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Difluorocarbene is a versatile and efficient intermediate for fluorine incorporation. Here, the authors show that difluorocarbene can be oxidized to carbonyl fluoride and this process is confirmed in 18O-trifluoromethoxylation reactions, by observation of AgOCF3 species and theory.

Abstract Background Proline (Pro) and γ-aminobutyric acid (GABA) play important roles in plant development and stress tolerance. However, the molecular components responsible for the transport of these molecules in rice remain largely unknown. Results Here we identified OsProT1 and OsProT3 as functional transporters for Pro and GABA. Transient expression of eGFP-OsProTs in plant protoplasts revealed that both OsProT1 and OsProT3 are localized to the plasma membrane. Ectopic expression in a yeast mutant demonstrated that both OsProT1 and OsProT3 specifically mediate transport of Pro and GABA with affinity for Pro in the low affinity range. qRT-PCR analyses suggested that OsProT1 was preferentially expressed in leaf sheathes during vegetative growth, while OsProT3 exhibited relatively high expression levels in several tissues, including nodes, panicles and roots. Interestingly, both OsProT1 and OsProT3 were induced by cadmium stress in rice shoots. Conclusions Our results suggested that plasma membrane-localized OsProT1 and OsProT3 efficiently transport Pro and GABA when ectopically expressed in yeast and appear to be involved in various physiological processes, including adaption to cadmium stress in rice plants.

Summary: The CF3O functional group is a unique fluorinated group that has received a great deal of attention in medicinal chemistry and agrochemistry. However, trifluoromethoxylation of substrates remains a challenging task. Herein we describe the dehydroxytrifluoromethoxylation of alcohols promoted by a R3P/ICH2CH2I (R3P = Ph3P or Ph2PCH=CH2) system in DMF. P-I halogen bonding drives the reaction of R3P with ICH2CH2I in DMF to generate iodophosphonium salt (R3P+I I−) and a Vilsmeier-Haack-type intermediate, both of which could effectively activate alcohols, thus enabling a fast (15 min) trifluoromethoxylation reaction. A wide substrate scope and a high level of functional group tolerance were observed. : Chemistry; Organic Chemistry; Organic Synthesis Subject Areas: Chemistry, Organic Chemistry, Organic Synthesis

Carbon based nucleophiles often are synthetically limited by the high basicity/reactivity of the starting materials. Here, the authors show that tetraarylphosphonium salts can be induced to act as C-aryl nucleophiles for the addition to carbonyls and imines.

An efficient method for the copper-catalyzed trifluoromethylation of terminal alkenes with an electrophilic trifluoromethylating reagent has been developed. The reactions proceeded smoothly to give trifluoromethylated alkenes in good to excellent yields. The results provided a versatile approach for the construction of Cvinyl–CF3 bonds without using prefunctionalized substrates.

Due to its unique electronic properties, the difluoromethylene group (CF 2) has served as a valuable unity in the design of biologically active molecules. Since γ-lactones display a broad range of biological properties, α,α-difluoro-γ-lactones may exhibit unexpected biological activities, and thus their synthesis has received increasing attention. Traditional synthetic methods suffer from tedious multi-step processes, and very few effective methods have been reported recently. Herein, we describe the difunctionalization of alkenes with BrCF2CO2K under photoredox catalysis with the use of a boron-Lewis acid for the access to α,α-difluoro-γ-lactones. In this transformation, the alkene substrates and the used reagents, including BrCF2CO2K and the boron-Lewis acid, PhB(OH) 2 or BF3• THF, are cheap and widely available. High efficiency and atom economy may make this protocol attractive. [ABSTRACT FROM AUTHOR]

Ph3P/I–-promoted dichlorination and dibromination of epoxides by using XCH2CH2X (X = Cl or Br) as the halogen source and reaction solvent is described. All reagents are widely available and easy to handle, and mild conditions and operational simplicity make this protocol attractive. [ABSTRACT FROM AUTHOR]

An efficient reagent system, Ph3P/XCH2CH2X (X = Cl, Br, or I), was very effective for the deoxygenative halogenation (including fluorination) of alcohols (including tertiary alcohols) and aldehydes. The easily available 1,2-dihaloethanes were used as key reagents and halogen sources. The use of (EtO)3P instead of Ph3P could also realize deoxy-halogenation, allowing for a convenient purification process, as the byproduct (EtO)3P≡O could be removed by aqueous washing. The mild reaction conditions, wide substrate scope, and wide availability of 1,2-dihaloethanes make this protocol attractive for the synthesis of halogenated compounds. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor receptor-associated protein-1 (TRAP-1), a mitochondrial chaperone, contributes significantly to the progression of cancer. However, the understanding of its involvement in the clinicopathological characteristics and prognosis of colorectal cancer (CRC) remains limited. The aim of the present study was to assess the significance of TRAP-1 expression in CRC. The expression of TRAP-1 was evaluated in corresponding cancerous, paracancerous, lymph node and distant metastatic tissues of 256 cases of CRC by immunohistochemistry. The associations between TRAP-1 expression and the clinicopathological parameters and survival rates of patients was assessed. Out of 256 patients with CRC, TRAP-1 expression was detected in 203 (79.3%). TRAP-1 expression was significantly increased in cancerous tissue compared with that in corresponding paracancerous tissues (P<0.001). Overexpression of TRAP-1 was significantly associated with differentiation (P=0.011), depth of invasion (P=0.006), lymph node metastasis (P<0.001) and tumor-node-metastasis stage (P<0.001). In patients with high TRAP-1 expression, the 5-year overall survival (OS) rate was 38.0%, in contrast to 56.5% in patients with low TRAP-1 expression (P=0.003). Similarly, the 5-year progression-free survival (PFS) was 26.6% for patients with high TRAP-1 expression and 53.3% for patients with low TRAP-1 expression (P<0.001). Multivariate analyses indicated the TRAP-1 expression is an independent prognostic factor for poorer OS [P=0.015; hazard ratio (HR), 1.914] and PFS (P<0.001; HR, 2.534). Thus, TRAP-1 may serve as a potential biomarker for predicting the prognosis of patients with CRC. Specifically, overexpression of TRAP-1 may predict progression and poor survival in cases of CRC. [ABSTRACT FROM AUTHOR]

