RESUMEN

From the chloroform extract of the fresh fruits of Diospyros maritima BLUME (Ebenaceae), five new naphthoquinone derivatives, 2,7'-dimethyl-2',3-bijuglone (27), 2,7'-dimethyl-3,3'-bijuglone (28), 2,7'-dimethyl-6,8'-bijuglone (29), 7,7'-dimethyl-3,3'-ethylidenebijuglone (30), and 2',7-dimethyl-3,6'-ethylidenebijuglone (31), were isolated, in addition to twenty-one known naphthoquinone derivatives: plumbagin (4), droserone (5), 2,3-epoxyplumbagin (8), 3,3'-biplumbagin (9), chitranone (10), 3,8'-biplumbagin (11), elliptinone (12), maritinone (13), isozeylanone (14), methylene-3,3'-biplumbagin (15), ethylidene-3,3'-biplumbagin (16), ethylidene-3,6'-biplumbagin (17), ethylidene-6,6'-biplumbagin (18), 7-methyl-ß-dihydrojuglone (19), 7-methyljuglone (20), 2,3-epoxy-7-methyljuglone (21), neodiospyrin (22), mamegakinone (23), ehretione (24), isoxylospyrin (25) and ß-dihydroplumbagin (26). The structures of the new compounds were established by spectral analysis. The quinones obtained from the chloroform extract of the fruits were compared with previously reported quinones obtained from ethanol extracts. The quinones in the fruits were categorized in three groups: quinones from ethanol extract only, quinones from chloroform extract only, and quinones from both extracts. The six naphthoquinones, 19-21, 25, 26, and 29, were examined for their ichthyotoxic activity and germination inhibitory activity. Quinones 19-21, 26, and 29 showed ichthyotoxic activity against Japanese killifish (Oryzias latipes var.) at 10 ppm; quinones 19 to 21 and 26 showed germination inhibitory activity toward lettuce seeds (Lactuca sativa L. var. Great Lakes) at 100 ppm.

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RESUMEN

A polymer-supported terpyridine palladium complex was prepared. The complex was found to promote hydrodechlorination of aryl chlorides with potassium formate in seawater. Generally, reductive cleavage of aryl chlorides using transition metal catalysts is more difficult than that of aryl bromides and iodides (reactivity: I > Br > Cl); however, the results obtained did not follow the general trend. Therefore, we investigated the reaction inhibition agents and found a method to remove these inhibitors. The polymeric catalysts showed high catalytic activity and high reusability for transfer reduction in seawater.

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RESUMEN

The stepwise syntheses of germa[N]pericyclynes, including [5]pericyclynes, and their characterization are described. The yields of germa[4] and [8]pericyclynes were improved significantly compared to those obtained in previous studies. The routes reported herein afforded the novel germa[5] and [10]pericyclynes, which were characterized by X-ray crystallography, UV-Vis spectroscopy, and fluorescence emission spectroscopy. A unique fluorescence emission was observed for the large germa[10]pericyclyne ring.

RESUMEN

In the course of our study on the chemical and genetic diversity of the nudibranch Phylidiella pustulosa, we identified a series of isocyanosesquiterpenes. In addition to known sesquiterpenes, we isolated a new molecule 1, the structure of which was elucidated by analyzing NMR and other spectral data. We report the structure and cytotoxicity of compound 1 herein.

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RESUMEN

The synthesis and characterization of novel pericyclynes comprising germanium atoms and acetylenes, germa[n]pericyclynes, are described. The prepared germa[4]-, [6]-, and [8]pericyclynes were compared by (13)C NMR spectroscopy, X-ray crystallography, cyclic voltammetry, UV-visible spectroscopy, fluorescence emission spectroscopy, Raman spectroscopy, and density functional theory calculation analyses.

RESUMEN

Five new flavonoids, 5,8-dihydroxy-3,7-dimethoxy-3',4'-methylenedioxyflavone (1), 7-hydroxy-3,5-dimethoxy-3',4'-methylenedioxyflavone (2), 7-(2,3-dihydroxy-3-methylbutoxy)-3,5-dimethoxy-3',4'-methylenedioxyflavone (3), 7-(2,3-dihydroxy-3-methylbutoxy)-3,3',4',5-tetramethoxyflavone (4), and 7-(2,3-dihydroxy-3-methylbutoxy)-3,3',4',5,8-pentamethoxyflavone (5), were isolated from the leaves of Melicope triphylla. In addition, six known flavonoids were detected: 3,4',5-trihydroxy-3',7,8-trimethoxyflavone (6), 5,7-dihydroxy-3-methoxy-3',4'-methylenedioxyflavone (7), 4',5,7-trihydroxy-3,3'-dimethoxyflavone (8), 4',7-dihydroxy-3,3',5,8-tetramethoxyflavone (9), 4',7-dihydroxy-3,3',5-trimethoxyflavone (10), and 4',5,7-trihydroxy-3,3',8-trimethoxyflavone (11). The new compound structures were determined by spectroscopic methods. Compounds 1-5 did not exhibit any ichthyotoxic activity against Japanese killifish (medaka in Japanese) (Oryzias latipes var.) at 10 ppm.

