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A simple and convenient approach for highly enantioenriched 2-substituted 1,4-benzothiazin-3-ones was developed via the nucleophilic substitution of α-bromoacetates derived from either l-threonate or l-serinate using 2-aminothiophenol and a subsequent facile lactamization.

A novel synthetic strategy for highly enantioenriched cis-3,5-disubstituted γ-lactones has been developed by the AgOTf-promoted nucleophilic substitution of α-bromoacetates with silyl enol ethers and subsequent reductive lactonization. The utility of this synthetic method was further demonstrated through the concise stereodivergent synthesis of cis- and trans-2,4-disubstituted tetrahydrofurans.

Individual differences in ginsenoside pharmacokinetics following ginseng administration in humans are still unclear. We aimed to investigate the pharmacokinetic properties of various ginsenosides, including Rb1, Rg3, Rg5, Rk1, F2, and compound K (CK), after a single oral administration of red ginseng (RG) and bioconverted red ginseng extract (BRG). This was a randomized, open-label, single-dose, single-sequence crossover study with washout every 1 week, and 14 healthy Korean men were enrolled. All subjects were equally assigned to two groups and given RG or BRG capsules. The pharmacokinetic parameters of ginsenosides were measured from the plasma drug concentration–time curve of individual subjects. Ginsenosides Rg3, Rk1 + Rg5, F2, and CK in the BRG group showed a higher Cmax, AUC(0–t), and AUC(0–∞) and shorter Tmax (for CK) than those in the RG group. These results suggest that BRG may lead to a higher absorption rate of bioactive ginsenosides. This study provides valuable information on the pharmacokinetics of various bioactive ginsenosides, which is needed to enhance the therapeutic efficacy and pharmacological activity of ginseng.

A novel synthetic strategy for highly enantioenriched

A novel one-pot asymmetric synthetic method for the direct conversion of bromoacetates into highly substituted hydantoins has been developed. Both enantiomers of 1,3,5-trisubstituted hydantoins were conveniently synthesized through a dynamic kinetic resolution of bromoacetates derived from either ethyl l-lactate or diacetone-d-glucose. The sequential three-component reaction permitted the preparation of (R)- or (S)-1,3,5-trisubstituted hydantoins in yields of 77–51% with enantiomeric ratios of up to 95:5.

Seoul National University Radio Astronomy Observatory (SRAO), a 6-meter single-dish telescope recently applied new 100GHz and 230GHz dual-band receiver. The SRAO had been inactive for several years, but resumed operation by adapting the Combined Array for Research in Millimeter-wave Astronomy (CARMA) receiver. We succeeded in the single-dish observations in 2019 March. We upgraded the SRAO to the mm-VLBI station and participated in the test observation of East Asia VLBI Network (EAVN) with several telescopes worldwide. The simultaneous single dish and VLBI observation is possible. We are going to design the new receiver and import a wideband 230GHz mixer and have a VLBI observation with Korean VLBI Network (KVN). Also, we are planning to test the phase reference technique between 100Ghz and 230GHz.

Nickel nanoparticles supported on a NiO-MgO solid solution are fabricated using the exsolution process. Upon reduction, the nickel nanoparticles are exsoluted from a Ni0·4Mg0·6O solid solution powder. From the results obtained from transition electron microscopy (TEM) and temperature programmed reduction (TPR) measurements, it is concluded that the size and dispersion state of the nickel nanoparticles strongly depend on the homogeneity of the parent solid solution. Sintering the parent solid solution powder at a high temperature results in a homogeneous solid solution, which leads to a decreased reducibility of the nickel ions and, consequently, well-distributed Ni nanoparticles are successfully obtained. The metallic nickel moves reversibly to and out of the parent solid solution in response to a specific atmospheric condition. The methane steam reforming over the as-synthesized nickel nanoparticles are evaluated and appreciable degradation (1000 h) of the catalytic activity is not found for the catalyst sample that is sintered at 1000 °C followed by subsequent reduction to 800 °C.

