Ethyl 2-methylacetoacetate Research Articles

Synthesis, structural characterization, Hirshfeld surface, DFT calculation and antifungal activity of novel quinoline carbonothioate compounds

Three quinoline carbonothioate compounds were synthesized using o-fluoroaniline and ethyl 2-methylacetoacetate as starting materials via multi-steps. The structures of three compounds were confirmed using 1H NMR and HRMS. The structure of O-ethyl S-(8-fluoro-2,3-dimethylquinolin-4-yl) carbonothioate (3a) was further determined through X-ray single-crystal diffraction. Single-crystal X-ray diffraction analysis indicated that compound 3a crystallizes in the monoclinic space group C2/c, with unit cell parameters: a = 14.3284(6) Å, b = 19.2857(8) Å, c = 10.3990(5) Å, β = 108.1220(10)°, V = 2731.0(2) Å3. In addition, the physicochemical properties of compound 3a were calculated and discussed using molecular electrostatic potential, frontier molecular orbital and Hirshfeld surface analysis. The antifungal activity of the three compounds was evaluated at 50 μg/mL, with compound 3b exhibiting good activity (75.8%) against R. solani.

Synthesis, Structural Determination, and Antifungal Activity of Novel Fluorinated Quinoline Analogs.

A series of new fluorinated quinoline analogs were synthesized using Tebufloquin as the lead compound, 2-fluoroaniline, ethyl 2-methylacetoacetate, and substituted benzoic acid as raw materials. Their structures were confirmed by 1H NMR, 13C NMR, and HRMS. The compound 8-fluoro-2,3-dimethylquinolin-4-yl 4-(tert-butyl)benzoate (2b) was further determined by X-ray single-crystal diffraction. The antifungal activity was tested at 50 μg/mL, and the bioassay results showed that these quinoline derivatives had good antifungal activity. Among them, compounds 2b, 2e, 2f, 2k, and 2n exhibited good activity (>80%) against S. sclerotiorum, and compound 2g displayed good activity (80.8%) against R. solani.

Synthesis and study of the efficacies of Tetraaza macrocyclic ligand for the adsorption of heavy metals from wastewater

Condensation of Ethyl 2-methylacetoacetate and ethylenediamine yield 88.7% of Dimethyl-7,14-Diphenyl-1,4,8,11-Tetraazacyclotetradeca-4,7,11,14-Tetraene with a condense chemical formula as C 18 H 32 N 4 O 2 , and a molecular weight of 336.47. The complexes were prepared by the adsorption of heavy metals (Fe, Cu, Cd, Co and, Pb) from wastewater samples obtained from Kofar sauri, Lambun Dan Lawal and Youth craft village. The compounds were investigated by solubility, conductivity, melting/decomposition point, Atomic Absorption Spectroscopy, Infrared spectroscopy and Uv-visible spectroscopy. The Ligand 003 shows IR peak of υ(C=N) at 1633cm -1 , and a shift was observed to a lower peak as a result of adsorption of the heavy metals by the ligand, which is signifying the formation of the complexes. AAS results indicates high concentration of Cu in each case when compared, the rest of the metals varying at different level of concentration in the compounds. Cu may best fit the center of the ligand cavity having a concentration beyond computing with the rest of the metals. Key words : Schiff base, wastewater, heavy metals

Microbial Production of Chiral Hydroxy Esters and Their Analogs: Biocatalytic Reduction of Carbonyl Compounds by Actinobacteria, <i>Agromyces</i> and <i>Gordonia</i> Strains

We screened 15 Agromyces strains from the Microbacteriaceae family and 16 Gordonia strains from the Gordoniaceae family to investigate their biocatalytic ability to reduce carbonyl compounds. Two Agromyces strains (A. soli NBRC109063 and A. humatus NBRC109085) and two Gordonia strains (G. hydrophobica NBRC16057 and G. malaquae NBRC108250) grew well in 230 medium. The stereoselective reduction of various carbonyl compounds using these four strains was investigated. We discovered that these strains can reduce aliphatic and aromatic α-keto esters and an aromatic α-keto amide. On the basis of the conversion rate and stereoselectivity of the alcohols produced, G. hydrophobica NBRC16057 is a potential biocatalyst for the stereoselective reduction of α-keto esters and an aromatic α-keto amide to the corresponding chiral alcohols. Our results also suggest that the reduction of ethyl 2-methylacetoacetate by wet G. hydrophobica NBRC16057 cells in the presence of L-glutamate is useful for the production of chiral ethyl 3-hydroxy-2-methylbutanoate.