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RESUMEN

Six new flavonoids--5-hydroxy-3,8-dimethoxy-3',4':6,7-bismethylenedioxyflavone (1), 3,3',4',5-tetramethoxy-7-(3-methylbut-2-enyloxy)flavone (2), 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,3',4',5-tetramethoxyflavone (3), 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,5-dimethoxy-3',4'-methylenedioxyflavone (4), 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,3',4',5,8-pentamethoxyflavone (5), and 7-(2-hydroxy-3-methylbut-3-enyloxy)-3,5,8-trimethoxy-3',4'-methylenedioxyflavone (6)--were isolated from the leaves of Melicope triphylla. In addition, six already known flavonoids were also detected: 5-hydroxy-3,6,7-trimethoxy-3',4'-methylenedioxyflavone (7), 5,7-dihydroxy-3,3',4',8-tetramethoxyflavone (8), 4',5-dihydroxy-3,3',7,8-tetramethoxyflavone (9), 3,5,6,7,8-pentamethoxy-3',4'-methylenedioxyflavone (10), 3,5,6,7-tetramethoxy-3',4'-methylenedioxyflavone (11), and 3,3',4',5,6,7,8-heptamethoxyflavone (12). The structures of the new compounds were established by spectroscopic methods. Compound 2 displayed ichthyotoxic activity against Japanese killifish (medaka in Japanese) (Oryzias latipes var.) at 10 ppm.

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Marine sponges have been recognized as potentially rich sources of various bioactive molecules. In our continuing search for new secondary metabolites from Indonesian marine invertebrates, we collected a sponge, whose extract showed cytotoxicity against cultured cells at 0.1 µg/mL. Purification of the extract yielded two new macrolides 2 and 3 along with known candidaspongiolide (1). The structures for compounds 2 and 3 were elucidated by spectral analysis ((1)H, (13)C, COSY, HMQC, HMBC) and by comparison of their NMR data with those of 1. Compounds 2 and 3 exhibited a little more potent cytotoxicity (IC(50) 4.7 and 19 ng/mL) than that (IC(50) 37 ng/mL) of candidaspongiolide (1) against NBT-T2 cells.

RESUMEN

Four new flavonoids, 3,5-dihydroxy-7,8-dimethoxy-3',4'-methylenedioxyflavone (1), 3,5-dihydroxy-7-methoxy-3',4'-methylenedioxyflavone (2), 3,5-dihydroxy-7-isopentenyloxy-8-methoxy-3',4'-methylenedioxyflavone (3) and 5-hydroxy-3-isopentenyloxy-7-methoxy-3',4'-methylenedioxyflavone (4), were isolated from the leaves of Melicope triphylla. In addition, two known flavonoids were detected including 5-hydroxy-3,7-dimethoxy-3',4'-methylenedioxyflavone (5) and 5-hydroxy-7-isopentenyloxy-3,8-dimethoxy-3',4'-methylenedioxyflavone (6). The structures of the new compounds were established by spectroscopic methods.

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RESUMEN

Nitromethane was safely applied as a C1 nucleophile for palladium-catalyzed pi-allylic substitution in water with amphiphilic PS-PEG resin-supported phosphine-palladium complexes. Catalytic asymmetric nitromethylation of cycloalkenyl esters was achieved in water as a single reaction medium under heterogeneous conditions using 5 mol % palladium of a PS-PEG resin-supported palladium-imidazoindolephosphine complex to give optically active (cycloalkenyl)nitromethanes with up to 98% ee.

RESUMEN

[reaction: see text] Rhodium-catalyzed asymmetric allylic alkylation of 1-substituted 2-propenyl acetates with dimethyl malonate proceeded with high enantioselectivity in the presence of cesium carbonate as a base and a rhodium catalyst generated from Rh(dpm)(C(2)H(4))(2) (dpm = dipivaloylmethanato) and a chiral phosphino-oxazoline whose basic skeleton is axially chiral binaphthyl to give branch alkylation products in greater than 90% ee.

RESUMEN

Enantioselective addition of aryllithiums 2a-d (Ar = Ph (a), 2-MeC(6)H(4) (b), 2-MeOC(6)H(4) (c), 1-naphthyl (d)) to 6-(dimethylamino)fulvene (1) in the presence of (-)-sparteine in toluene at -78 degrees C generated chiral cyclopentadienyllithiums (4) substituted with an N,N-dimethylamino(aryl)methyl group, where the enantioselectivities are 51, 91, 90, and 83% for 4a, 4b, 4c, and 4d, respectively. Treatment of the chiral cyclopentadienides 4 with FeCl(2) or Fe(acac)(2) gave ferrocenes, which contain an N,N-dimethylamino(aryl)methyl side chain on both of the cyclopentadienyl rings. The enantiomeric purity of the chiral ferrocenes 7 thus obtained is 99% ee or higher for those containing a 2-MeC(6)H(4) (7b) or a 2-MeOC(6)H(4) (7c) group.