We present a performance test of the point-spread function (PSF) deconvolution algorithm applied to astronomical integral field unit (IFU) spectroscopy data for restoration of galaxy kinematics. We deconvolve the IFU data by applying the Lucy–Richardson algorithm to the 2D image slice at each wavelength. We demonstrate that the algorithm can effectively recover the true stellar kinematics of the galaxy, by using mock IFU data with a diverse combination of surface brightness profile, signal-to-noise ratio, line-of-sight geometry, and line-of-sight velocity distribution (LOSVD). In addition, we show that the proxy of the spin parameter λ R e can be accurately measured from the deconvolved IFU data. We apply the deconvolution algorithm to the actual SDSS-IV MaNGA IFU survey data. The 2D LOSVD, geometry, and λ R e measured from the deconvolved MaNGA IFU data exhibit noticeable differences compared to the ones measured from the original IFU data. The method can be applied to any other regular-grid IFU data to extract the PSF-deconvolved spatial information.

Although self-assembly of various peptides has been widely applied, it is challenging to obtain single-crystalline and layer-by-layered nanostructures in a two-dimensional system. Here, we report a method for controlling the morphology and crystal growth at room temperature by a redox-active peptide template that can specifically co-assemble with metal ions. During the crystal growth, a silver ion-coordinated α-helical peptide (+3HN-YYACAYY-COO-) induces long-range atomic ordering at the air/water interface, which leads to multilayered single-crystalline silver nanosheets without an additional annealing process. Furthermore, this peptide template can facilitate efficient electron transfer between the independent metal nanosheets to improve electrochemical properties. We expect that this peptide template-based single-crystal growth method can be extended to synthesize other materials.

Highly enantioenriched 2,2-diarylethanols can be efficiently synthesized through the Friedel–Crafts alkylation of (hetero)arenes with configurationally labile α-bromoarylacetates. The substitution of highly diastereoenriched α-bromoarylacetates occurs in the presence of AgOTf, and the subsequent reduction affords diverse 2,2-diarylethanols with high yields and enantioselectivities up to 99 : 1 er. In addition, the application of this asymmetric synthetic methodology to the preparation of highly enantioenriched dihydrobenzofuran and indoline derivatives is demonstrated.

Piscidin 1 (Pis-1) from hybrid striped bass possesses antibacterial activities with high cytotoxicity. Previously, we reported that Pis-1[NkG], where Gly8 was substituted with positively charged Lys peptoid in Pis-1, shows high antibacterial activity with more potent bacterial cell selectivity than parent Pis-1 and Pis-1[PG] with Pro substitution at Gly8. Here, we investigated the effects of hydrophobic peptoid substitutions on antimicrobial activity and cytotoxicity of Pis-1. We designed Pis-1[NaG] and Pis-1[NlG] peptides, where Gly8 was replaced with alanine or leucine peptoids. Although hydrophobicity was increased in Pis-1[NaG] and Pis-1[NlG] compared with that in Pis-1[NkG], Pis-1, and Pis-1[PG], these peptides retained high antibacterial activity and showed no hemolytic activity when used at 100 μM. All peptoid-substituted peptides penetrated well the bacterial membrane and localized inside of the cytoplasm, while Pis-1 and Pis-1[PG] depolarized membrane severely. The flexible hinge structure formed by peptoid residues compared with the rigid bent structure formed by proline may explain their differential mechanisms of action. Most hydrophobic peptide, Pis-1[NlG], showed the most efficient inhibition of LPS (lipopolysaccharide)-induced nitric oxide production, indicating that it can be a potent antimicrobial peptide with anti-inflammatory activities. Peptoid substitution may facilitate the development of potent peptide drugs with bacterial cell selectivity.

We developed a highly stereoselective C–N and C–C bond-forming reaction by carrying out a crystallization-induced dynamic resolution (CIDR) of α-bromo arylacetates followed by a stereoselective substitution reaction with an amine or azlactone nucleophile. Applications of this synthetic method to the preparation of highly enantioenriched nitrogen-containing six-membered heterocycles and α,β-disubstituted aspartates are also presented.

On July 1 2012, the carriage requirement for ECDIS became mandatory in a phased-in manner. The system has since been widely used as a core bridge navigation system and as a replacement for paper charts with a back up arrangement. However operational anomalies have been found in the system internationally. IMO and IHO have recognised these anomalies and seek for solution. This study has been conducted on a survey of seafarers on the use of ECDIS with regard to anomalies identification, level of the seafarer satisfaction and requirements for further functional improvement. From the results, the ECDIS user focused requirements suggested on strengthening the level of navigational safety and efficiency. The efficiency of using main functions of ECDIS was positively evaluated. However, there were concerns regarding its operational safety.