Effects of different algaecides on the photosynthetic capacity, cell integrity and microcystin-LR release of Microcystis aeruginosa

Bench scale tests were conducted to study the effects of four common algaecides, including copper sulfate, hydrogen peroxide, diuron and ethyl 2-methylacetoacetate (EMA) on the photosynthetic capacity, cell integrity and microcystin-LR (MC-LR) release of Microcystis aeruginosa. The release of potassium (K+) from cell membrane during algaecide exposure was also analyzed. The three typical photosynthetic parameters, including the effective quantum yield (Фe), photosynthetic efficiency (α) and maximal electron transport rate (rETRmax), were measured by a pulse amplitude modulated (PAM) fluorometry. Results showed that the photosynthetic capacity was all inhibited by the four algaecides, to different degrees, by limiting the energy capture in photosynthesis, and blocking the electron transfer chain in primary reaction. For example, at high diuron concentration (7.5mgL−1), Фe, α and rETRmax decreased from 0.46 to 0.19 (p<0.01), from 0.20 to 0.01 (p<0.01) μmol electrons m−2s−1/μmol photons m−2s−1, and from 160.7 to 0.1 (p<0.001) μmolm−2s−1 compared with the control group after 96h of exposure, respectively. Furthermore, the increase of algaecide dose could lead to the cell lysis, as well as release of intracellular MC-LR that enhanced the accumulation of extracellular MC-LR. The order of MC-LR release potential for the four algaecides was CuSO4>H2O2>diuron>EMA.

Effects of ethyl 2-methyl acetoacetate (EMA) on the growth of Phaeodactylum tricornutum and Skeletonema costatum

We investigated the effects of ethyl 2-methyl acetoacetate (EMA) on growth of the marine diatom algae Phaeodactylum tricornutum (P. tricornutum) and Skeletonema costatum (S. costatum). Growth of P. tricornutum was significantly inhibited by the minimum concentration (3.5 mmol·L −1) of EMA at lower initial algal densities (IADs) (3.6×104 and 3.3×105 cells·mL −1). However, at the highest IAD, significant growth inhibition was found at above 7 mmol·L −1 of EMA exposure. In S. costatum, EMA concentrations of 10.5 mmol·L −1 or more significantly inhibited growth at lower IAD (3×104 and 1.8×105 cells·mL −1); at the highest IAD, only EMA concentrations above 14 mmol·L −1 obviously inhibited the growth of S. costatum. Changes in specific growth rates and pigment were consistent with algal growth, but only at higher EMA concentrations or lower IAD values was the ratio of chlorophyll a (Chla) to carotenoid significantly lower than the control. Medium effective concentration (EC 50) values were in the order 4.07, 8.03 and 12.27 mmol·L −1 for P. tricornutum and 7.48, 11.92 and 17.22 mmol·L −1 for S. costatum. All these results show that the effect of EMA on the growth of algae was species specific and mainly depended on IAD, which might be an important factor to influence algal growth.

Ferric perchlorate-promoted reaction of [60]fullerene with β-keto esters

The ferric perchlorate-promoted reaction of [60]fullerene (C60) with ethyl 2-methylacetoacetate generates fullerenyl hemiketal as a mixture of trans and cis isomers, while the reaction with ethyl acetoacetate gives a C60-fused dihydrofuran derivative. A possible reaction mechanism for the formation of these products is proposed.

Allelochemical ethyl 2-methyl acetoacetate (EMA) induces oxidative damage and antioxidant responses in Phaeodactylum tricornutum

Ethyl 2-methyl acetoacetate (EMA) is a novel allelochemical exhibiting inhibitory effects on the growth of marine unicellular alga Phaeodactylum tricornutum ( P. tricornutum). Oxidative damage and antioxidant responses in P. tricornutum were investigated to elucidate the mechanism involved in EMA inhibition on algal growth. The increase in reactive oxygen species (ROS) levels and malondialdehyde (MDA) contents following exposure to EMA suggested that alga was suffered from oxidative stress and severely damaged. The decrease in cell activity and cellular inclusions suggested that cell growth was greatly inhibited. The activities of the antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxide (GSH-PX) and glutathione S-transferase (GST) increased with the exposure concentration and decreased with the prolongation of exposure time. Cellular ascorbic acid (AsA) and reduced glutathione (GSH) systems were also involved in resisting oxidative stress of EMA by altering the composition of AsA and GSH pools. EMA exposure increased the contents of AsA, GSH, dehydroascorbate (DAsA) and glutathione (GSSG). However, the regeneration rate of AsA/DAsA did not change obviously between treatments and the control, while that of GSH/GSSG decreased significantly under 14 mmol/L EMA exposure on the 3rd day. These results showed that EMA-induced oxidative damage might be responsible for EMA inhibition on P. tricornutum growth and cellular antioxidant enzymes and non-enzymatic antioxidants were improved to counteract the oxidative stress.