In this study, the distribution characteristics of scale height at various solar activity levels were statistically analyzed using the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) radio occultation data for 2007-2013. The results show that: (1) in the mid-high latitude region, the daytime (06-17LT) scale height exhibits annual variations in the form of a single peak structure with the crest appearing in summer. At the high latitude region, an annual variation is also observed for nighttime (18-05LT) scale height; (2) changes in the spatial distribution of the scale height occur. The crests are deflected towards the north during daytime (12-14LT) at a geomagnetic longitude of 60°W-180°W, and they are distributed roughly along the geomagnetic equator at 60°W-180°E. In the approximate region of 120°W-150°E and 50°S-80°S, the scale height values are significantly higher than those in other mid-latitude areas. This region enlarges with increased solar activity, and shows an approximately symmetric distribution about 0° geomagnetic longitude. Nighttime (00-02LT) scale height values in the high-latitude region are larger than those in the low-mid latitude region. These results could serve as reference for the study of ionosphere distribution and construction of the corresponding profile model. [ABSTRACT FROM AUTHOR]

The study of transition-metal difluorocarbene complex has long been a subject of active investigation, but the transition-metal-catalyzed transfer of difluorocarbene remains a significant challenge. The Pd-catalyzed transfer of difluorocarbene is described to realize the coupling reaction of boronic acids with difluorocarbene to give (difluoromethyl)arenes and -olefins. Mechanistic investigations reveal that the Pd-CF2 complex is an important intermediate for this transformation. This complex is prone to trimerization without the presence of starting materials. [ABSTRACT FROM AUTHOR]

Phosphonium salt ([Ph3P+CF2H] Br-, DFPB) was found to be an efficient nucleophilic difluoromethylation reagent. Although DFPB is known as a phosphonium ylide precursor, its reaction with carbonyl compounds under traditional "Wittig reaction conditions" did not give the expected Wittig difluoroolefinated products, but afforded the nucleophilic difluoromethylation products, α-CF2H alcohols. Mechanistic investigation reveals that the unexpected transformation proceeded via the direct transfer of the CF2H group, which resulted from the high P-O affinity. [ABSTRACT FROM AUTHOR]

The trifluoromethylcarbene (:CHCF3) was found to be conveniently generated from (2,2,2-trifluoroethyl)diphenyl-sulfonium triflate (Ph2S+CH2CF3 -OTf), which was successfully applied in Fe-catalyzed cyclopropanation of olefins, giving the corresponding trifluoromethylated cyclopropanes in high yields. [ABSTRACT FROM AUTHOR]

Cross-coupling between difluorocarbene and carbene-derived intermediates generated from diazocompounds was developed to give gem-difluoroolefins, which constitutes a fast practical pathway to achieve hindered gem-difluoroolefins. The cross-coupling between difluorocarbene and aryl diazoacetates proceeded smoothly in the presence of a copper source, whereas its coupling with diaryl diazomethanes occurred well under metal-free conditions. A mechanism involving a copper-difluorocarbene complex was proposed. [ABSTRACT FROM AUTHOR]

Water was found to be a suitable reaction medium for the direct asymmetric aldol reaction of various cyclic ketones with aryl aldehydes catalyzed by a primary-tertiary diamine-Brønsted acid. [ABSTRACT FROM AUTHOR]

This paper proposes a novel data hiding method for JPEG 2000 coded images that embed multi-level information into quantized discrete wavelet transformed coefficients. Since the proposed method hides information represented as an integer to a transformed coefficient rounded to an integer, a JPEG 2000 code-stream conveying data keeps its standard JPEG 2000 code-stream structure. The proposed method is able to extract hidden data without memorizing embedding positions; it thus chooses transformed coefficients to which data is hidden freely. This characteristic makes the proposed method suitable for hiding data to a JPEG 2000 coded image with consideration of Region of Interest (ROI) coding that is a major feature. Simulation results show the effectiveness of the proposed method. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(7): 37– 46, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20286 [ABSTRACT FROM AUTHOR]

Diagnosing nasopharyngeal carcinoma (NPC) is a significant challenge because of the highly complex process. We proposed an approach to diagnose NPC serum using a combination of hyperspectral imaging and weight-based principal component analysis. Samples were prepared by pressing boric acid into pellets for use as the sera substrate. The sera, collected from 100 healthy volunteers and 60 NPC patients, was dripped onto the surface of the substrate for hyperspectral imaging. The characteristic spectral bands were selected based on the variable weight obtained from a support vector machine (SVM) model, using principal component analysis (PCA) to reduce the dimension in the extracted bands. Obtained results show that the accuracy rate, sensitivity, and specificity between the NPC sera and the sera of the healthy controls reached extremely high levels of 99.15%, 98.79%, and 99.36%, respectively. For the model's consistency evaluation, we found that the Kappa and area under the curve (AUC) of the receiver operating characteristic (ROC) curve were 0.99 and 0.98, respectively. These results suggest that the developed approach could serve as a noninvasive diagnostic and screening tool for highly accurate and consistent detection of NPC. Hence, a combination of hyperspectral imaging (HSI) and a weighted principal component analysis (WPCA)-SVM model represents a powerful and promising tool for NPC diagnosis.