put the two genera in Caprifoliaceae. Therefore, the infrared spectra are of taxonomic value at the level of species and genera, and this technique could be widely used for identification and classification of other taxa when standard spectra are available.

[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.

[Application of HATR-FTIR spectroscopy to the analysis of quality mensuration of rhizoma Atractylodes].

The present paper used many kinds of mensuration of FTIR spectroscopy to determine traditional Chinese drugs--rhizoma atractylodis macrocephalae. Comparing the horizontal attenuated total reflection-Fourier transform infrared spectra (HATR-FTIR) of xylem and outer layer parts of cuticle indicates that there are more butenolide and its derivatives in outer layer parts of cuticle. Much more chemical materials could be found in fresh sample than in drying sample, possibly due to the decreased amount of naphtha in the drying sample. The HATR-FTIR of xylem of rhizoma atractylodis macrocephalae and its confusable varieties were transformed into second derivative FTIR to make sure whether the peak location is consistent. As a result, the difference is significant.

[Identification of semen celosiae and semen celosiae cristatae using continuous wavelet transform with FTIR].

Infrared spectra of semen celosiae and semen celosiae cristatae were obtained directly, quickly and accurately by Fourier transform infrared spectroscopy (FTIR) with OMNI sampler. Continuous wavelet transform was used to extrude local region of infrared spectra of semen celosiae and its confusable varieties. The difference of infrared spectra between semen celosiae and semen celosiae cristatae was extruded greatly. Accurate identification rate was improved greatly. Morlet wavelet, which can detect singular values of signal effectively, was selected as the mother wavelet. One-dimensional continuous wavelet transform was implemented for the infrared spectra of semen celosiae and its confusable varieties. The difference between semen celosiae and semen celosiae cristatae was observed at all scales in the wavelet domain. An optimal scale, at which the difference between semen celosiae and semen celosiae cristatae was the most obvious, was selected to identify semen celosiae and semen celosiae cristatae. The results show that it is effective to apply continuous wavelet transform on the basis of FTIR to identify the traditional Chinese medicinal materials, which are the same genus but different species.

[Application of FTIR spectroscopy to the analysis of quality mensuration of Paeonia lactiflora Pall. from native habitat].

In the present paper, different mensurations of Fourier transform infrared spectra for the analysis of Paeonia lactiflora Pall. were compared. FTIR mensurement was applied to the analysis of quality of xylem and outer layer of Paeonia lactiflora Pall. from native habitat. The results revealed that the chemical contents are the same in both the xylem and outer layer of Paeonia lactiflora Pall.. But outer layer has less paeoniflorin and its derivatives than in xylem of Paeonia lactiflora Pall. Different habitats of xylem of Paeonia lactiflora Pall.. were Hanzhou, Anhui and Sichuan. The results indicated that the quality with habitat in Zhejiang is the best among the three.

[Identification of rhizoma atractylodes based on FTIR spectra and radial basis function network].

In order to recognize the atractylodes macrocephala Koidz. (rhizoma atractylodes) and its confusable varieties, three kinds of models of radial basis function network(RBF), nonlinear-linear, linear-linear, and nonlinear-nonlinear model, were used combined with their Fourier transform infrared spectra (FTIR). Rhizoma atractylodes models were collected by Fourier transform infrared spectra, 36 samples were gathered as a training target, and 27 samples as a test set, then their supervision training was performed using three models each. When the summation of error square of the training target was selected as 0. 01, the correct rate for recognition of Fourier transform infrared spectra using each RBF was 100% for the training set, but was different for the test set, which depended on the number of mode in hidden layer, S1. It was found that with the increase of S1, the correct rate would decrease oppositely. This may be caused by the high degree of the nonlinearity of the networks, so that the models of networks were not fit for the training of this kind of sample set. When using linear-linear model of RBF, the correct rate varied with S1 to some extent, but was generally about 85%. Recognizing ability obtained using nonlinear-linear model of RBF was the best. Its correct rate of recognition was >97%. When S1 =3, and so this method can be used to recognize atractylodes macrocephala Koidz. (rhizoma atractylodes) and its confusable varieties simply, rapidlly and accurately.