Enhancement effect of ethyl-2-methyl acetoacetate on triacylglycerols production by a freshwater microalga, Scenedesmus sp. LX1

Microalgae are very promising in biodiesel production. To reduce the production cost, approaches to enhance lipid and triacylglycerols (TAGs) production by microalgae have gained much attention. Effect of ethyl-2-methyl acetoacetate (EMA) on the lipid and TAGs production by a freshwater microalga, Scenedesmus sp. LX1, was studied in this paper. EMA below a concentration of 2 mg L(-1) had no significant effect on microalgal biomass or lipid production. The biomass and lipid productivity were about 0.47 g L(-1) and 139 mg L(-1), respectively, and the lipid content per biomass was about 30% (w/w). Promisingly, comparing with the one without EMA treatment, under EMA concentrations of 1.0-2.0 mg L(-1) the TAGs content per lipid (about 20% (w/w)) and TAGs productivity (about 23 mg L(-1)) were increased by 79% and 40%, respectively. Therefore, exposing algal cells with trace amount of EMA offers a viable method to enhance the TAGs production in Scenedesmus sp. LX1.

Effects of a Novel Allelochemical Ethyl 2-Methyl Acetoacetate (EMA) on the Ultrastructure and Pigment Composition of Cyanobacterium Microcystis aeruginosa

Allelochemical ethyl 2-methyl acetoacetate (EMA) can significantly inhibit the growth of bloom-forming Microcystis aeruginosa. In order to assess the implication of the damage of EMA on the algal photosynthetic apparatus, the effects of EMA on the algal ultrastructure and pigment composition were investigated. At initial exposure time to EMA (0-40 h), algal allophycocyanin, phycoerythrin and carotenoid degraded firstly; chlorophyll a increased, especially by 47% in the algae exposed to 2 mg L(-1) of EMA; phycocyanin was not significantly affected; lipid bodies increased remarkably. After 40 h of EMA exposure, chlorophyll a decreased gradually, especially by 45% in the algae exposed to 4 mg L(-1) of EMA; lipid bodies greatly reduced but cyanophycin granules accumulated; thylakoid structures were dissolved or disappeared with the presence of numerous vacuoles. These results showed that all ophycocyanin, phycoerythrin and carotenoid were more sensitive to EMA than other pigments, the cells of M. aeruginosa was stressed by EMA with the occurrence of cyanophycin granules and the photosynthesis pigments and ultrastructure of M. aeruginosa were quickly destroyed by EMA with exposure time increasing.

Responses of enzymatic antioxidants and non-enzymatic antioxidants in the cyanobacterium Microcystis aeruginosa to the allelochemical ethyl 2-methyl acetoacetate (EMA) isolated from reed ( Phragmites communis)

Macrophytic allelochemicals are considered an environment-friendly and promising alternative to control algal bloom. However, studies examining the potential mechanisms of inhibitory allelochemicals on algae are few. The allelochemical ethyl 2-methyl acetoacetate (EMA), isolated from reed (Phragmites communis), was a strong allelopathic inhibitor on the growth of Microcystis aeruginosa. EMA-induced antioxidant responses were investigated in the cyanobacterium M. aeruginosa to understand the mechanism of EMA inhibition on algal growth. The activities of enzymatic antioxidants superoxide dismutase (SOD) and catalase (CAT), and the contents of non-enzymatic antioxidants reduced glutathione (GSH) and ascorbic acid (AsA) of M. aeruginosa cells were analyzed after treatments with different concentrations of EMA. Exposure of M. aeruginosa to EMA caused changes in enzyme activities and contents of non-enzymatic antioxidants in different manners. The decrease in SOD activity occurred first after 4 h of EMA exposure, and more markedly after 40 h. CAT activity did not change after 4 h of EMA exposure, but increased obviously after 40 h. The contents of AsA and GSH were increased greatly by EMA after 4 h. After 60 h, low EMA concentrations still increased the CAT activity and the contents of AsA and GSH, but high EMA concentrations started to impose a marked suppression on them. EMA increased dehydroascorbate (DHAsA) and oxidized glutathione (GSSG) contents during all exposure times. After 60 h, the regeneration rates of AsA and GSH (represented by the AsA/DHAsA ratio and GSH/GSSG ratio, respectively) were reduced by high EMA concentrations. These results suggest that the activation of CAT and the availability of AsA and GSH at early exposure are important to counteract the oxidative stress induced by EMA, and the inactivation of SOD may be crucial to the growth inhibition of M. aeruginosa by EMA.

