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Green organophotocatalysis. TiO<sub>2</sub>-induced enantioselective α-oxyamination of aldehydes
Ho, Xuan-Huong,Kang, Min-Jung,Kim, Seung-Joo,Park, Eun Duck,Jang, Hye-Young Royal Society of Chemistry 2011 Catalysis Science & Technology Vol.1 No.6
<P>Asymmetric C–O bond formation with various aldehydes is examined under conditions of environmentally benign photo-organocatalysis. A heterogeneous TiO<SUB>2</SUB> photocatalyst is used as a photooxidant in place of toxic and expensive chemical oxidants, for the first time in chemo- and stereoselective bond formation.</P> <P>Graphic Abstract</P><P>The photoactivated TiO<SUB>2</SUB>, a green catalyst, was utilized in the asymmetric C–O bond forming organocatalytic reaction for the first time. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cy00183c'> </P>
Quantitative Analysis of Adsorption and Photocatalytic Activity of Vanadium-Oxide Gels and Nanobelts
장혜영,Quang-Thao Ta,Xuan-Huong Ho,모선일 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6
The heterogeneous photocatalytic and adsorption effects of vanadium oxides in various forms (nanocrystalline, organogels, and xerogel) were examined systematically via the degradation of rhodamine B (RhB) under visible light irradiation. The total effect of adsorption and photodegradation of RhB was enhanced greatly by using V2O5 nanobelts or gels compared with commercial crystalline V2O5. The adsorption effect on the V2O5 nanobelts or gels was significant. In particular, adsorption on the vanadium-oxide xerogel was most effective. The expanded surface area with the hydroxyl group on the surface is a critical parameter affecting the adsorption of RhB. The enhanced RhB photodegradation observed in V2O5 nanobelts is attributed to increased light penetration through the V2O5 nanobelts.
Yoon, Hyo-Sang,Ho, Xuan-Huong,Jang, Jiyeon,Lee, Hwa-Jung,Kim, Seung-Joo,Jang, Hye-Young American Chemical Society 2012 Organic letters Vol.14 No.13
<P>A remarkably efficient photosensitizer, N719 dye, was used in asymmetric tandem Michael addition/oxyamination of aldehydes, rendering α,β-substituted aldehydes in good yields with excellent levels of enantioselectivity and diastereoselectivity. This is the first report of a multiorganocatalytic reaction involving iminium catalysis and photoinduced singly occupied molecular orbital (SOMO) catalysis. This reaction is expected to expand the scope of tandem organocatalytic reactions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2012/orlef7.2012.14.issue-13/ol3011858/production/images/medium/ol-2012-011858_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol3011858'>ACS Electronic Supporting Info</A></P>
Organocatalyzed α-Oxyamination of Aldehydes Using Anodic Oxidation
Bui, Nhat-Nguyen,Ho, Xuan-Huong,Mho, Sun-il,Jang, Hye-Young WILEY-VCH Verlag 2009 EUROPEAN JOURNAL OF ORGANIC CHEMISTRY Vol.2009 No.31
<P>Electrochemical oxidation was performed during the organocatalyzed α-oxyamination of aldehydes by using a one-compartment electrolytic cell under galvanostatic conditions. In the presence of substoichiometric amounts of sec-amines, the desired coupling products were formed in good yield. The asymmetric variant of the α-oxyamination of aldehydes was examined by using chiral sec-amines. Control experiments and cyclic voltammetry confirmed the key intermediate of this reaction to be the cationic radical of the enamine derived from the sec-amine catalysts and aldehydes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)</P> <B>Graphic Abstract</B> <P>Anodic oxidation was used to promote the organocatalyzed α-oxyamination of aldehydes. Under galvanostatic conditions, cationic radical intermediates are formed as key intermediates. Cyclic voltammetry and control experiments were carried out to confirm the proposed intermediates and the mechanism of the reaction. <img src='wiley_img/1434193X-2009-2009-31-EJOC200900871-fig000.gif' alt='wiley_img/1434193X-2009-2009-31-EJOC200900871-fig000'> </P>