A novel methodology for the asymmetric synthesis of trans-3,4-diaryl-substituted tetrahydroquinolines via sparteine-assisted stereoselective lithiation of o-substituted N-pivaloylanilines (I), kinetic resolution of epoxides in substitution and a stereospecific Mitsunobu cyclization is developed.

Devasthal Optical Telescope Integral Field Spectrograph (DOTIFS) is a new multi-Integral Field Unit (IFU) instrument, planned to be mounted on the 3.6m Devasthal optical telescope in Nainital, India. It has eight identical, fiber-fed spectrographs to disperse light coming from 16 IFUs. The spectrographs produce 2,304 spectra over a 370-740nm wavelength range simultaneously with a spectral resolution of R=1200-2400. It is composed of all-refractive, all spherical optics designed to achieve on average 26.0% throughput from the telescope to the CCD with the help of high transmission spectrograph optics, volume phase holographic grating, and graded coated e2v 2K by 4K CCD. We present the optical and opto-mechanical design of the spectrograph as well as current development status. Optics and optomechanical components for the spectrographs are being fabricated., Comment: 14 pages, 10 figures, Conference poster at SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

We report simultaneous single-dish surveys of 22 GHz H2O and 44 and 95 GHz class I CH3OH masers toward 299 Red MSX Sources in the protostellar stage. The detection rates are 45% at 22 GHz, 28% at 44 GHz, and 23% at 95 GHz. There are 15, 53, and 51 new discoveries at 22, 44, and 95 GHz, respectively. We detect high-velocity (>30 km/s) features in 27 H2O maser sources. The 95 GHz maser emission is detected only in 44 GHz maser sources. The two transitions show strong correlations in the peak velocity, peak flux density, and isotropic maser luminosity, indicating that they are likely generated in the same sites by the same mechanisms. The 44 GHz masers have much narrower distributions than 22 GHz masers in the relative peak velocity and velocity range, while 6.7 GHz class II CH3OH masers have distributions intermediate between the two. The maser luminosity significantly correlates with the parental clump mass, while it correlates well with the bolometric luminosity of the central protostar only when data of the low-mass regime from the literature are added. Comparison with the results of previous maser surveys toward massive star-forming regions suggests that the detection rates of 22 and 44 GHz masers tend to increase as the central objects evolve. This is contrary to the trends found in low- and intermediate-mass star-forming regions. Thus the occurrence of both masers might depend on the surrounding environments as well as on the evolution of the central object., 65 pages, 18 figures, 6 tables, accepted for publication in ApJS

Both enantiomers of N-substituted 3-arylated 3,4-dihydro-1,4-benzoxazin-2-ones were conveniently synthesized up to 93:7 er based on the dynamic kinetic resolution of either (R)-pantolactone- or l-mandelate-derived α-bromo arylacetates in nucleophilic substitution with N-alkylated 2-aminophenols.

A rapid, sensitive and specific method was developed and validated using electrospray ionization (ESI) tandem mass spectrometry (LC-MS/MS) for determination of misoprostol acid in human plasma. Misoprostol acid-d5 was used as in internal standard (IS). The analyte and IS were extracted by simple one step solid phase extraction (SPE). Linearity in plasma was obtained over the concentration range 10~3000 pg/mL and lower limit of quantification (LLOQ) was identifiable and reproducible at 10 pg/mL. The intraand inter-day precision values were below 9% and the accuracy was ranged from 93.81% to 102.02% at all four quality control samples. The method was has been successfully applied for routine assay to support pharmacokinetic study of misoprostol acid in human plasma after an oral administration of 0.4 mg misoprostol.

A specifically designed peptide, Tyr-Tyr-Ala-His-Ala-Tyr-Tyr (YYAHAYY), induced the formation of a flower-like palladium (Pd) nanostructure by controlling the size and shape of nanoparticles (NPs). The flower-shaped Pd NPs showed excellent catalytic activities in copper-free Sonogashira cross-coupling reaction in water.

A novel asymmetric synthetic strategy to prepare 4-aryl-dihydroisoquinolinones has been developed through a highly regioselective Friedel-Crafts alkylation of benzylamine derivatives with (αR)-α-bromo arylacetates and subsequent facile lactamization. In addition, an efficient asymmetric synthesis of 2-aryl morpholinones is demonstrated with 2-aminoethanol derivatives using the same convenient substitution-lactamization protocol.

