Synthesis of Erythrochelin : A Hydroxamate-Type Siderophore from Saccharopolyspora erythraea

Erythrochelin, a hydroxamate-type siderophore produced by Saccharopolyspora erythraea, is synthesized for the first time. A key building block of erythrochelin containing the 2,5-diketopiperazine ring is prepared by intramolecular cyclization of the corresponding dipeptide precursor derived from two kinds of protected δ-N-hydroxy-L-ornithines. Consecutive condensation of the building block with protected D-serine and protected δ-N-hydroxy-D-ornithine, followed by deprotection, furnishes erythrochelin

Synthesis of Fluorine-Containing Analogues of 1-Lysoglycerophospholipids via Horner–Wadsworth–Emmons Reaction

This article describes an efficient method of synthesizing fluorine-containing analogues of 1-lysoglycerophospholipids (1-LPLs) by introducing a palmitoyl moiety starting from bis(2,2,2-trifluoroethyl)phosphonoacetate (Still-Gennari reagent). Our method effectively employs Horner-Wadsworth-Emmons reagents as masked 1-LPL derivatives to prepare a series of analogues of 1-lysophosphatidic acid (1-LPA), 1-lysophosphatidylethanolamine (1-LPE), and 1-lysophosphatidylcholine (1-LPC)

N4-methylation changes the conformation of (3S,6S)-3-alkyl-6-benzylpiperazine-2,5-diones from folded to extended

N4-Methylation of (3S,6S)-3-alkyl-6-benzylpiperazine-2,5-diones (S,S)-1a–c was found to change their folded conformation to an extended conformation. Conformational aspects of N1- and/or N4-methylated (S,S)-1a–c were revealed by single crystal X-ray crystallography and 1H NMR spectroscopy

Enzymatic synthesis of chiral P-stereogenic phosphonoacetates

In this data article, we describe the enzymatic kinetic resolution of a series of racemic mixed phosphonoacetates, which were successfully prepared from methyl bis(2,2,2-trifluoroethyl)phosphonoacetate (Still-Gennari reagent) by alcoholysis with σ-symmetrical secondary alcohols in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Porcine liver esterase (PLE)-catalyzed kinetic resolution of some of these racemic mixed phosphonoacetates proceeded in a highly stereoselective manner to furnish the chiral P-stereogenic phosphonoacetates (up to >99% ee)

Synthesis of Allenyl Esters by Horner-Wadsworth-Emmons Reactions of Ketenes Mediated by i-PrMgBr

The synthesis of conjugated allenyl esters (trisubstituted allenes) was achieved by the Mg(II)-mediated Horner-Wadsworth-Emmons reaction of methyl bis(2,2,2-trifluoroethyl)phosphonoacetate with di-substituted ketenes. In addition, a novel access to α-fluorinated allenyl carboxamides (tetra-substituted allenes) is presented

Continuous monitoring of groundwater radon for evaluating chemical and structural properties and fluid flow variations of shallow aquifer systems

We have carried out continuous monitoring of radon concentration in groundwater at eight wells in Nishinomiya City, Hyogo Prefecture, Japan. The shallowest major aquifer, which we call the first aquifer, extends widely at a depth about 3-5 meters in the region. We pay our major attention to the first aquifer, because it provides us with abundant high quality water, which has long been utilized for brewing Sake. We made the radon monitoring at 5 wells tapping the first aquifer. The first aquifer can be characterized by very high radon concentration and its large temporal variation. Time-averaged values of radon concentration at 4 shallow wells were about 70-80 Bq/l, which is almost the highest value ever reported for natural water throughout the Japanese Islands. These high radon concentrations can be attributed to uranium-rich sediments in the aquifer, which had been brought from the Rokko Mountains region on the north. Large temporal variations of radon concentration observed at the shallow wells probably reflect the heterogeneous distribution of the grain size of sediments, which makes the groundwater flow unstable. We examined radon concentrations in deeper aquifers at three wells with depths of 8-17 m for comparison. Absolute values of radon concentrations and their temporal variations at the deeper wells are smaller than those in the first aquifer, which suggests the small contributions of uranium-rich sands to the sediments compared with the first aquifer. The radon concentration at a well with a depth of 16 m showed periodical variations responding to the ocean tide, which demonstrates that very small signals of crustal deformations can be detected by the continuous monitoring of groundwater radon