Growth and physiological responses of freshwater green alga Selenastrum capricornutum to allelochemical ethyl 2-methyl acetoacetate (EMA) under different initial algal densities

Most natural algicides including macrophytic allelochemicals are known to selectively inhibit algal growth. The investigations on the modes of action about the species-specific algicides are little. In this study, the effects of allelochemical ethyl 2-methyl acetoacetate (EMA) identified from reed ( Phragmites communis) on the growth, physiological, and biochemical processes of green alga Selenastrum capricornutum were investigated. The results showed that EMA had multiple effects on the growth of S. capricornutum under different initial algal densities (IADs). The algal growth was inhibited by EMA at low IADs, but stimulated at high IADs. Further, the potential modes of action of EMA on S. capricornutum were explored from ultrastructure, metabolic activity, reactive oxygen species level, and lipid peroxidation to trace the microenvironment changes in the algal cells. Damage in cell structure occurred at low IAD, but cells were well developed with increased metabolic activity at high IAD. The reactive oxygen species (ROS) levels were increased under both conditions. The increase of ROS level was acute at low IAD but slow at high IAD. EMA caused significant lipid peroxidation, i.e. oxidative damage on membrane lipids at low IAD but not at high IAD. Based on these results, the initial algal density is considered an important factor to influence algal growth and physiological and biochemical responses to EMA, the effects of EMA on S. capricornutum may be “hormesis-like”, and different ROS increase ratio may be directly related with different responses of S. capricornutum to EMA.

Physiological and biochemical effects of allelochemical ethyl 2-methyl acetoacetate (EMA) on cyanobacterium Microcystis aeruginosa

The physiological and biochemical effects of an allelochemical ethyl 2-methyl acetoacetate (EMA) isolated from reed ( Phragmites communis) on bloom-forming cyanobacterium, Microcystis aeruginosa, were investigated. EMA significantly inhibited the growth of M. aeruginosa in a concentration-dependent way. The metabolic indices (represented by esterase and total dehydrogenase activities), the cellular redox status (represented by the level of reactive oxygen species (ROS)), and the oxidative damage index (represented by the content of malondialdehyde (MDA), the product of membrane lipid peroxidation) were used to evaluate the physiological and biochemical changes in M. aeruginosa after EMA exposure. Esterase activity in M. aeruginosa did not change ( P>0.05) after 2 h of exposure to EMA, but increased greatly after 24 and 48 h ( P<0.05). EMA exposure (>0.5 mg L −1) resulted in a remarkable loss of total dehydrogenase activity in M. aeruginosa after 4 h ( P<0.01), but an increase after 40 h ( P<0.05). EMA caused a great increase in ROS level of the algal cells. At high EMA concentration (4 mg L −1), the ROS level was remarkably elevated to 1.91 times as much as that in the controls after 2 h. Increases in the ROS level also occurred after 24 and 48 h. The increase in lipid peroxidation of M. aeruginosa was dependent upon EMA concentration and the exposure time. After 40 h of exposure, the MDA content at 4 mg L −1 of EMA reached approximately 3.5 times ( P<0.01) versus the controls. These results suggest that the cellular structure and metabolic activity of M. aeruginosa are influenced by EMA; the increased metabolic activity perhaps reflects the fact that the resistance of cellular response system to the stress from EMA is initiated during EMA exposure, and the oxidative damage induced by EMA via the oxidation of ROS may be an important factor responsible for the inhibition of EMA on the growth of M. aeruginosa.