We report the development of solar flux receivers operating at 2.8 GHz to monitor solar radio activity. Radio waves from the sun are amplified, filtered, and then transmitted to a power meter sensor without frequency down-conversion. To measure solar flux, a calibration scheme is designed with a noise source, an ambient load, and a hot load at 100 ℃. The receiver is attached to a 1.8 m parabolic antenna in Icheon, owned by National Radio Research Agency, and observation is being conducted during day time on a daily basis. We compare the solar fluxes measured for last seven months with solar fluxes obtained by DRAO in Penticton, Canada, and by the Hiraiso solar observatory in Japan, and finally establish equations to convert observed flux to the so-called Penticton flux with an accuracy better than 3.2 sfu.

Intensity interferometry, based on the Hanbury Brown-Twiss effect, is a simple and inexpensive method for optical interferometry at microarcsecond angular resolutions; its use in astronomy was abandoned in the 1970s because of low sensitivity. Motivated by recent technical developments, we argue that the sensitivity of large modern intensity interferometers can be improved by factors up to approximately 25,000, corresponding to 11 photometric magnitudes, compared to the pioneering Narrabri Stellar Interferometer. This is made possible by (i) using avalanche photodiodes (APD) as light detectors, (ii) distributing the light received from the source over multiple independent spectral channels, and (iii) use of arrays composed of multiple large light collectors. Our approach permits the construction of large (with baselines ranging from few kilometers to intercontinental distances) optical interferometers at the cost of (very) long-baseline radio interferometers. Realistic intensity interferometer designs are able to achieve limiting R-band magnitudes as good as ~14, sufficient for spatially resolved observations of main-sequence O-type stars in the Magellanic Clouds. Multi-channel intensity interferometers can address a wide variety of science cases: (i) linear radii, effective temperatures, and luminosities of stars; (ii) mass-radius relationships of compact stellar remnants; (iii) stellar rotation; (iv) stellar convection and the interaction of stellar photospheres and magnetic fields; (v) the structure and evolution of multiple stars; (vi) direct measurements of interstellar distances; (vii) the physics of gas accretion onto supermassive black holes; and (viii) calibration of amplitude interferometers by providing a sample of calibrator stars., Comment: 19 pages, 4 figures, 3 tables; to appear in JKAS (received June 11, 2014; accepted October 18, 2014)

We study the physical and chemical properties of the molecular clump hosting a young stellar cluster, IRAS 20160+3636, which is believed to have formed via the “collect and collapse” process. Physical parameters of the UC Hii region associated with the embedded cluster are measured from the radio continuum observations. This source is found to be a typical Galactic UC Hii region, with a B0.5 type exciting star, if it is ionized by a single star. We derive a CN/HCN abundance ratio larger than 1 over this region, which may suggest that this clump is being affected by the UV radiation from the Hii region.

>> The sensing of a stack coolant deficiency is very important in that cooling performance of a fuelcell, overheating prevention of a stack or coolant heater. This paper explains the performance comparison betweenthe coolant contact/noncontact level sensors and coolant deficiency sensing logic using the pressure sensor in astagnant or circulating flow. Throughout the comparison, the pressure sensor is more suitable than the other sensorsin terms of the precision, fast response, sensing frequency. After the experiment, the pressure sensor is equippedto an FCEV(Fuel Cell Electric Vehicle) to verify sensing definitely. There was no miss-sensing using pressure sensor while FCEV runs in the conditions of the paved road and cross country road. Key words : Coolant Deficiency(냉각수 부족), Level Sensor(수위센서), Parameter Tuning(매개변수 조정), Coolant Deficiency Sensing Logic(냉각수 부족 감지 로직), Pressure Sensor(압력 센서), Stack Coolant (스택 냉각수) † Corresponding author : hyungkook@hyundai.com [ 접수일 : 2014.08.01 수정일 : 2014.10.02 게재확정일 : 2014.10.31 ]Copyright ⓒ 2014 KHNES