Tai, Bui Huu,Huyen, Vu Thi,Huong, Tran Thu,Nhiem, Nguyen Xuan,Choi, Eun-Mi,Kim, Jeong Ah,Long, Pham Quoc,Cuong, Nguyen Manh,Kim, Young Ho The Pharmaceutical Society of Japan 2010 Chemical & pharmaceutical bulletin Vol.58 No.4
<P>The new pyrano-pyrone, (+)-8-epi-9-deoxygoniopypyrone (1) and (+)-9-deoxygoniopypyrone (2) were isolated from a chloroform extract of <I>Goniothalamus tamirensis</I> leaves. Their absolute stereostructures were discussed and confirmed by using infrared (IR), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), one (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectra, Mosher's method, and comparison with the known compounds leiocapin A (3), deoxygoniopypyrone A (4), and (−)-8-epi-9-deoxygoniopypyrone (5). At concentrations of 2.67 μ<SMALL>M</SMALL>, compounds 1 and 2 significantly increased the growth of osteoblastic MC3T3-E1 cells and caused a significant elevation of collagen content, alkaline phosphatase activity, and nodule mineralization in the cells (<I>p</I><0.05). Our data suggest that the enhancement of osteoblast function by 1 and 2 may result in the prevention of osteoporosis.</P>
Chemical Constituents of Acanthus ilicifolius L. and Effect on Osteoblastic MC3T3E1 Cells
Kiem, Phan Van,Quang, Tran Hong,Huong, Tran Thu,Nhung, Le Thi Hong,Cuong, Nguyen Xuan,Minh, Chau Van,Choi, Eun-Mi,Kim, Young-Ho 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.7
A new coumaric acid derivative called acancifoliuside (1) and six known compounds as acteoside (2), isoacteoside (3), acanthaminoside (4), (+)-lyoniresinol 3a-O-$\beta$-glucopyranoside (5), (-)-lyoniresinol (6), and $\alpha$-amyrin (7), were isolated from the methanolic extract of the leaves of Acanthus ilicifolius L. (Acanthaceae). Their structures were determined by spectroscopic methods and a comparison with the spectral data reported in the literature. The effects of the compounds on the function of osteoblastic MC3T3-E1 cells were tested. Compounds 2, 3, and 5 ($30\;{\mu}M$) increased the growth and differentiation of osteoblasts significantly (P<0.05), indicating that A. ilicifolius leaves may help prevent osteoporosis.
New Phenylpropanoid Esters of Sucrose from Polygonum hydropiper and Their Antioxidant Activity
Kiem, Phan Van,Nhiem, Nguyen Xuan,Cuong, Nguyen Xuan,Hoa, Tran Quynh,Huong, Hoang Thanh,Huong, Le Mai,Minh, Chau Van,Kim, Young-Ho 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.11
By various chromatographic methods, two new phenylpropanoid esters of sucrose named hidropiperosides A (1) and B (2), and three known compounds as vanicosides A (3), B (4), and E (5) were isolated from the methanolic extract of the whole plant of Polygonum hydropiper L. (Polygonaceae). Their structures were elucidated by extensive spectroscopic methods including 1D- and 2D-NMR experiments, as well as ESI-MS analysis. All the isolated compounds were tested for their antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay system. Among them, compounds 2 and 3 showed significant antioxidant activity with their $SC_{50}$ values of 23.4 and $26.7{\mu}g/mL$, respectively.
Chemical Components from the Vietnamese Soft Coral Lobophytum sp.
Tung, Nguyen Huu,Minh, Chau Van,Kiem, Phan Van,Huong, Hoang Thanh,Nam, Nguyen Hoai,Cuong, Nguyen Xuan,Quang, Tran Hong,Nhiem, Nguyen Xuan,Hyun, Jae-Hee,Kang, Hee-Kyoung,Kim, Young-Ho 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.4
Chromatographic separation resulted in the identification of one new squalene derivative, named lobophytene (1), three cembranoid diterpenes (2-4), and two sterols (5 and 6) from the Vietnamese marine soft coral Lobophytum sp. Their structures were identified on the basis of extensive spectroscopic data and comparison of those with reported data. Compounds 1 and 2 showed significant cytotoxic activities against lung (A549) and colon (HT-29) cell lines with $IC_{50}$ values of 8.2 and $5.6\;{\mu}M$ for 1; 5.1 and $1.8\;{\mu}M$ for 2, respectively.