Synthesis of Novel Phosphorus-Substituted Stable Isoindoles by a Three-Component Coupling Reaction of ortho-Phthalaldehyde, 9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-Oxide, and Primary Amines

A three-component coupling reaction of ortho-phthalaldehyde, 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide, and various primary amines readily afforded novel phosphorus-substituted stable isoindoles in good to excellent yields. The importance of the reversible ring-opening of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide by methanolysis in the three-component coupling reaction became apparent

Facile Two-Step Synthesis of Methyl Bis(2,2,2-trifluoroethyl)phosphonoacetate by Exploiting Garegg–Samuelsson Reaction Conditions

A facile two-step synthesis of methyl bis(2,2,2-trifluoroethyl)phosphonoacetate (Still–Gennari reagent) has been developed by exploiting Garegg–Samuelsson reaction conditions. Starting from trimethyl phosphonoacetate, Still–Gennari reagent was prepared in 94% yield via methyl 2-{bis[(trimethylsilyl)oxy]phosphoryl}acetate intermediate. This synthetic procedure was also used to prepare some kinds of Horner–Wadsworth–Emmons reagents and related compounds

Relationships between vegetation change and geomorphic conditions in suburban forests of Japan: Analysis by means of digital aerial photogrammetry and geographical information systems

金沢大学人間社会研究域人間科学系The relationships between successional vegetation change and geomorphic conditions were analyzed by using a high-resolution digital terrain model (DTM) and a time series of converted digital vegetation maps combined within a geographical information system (GIS). The results of the analysis confirmed that the pattern of vegetation change is a function of geomorphic conditions (measured in terms of spatio-statistical values of various parameters and time series of those values). Current geoecological studies are usually carried out by means of detailed field observations with high spatial resolution, and the results of our study suggest that a GIS can easily deal with such data over a large area and long time period. In the study area, unforested s ites were reforested using Japanese red pine (Pinus densiflora) as part of the forest rehabilitation work that occurred in the early 1950s. After that, two main patterns of vegetation change from pine forest to deciduous broadleaved forest occurred. In one type, the deciduous broadleaved forest reappeared quickly. In the other, the pine forests remained for a long time. Stands that underwent relatively rapid succession were found on north-facing gentle slopes close to large bodies of water. Stands that did not undergo rapid succession were found on steeper, warmer, and drier slopes (often south-facing slopes farther from bodies of water). The rate of forest succession towards deciduous broadleaved forest is a function of these geomorphic conditions. This suggests that forest succession is influenced by intermediate factors controlling by geomorphic conditions of site, such as soil moisture and soil thickness

Development of a novel tocopheryl ester for suppression of lipid accumulation without cytotoxicity by optimization of dicarboxylic ester moiety

Tocopheryl succinate (Tsuc) is a succinic acid ester of the well-known antioxidant α-tocopherol (T). Tsuc exhibits various biological activities, including tumor growth suppression via activation of cell signaling and prevention of lipid accumulation in mouse adipocyte 3T3-L1 cells. The latter findings suggest that Tsuc may be a drug candidate for the treatment of obesity. However, Tsuc was found to induce apoptosis of normal cells (in addition to cancer cells), demonstrating the need to reduce the cytotoxicity of Tsuc without losing the suppression effect on lipid accumulation. Based on our previous findings, we focused on the ester structure of Tsuc for controlling cytotoxicity. Herein, we examined the cytotoxicity and lipid accumulation suppression effect of various T ester derivatives. We found that the terminal carboxylic group is necessary for suppression of lipid accumulation. We synthesized tocopheryl glutarate (Tglu) and tocopheryl adipate (Tadi) by elongation of carbon atoms 1 and 2 of the dicarboxylic moiety, respectively. Tglu and Tadi did not show any cytotoxicity, and both esters suppressed lipid accumulation, although their suppression activities were weaker than that of Tsuc. Tadi showed a more potent lipid accumulation inhibitory effect than Tglu. Although Tadi inhibited lipogenesis and promoted lipolysis, lipolysis was induced at lower concentrations than inhibition of lipogenesis, suggesting that Tadi mainly affects lipolysis. Taken together, we succeeded in the reduction of cytotoxicity, without loss of the suppression effect on lipid accumulation, by elongation of the dicarboxylic moiety of Tsuc. Tadi may be a promising candidate as an anti-obesity drug