Stereochemical Consequences of Threefold Symmetry in Asymmetric Catalysis: Distorting C3 Chiral 1,1,1‐Tris(oxazolinyl)ethanes (“Trisox”) in CuII Lewis Acid Catalysts

The underlying conceptual differences in exploiting two- and threefold rotational symmetry in the design of chiral ligands for asymmetric catalysis have been addressed in a comparative study of the catalytic performance of bisoxazoline (BOX) and tris(oxazolinyl)ethanes (trisox) containing copper(II) Lewis acid catalysts. The differences become apparent in constructing new catalysts by systematically "deforming" the stereodirecting ligand by inverting chiral centres or replacing chiral by achiral oxazolines. The catalytic alpha-amination of ethyl 2-methylacetoacetate with dibenzyl azodicaboxylate, which occurs with high enantioselectivity for both Ph(2)-BOX and Ph(3)-trisox copper catalysts, has been employed as the test reaction. In the trisox-copper complex [Cu(II)(iPr(3)-trisox)(kappa(2)-O,O'-MeCOCHCOOEt)](+)[BF(4)](-) (1), which was characterised by X-ray diffraction, two of the oxazoline groups are coordinated to the central copper atom, whilst the third oxazoline unit is dangling with the N-donor pointing away from the metal centre. A similar arrangement is found for the stereochemically "mixed" C(1)-trisox complex [Cu(II){(Ph(3)-trisox(R,S,S)}(kappa(2)-O,O'-MeCOCHCOOEt)(H(2)O)](+)[ClO(4)](-) (2), in which the phenyl substituents adopt a first coordination sphere meso arrangement. The almost identical selectivity of the Ph(3)-trisox(R,R,R)- and Ph(2)-BOX(R,R)-derived catalysts is as expected from the proposed model of the active catalyst based on a partially decoordinated podand. The behaviour of the "desymmetrised" trisox-Cu catalysts may be rationalised in terms of a general steady-state kinetic model for the three possible active bisoxazoline-copper species, which are expected to be in rapid exchange with each other in solution. This applies to both the trisox derivatives with stereochemically inverted and achiral oxazoline rings. The study underscores previous observations of superior performance of the catalysts bearing C(3)-chiral stereodirecting ligands as compared to systems of lower symmetry.

Effects of the novel allelochemical ethyl 2-methylacetoacetate from the reed (Phragmitis australis Trin) on the growth of several common species of green algae

Bioassays were performed to investigate the effects of the novel allelochemical, ethyl 2-methylacetoacetate (EMA), isolated from the reed (Phragmitis australis) on the growth of three common species of algae; Scenedesmus obliquus, Selenastrum capricornutum and Chlamydomonas reinhardtii. The results demonstrated that EMA has three quite different types of effect on these three species of algae. The growth of S. capricornutum was significantly inhibited by EMA during the whole cultivation period. The EC50 values of EMA on S. capricornutum was 0.6 mg L−1(7 days). However, the inhibitory effect of EMA on S. obliquus was apparent during the first 4 days of batch cultivation and then the inhibitory effect disappeared, and a stimulating effect was observed instead. The EC50 value of EMA on S. obliquus was 0.43 mg L−1(4 days). In addition, following the addition of EMA, the cells of S. obliquus and S. capricornutum became significantly larger than the normal untreated one and the algal cells changed morphologically. The microstructure of the algal cells was disrupted by the addition of EMA. There was no significant inhibition of the growth of C. reinhardtii by EMA, but cell motility was affected.

Isolation and Characterization of a Novel Antialgal Allelochemical from Phragmites communis

Antialgal allelochemicals were isolated from Phragmites communis Tris. The isolated allelopathic fraction showed strong inhibition activity on the growth of Chlorella pyrenoidosa and Microcystis aeruginosa but had no inhibition on Chlorella vulgaris. The 50% effective concentrations (EC50) of the allelopathic fractions on C. pyrenoidosa and M. aeruginosa were 0.49 and 0.79 mg/liter, respectively. The allelopathic activity of the fraction was species-specific. The isolated allelopathic fraction caused metal ion leakage from algal cells. The fraction decreased the activities of antioxidant enzymes, such as superoxide dismutase and peroxidase. The addition of the isolated fraction increased the concentration of unsaturated lipid fatty acids in cell membrane of C. pyrenoidosa and M. aeruginosa. This caused a change in plasma membrane integrity and the leakage of ions in the protoplast. The allelopathic compound was identified by nuclear magnetic resonance and gas chromatography-mass spectrometry as ethyl 2-methylacetoacetate. Synthesized ethyl 2-methylacetoacetate also showed allelopathic activity on C. pyrenoidosa and M. aeruginosa. The EC50 of synthesized ethyl 2-methylacetoacetate on C. pyrenoidosa and M. aeruginosa were 0.49 and 0.65 mg/liter, respectively.

