Advances in flavonoid research since 1992.

Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo- and transition-metal catalysis. The most challenging transformation remains the formation of the parent C-F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal-fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost-efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.

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Introduction of Fluorine and Fluorine-Containing Functional Groups

Donor-acceptor-substituted cyclopropane derivatives and their application in organic synthesis.

The present invention relates to novel organic electroluminescent compounds exhibiting high luminous efficiency, and organic electroluminescent devices comprising the same. The organic electroluminescent compounds according to the invention are represented by Chemical Formula (1):

Novel organic electroluminescent compounds and organic electroluminescent device using the same

Alcohols can be temporarily converted into carbonyl compounds by the metal-catalysed removal of hydrogen. The carbonyl compounds are reactive in a wider range of transformations than the precursor alcohols and can react in situ to give imines, alkenes, and α-functionalised carbonyl compounds. The metal catalyst, which had borrowed the hydrogen, then returns it to the transformed carbonyl compound, leading to an overall process in which alcohols can be converted into amines, compounds containing CC bonds and β-functionalised alcohols.

Borrowing hydrogen in the activation of alcohols

Objective: Glioblastoma is the most aggressive and lethal brain tumor in adults with highly invasive properties. In this present study, we explored the effects of Phyllanthus taxodiifolius Beille extract on molecules known to be hallmarks of aggressive glioblastoma including N-cadherin and vimentin, mesenchymal markers, as well as paxillin, a major adaptor protein that regulates the linking of focal adhesions to the actin cytoskeleton. Methods: P. taxodiifolius were air-dried, powdered and percolated with methanol, filtered, concentrated and lyophilized to yield a crude methanol extract. C6 glioblastoma cell line was used in this study. The expression of N-cadherin and vimentin, as well as the activation of paxillin was determined using Western blot analysis. The effect of the extract on focal adhesions and actin cytoskeleton were investigated using immunofluorescence staining and confocal imaging. Results: In the presence of 40 µg/ml Phyllanthus taxodiifolius Beille extract, the expression of N-cadherin and vimentin were significantly decreased (p<0.001 and p<0.05, respectively). Activation of paxillin was also diminished as indicated by a reduction of phosphorylated-paxillin (p<0.01). Consequently, actin stress fibers in glioblastoma cells were abolished as evidenced by the decrease in focal adhesion (p<0.001) and stress fibers numbers (p<0.001). Conclusion: Our study demonstrates for the first time that P. taxodiifolius interferes with multiple key molecules related to pathological hallmarks of glioblastoma. These molecules are involved with cell contacts, focal adhesions, and the formation and stabilization of actin stress fibers, which are required for glioblastoma metastatic behavior. These results provide further evidence supporting the potential of P. taxodiifolius and its bioactive compounds as anti-cancer agents.

Phyllanthus taxodiifolius Beille Disrupted N-cadherin, Vimentin, Paxillin and Actin Stress Fibers in Glioblastoma

The first phytochemical investigation of the leaves and twigs of Santisukia pagetii (Bignoniaceae) using a bioassay-guided fractionation led to the isolation and identification of seventeen known c...

Anti-HIV-1 Activities and Chemical Constituents from Leaves and Twigs of Santisukia pagetii (Bignoniaceae)

An asymmetric synthesis of gem-difluoromethylenated dihydroxypyrrolizidines and indolizidines is described. The fluoride-catalyzed nucleophilic addition of PhSCF2SiMe3 (1) to chiral imides was achieved in satisfactory yields to provide mixtures of syn- and anti-isomers 6–9 with moderate to good diastereoselectivities. Reductive cleavage of the phenylsulfanyl group followed by intramolecular radical cyclization of the syn-isomers 6–9 occurred under refluxing conditions to afford the corresponding gem-difluoromethylenated 1-azabicyclic compounds 10–13 in moderate yields as a separable mixture of cis- and trans-isomers. The cis-isomers of compounds 10 and 12 and trans-13 were readily transformed to gem-difluoromethylenated dihydroxypyrrolizidines 20 and 27 and indolizidine 28, respectively, by reductive cleavage of the hydroxyl group and organometallic addition followed by hydrogenolysis.

Asymmetric Synthesis of gem‐Difluoromethylenated Dihydroxypyrrolizidines and Indolizidines.

Naturally Occurring 1,7‐Diarylheptanoids

The MoritaBaylisHillman (MBH) reactions of (4S,5R,7R,8R)- and (4R,5R,7R,8R)-4-hydroxy-7,8-dimethoxy-7,8-dimethyl-6,9-dioxaspiro[4.5]dec-2-en-1-ones (2 and 3, resp.) with aldehydes using various catalysts were studied. A combination of Bu3P/phenol in THF was found being optimum conditions giving the corresponding MBH adducts with high diastereoisomeric ratios. After separation, each stereomerically pure isomer of the MBH adducts was subjected to hydrolysis employing 1% aq. CF3COOH (TFA) in a water bath of an ultrasonic cleaner to afford the corresponding polyhydroxylated cyclopentenones in good yields.

Patoomratana Tuchinda

Papers

Phyllanthus taxodiifolius Beille Disrupted N-cadherin, Vimentin, Paxillin and Actin Stress Fibers in Glioblastoma

Anti-HIV-1 Activities and Chemical Constituents from Leaves and Twigs of Santisukia pagetii (Bignoniaceae)

Asymmetric Synthesis of gem‐Difluoromethylenated Dihydroxypyrrolizidines and Indolizidines.

Naturally Occurring 1,7‐Diarylheptanoids

The MoritaBaylisHillman Reaction of Chiral Highly Oxygenated Cyclopent‐2‐enones