>> Proper discharge of nitrogen gas and water condensate is required in a conventional fuel cell systemfor performance, stability and durability of fuel cell stacks. Present study covers the development of integratedunit and its functioning logic for simultaneous nitrogen gas purge and water condensate drainage in a fuel cellvehicle system. Configuration of condensate drainage pipe, purge valve and level sensor is considered and optimizedin physical integration. As a key factor, discharge time is considered and optimized based on the test result ofconstant-current operation with various operating temperature in logic development. Consequently, derived optimalvalues are applied and verified in actual vehicle drive mode test.Increase of system design flexibility, weight reduction and cost reduction are anticipated with this study. Additional study for physical and logical improvement is currently being implemented. Key words : Nitrogen purge(질소 배출), Condensate drainage(응축수 배출), Electrochemical reaction(전기화학반응), Fuel cell(연료전지), Constant-current driving test(정전류 운전 시험)

At the fuel processing system (FPS) of fuel cell vehicle, hydrogen recirculation blower (HRB) is used for the recirculation of remained hydrogen after reaction. In this paper, noise and vibration improvement of HRB is studied by changing design and control. It is checked the campbell diagram and critical speed for stability of rotor, and housing stiffness is improved using simulation of frequency response function (FRF). A method is suggested that can decrease the unbalance amount of the rotor and impeller which main source of noise and vibration. In order to reduce the noise during deceleration of blower, electrical braking is applied and tested the risk impact of durability. Founded the optimum switching frequency of the motor control, and reduced the idle rpm by increasing of aerodynamic performance. The superiority of paper is proved by measurement of the improved product's noise and vibration.

The (+)-sparteine-mediated lithiation–substitution of o-benzyl-N-pivaloylaniline with various ketones was investigated. The obtained highly enantioenriched tertiary alcohols were used for the synthesis of alkenyl-substituted products 12 and 13 as well as 3,3,4-trisubstituted tetrahydroquinoline derivatives 22–24. The reaction with α,β-unsaturated ketones afforded highly enantioenriched 1,4-addition products 28–33 and provided a protocol for the asymmetric synthesis of highly substituted tetralin derivative 34.

A new and efficient method for the asymmetric synthesis of 3,4,6-trisubstituted 2,5-diketopiperazines has been developed. The dynamic kinetic resolution of L-amino-acid-derived α-bromo tertiary amides in the nucleophilic substitution reaction with p-anisidine and a subsequent deprotection-cyclization process provides rapid access to diverse cis-2,5-diketopiperazines 5a–5o and proline-containing trans-2,5-diketopiperazines 5p–5t in enantiomerically pure form in 45–67 % overall yields.

Many chiral alcohols have successfully been used as a chiral auxiliary for the dynamic resolution of -halo esters in nucleophilic substitution. 1 L-Threonine is a proteinogenic -amino acid that bears a chiral alcohol group. However, so far L-threonine has not been used as a chiral auxiliary for the dynamic resolution of -halo esters. We herein report the first example of L-threonine-mediated dynamic kinetic resolution of -bromo esters in nucleophilic substitution with various amine nucleophiles. Treatment of N-acetyl L-threonine isopropyl ester with racemic -bromo phenylacetic acid in the presence of dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) provided -bromo ester (RS)-1 in 70% yield with about 50:50 diastereomeric ratio (dr). When the mixture of (S)-1 and (R)-1 was treated with p-anisidine (1.2 equiv), tetrabutylammonium iodide (TBAI, 1.0 equiv) and diisopropylethylamine (DIEA, 1.0 equiv) in CH2Cl2 at room temperature for 12 h, amino ester 8a was produced in 63% yield with 84:16 dr as shown in Table 1, entry 1. Also, six different N-protection groups of L-threonine were examined for the substitution with p-anisidine as shown in entries 2-7. The reactions of 2, 3, 4, and 7 bearing N-pivaloyl, N-Boc, Nbenzoyl, and N,N-dibenzyl groups gave slightly better drs ranging from 88:12 to 86:14, while the reactions of 5 and 6 bearing N-p-methoxybenzoyl and N-2-pyridinylcarbonyl groups gave lower drs compared to the reaction of 1. The dr and yield of the substitutions in Table 1 imply that -bromo carbon center is configurationally labile with respect to the rate of substitution and L-threonine-derived -bromo esters

N-Benzoyl-L-threonine-isopropyl-ester-mediated crystallization-induced dynamic resolution (CIDR) of configurationally labile α-bromo arylacetates has been investigated. The CIDR was successfully used for the asymmetric preparation of these compounds with up to 98:2 dr, under solution and solvent-free conditions. Subsequent nucleophilic substitution reactions with sulfur and oxygen nulceophiles gave α-thio and α-oxy arylacetates with up to 98:2 dr. The method was further developed for the preparation of highly enantioenriched 2-phenylthio-2-arylethanols with up to 97:3 er, and 1,4-benzoxazin-3-ones with up to 94:6 er.