(E)-6-(2,2,3-Trimethyl-cyclopent-3-enyl)-hex-4-en-3-one

Ethyl 2-methylacetoacetate (2) (727 mg, 4.53 mmol) was added to a stirred solution of NaH (184 mg, 4.60 mmol) in dioxane (25 mL).[...]

Rhenium(I)-Induced Cyclization of Thiosemicarbazones Derived from β-Keto Esters

The reactions of methylacetoacetate and ethyl 2-methylacetoacetate thiosemicarbazones (H(2)L(A) and H(2)L(B), respectively) with [ReX(CO)(5)] and [ReX(CO)(3)(CH(3)CN)(2)] (X = Cl, Br) were explored under various experimental conditions. Besides the adducts fac-[ReX(CO)(3)(H(2)L)], in which the rhenium is coordinated to three carbonyl groups, the X anion, and the N,S-bidentate thiosemicarbazone ligand, the following complexes were also isolated: fac-[ReBr(CO)(3)(Hpyz(B))], the tetrameric complexes fac-[Re(pyz(A))(CO)(3)](4) and fac-[Re(pyz(B))(CO)(3)](4), and fac-[Re(pyz(B))(CO)(3)(H(2)O)] (where Hpyz(A) and Hpyz(B) are pyrazolones derived by cyclization of H(2)L(A) and H(2)L(B), respectively). The cyclization reactions were monitored by (1)H NMR spectroscopy and the complexes isolated were identified by elemental analysis, mass spectrometry, IR and (1)H NMR spectroscopy, and in some cases by X-ray diffractometry. The isolation and the full structural identification of the rather unusual fac-[ReBr(CO)(3)(Hpyz(B))], which contains the enol form of the pyrazolone ligand, affords new insight into the cyclization of thiosemicarbazones derived from beta-keto esters.

Metal-induced cyclization of thiosemicarbazones derived from beta-keto amides and beta-keto esters: open-chain and cyclized ligands in zinc(II) complexes.

The reactions of Zn(OAc)(2) with acetoacetanilide, methyl acetoacetate, o-acetoacetanisidide, and ethyl 2-methylacetoacetate thiosemicarbazones (HTSC(1), HTSC(2), HTSC(3), and HTSC(4), respectively) were explored in methanol. With HTSC(1), HTSC(2), and HTSC(3), following isolation of the corresponding zinc(II) thiosemicarbazonates [Zn(TSC(x))(2)] (x = 1, 2, 3), the mother liquors afforded pyrazolonate complexes [ZnL(1)(2)(H(2)O)] (HL(1) = 2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothioamide) that had been formed by cyclization of the corresponding TSC(-). The reaction of HTSC(4) with zinc(II) acetate gave only the pyrazolonate complex [ZnL(2)(2)(H(2)O)] (HL(2) = 2,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazole-1-carbothioamide). All compounds were studied by IR and NMR spectroscopy, and HTSC(3), [Zn(TSC(3))(2)] x DMSO, [ZnL(1)(2)(H(2)O)] x 2DMSO, and [ZnL(2)(2)(H(2)O)] x 2DMSO were also studied by X-ray diffractometry, giving a thorough picture of the cyclization process. In preliminary tests of the effects of HL(1) and [ZnL(1)(2)(H(2)O)] on rat paw inflammatory edema induced by carrageenan, HL(1) showed antiinflammatory activity.

A Practical Synthesis of (2S,3R,4S)-4-Hydroxyisoleucine, A Potent Insulinotropic α-Amino Acid from Fenugreek

An efficient eight-step synthesis of optically pure (2S,3R,4S)-4-hydroxyisoleucine (1), a potent insulinotropic α-amino acid found in the seeds of fenugreek (Trigonella foenum-graecum L.), is achieved in 39% overall yield. The method is suitable for large-scale production of the title compound. The key steps involve the biotransformation of ethyl 2-methylacetoacetate to ethyl (2S,3S)-2-methyl-3-hydroxybutanoate (2) with Geotrichum candidum and an asymmetric Strecker synthesis. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)