We develop a radio receiver system operating at � � 1.3 mm for the 6 m telescope of Seoul Radio Astronomy Observatory. It consists of a dual polarization receiver, a couple of IF processing units, two FFT spectrometers, and associated software. By adopting sideband-separating superconductor mixers with image band terminated to waveguide load at 4.2 K, we achieve TRX � 100 K and Tsys less than 150 K at best weather condition over 210-250 GHz frequency range. The intermediate frequency signal of 3.5-4.5 GHz is down converted to 0-1 GHz and fed into the FFT spectrometers. The spectrometer covers 1 GHz bandwidth with a spectral resolution of 61 KHz. Test observations are conducted toward several radio sources to evaluate the performance of the system. Aperture and beam efficiencies measured by observing planets are found to be typically 44 � 59% and 47 � 61%, respectively over the RF band, which are consistent with those measured at 3 mm band previously.

The antimicrobial effect of a novel flavonoid (7-O-butylnaringenin) on Helicobacter pylori 26695, 51, and SS1 strains and its inhibitory effect on the urease activity of the strains were evaluated and compared with those of several natural flavonoids. First, various flavonoids were screened for antimicrobial activities using the paper disc diffusion method. Hesperetin and naringenin showed the strongest antimicrobial effects among the natural flavonoids tested, and thus hesperetin and naringenin were selected for comparison with 7-O-butylnaringenin. The antimicrobial effect of 7-O-butylnaringenin was greater than that of the hesperetin and naringenin. H. pylori 51 was more sensitive to 7-O-butylnaringenin (2 log reduction of colony forming units, p < 0.05) than the other two strains at 200 μM. 7-O-Butylnaringenin also showed the highest inhibitory effect against urease activity of H. pylori. Morphological changes of H. pylori 26695 treated with these flavonoids indicated that both hesperetin and 7-O-butylnaringenin at 200 μM damaged the cell membranes.

The objective of this study was to evaluate the antibacterial activity of a novel flavonoid, 7-O-butyl naringenin, as well as natural flavonoids (quercetin, naringenin) against methicillin-resistant Staphylococcus aureus (MRSA). 7-O-butyl naringenin showed great anti-MRSA, with a MIC (minimum inhibitory concentration) value of 0.625 mM. The number of cells treated with 25 μM 7-O-butyl naringenin was reduced by 5.2 log CFU/mL compared with the control (DMSO). The result indicated that 7-O-butyl naringenin was more effective than the two natural flavonoids against MRSA, and may have potential as a novel therapeutic agent for MRSA infections.

For asymmetric synthesis of α-substituted carboxylic acid derivatives, a variety of chiral auxiliaries have been used for the dynamic resolution of α-halo esters in nucleophilic substitution. 1 For example, L-lactamide-mediated dynamic kinetic resolution of α-bromo esters was successfully used for the asymmetric preparation of α-aryloxy carboxylic acids and oxazin-2-ones. 2 However, the application of Llactate as a chiral auxiliary was not effective for the dynamic resolution of α-halo esters. 3 In our continuous efforts to develop L-lactic acid as a chiral auxiliary for the dynamic resolution, we have recently found successful results with ethyl L-lactate. We herein report ethyl L-lactate-mediated dynamic kinetic resolution of α-bromo esters for the asymmetric preparation of α-amino acid derivatives. Treatment of racemic α-bromo-α-phenylacetic acid with ethyl L-lactate in the presence of DCC and DMAP provided α-bromo-α-phenyl ester (αRS)-1 with 50:50 diastereomeric ratio (dr) in 78% yield. When the diastereomeric mixture (αRS)-1 was treated with p-anisidine (p-MeOPhNH2, 1.5 equiv), tetrabutylammonium iodide (TBAI, 1.0 equiv) and diisopropylethylamine (DIEA, 1.0 equiv) in CH2Cl2 at room temperature for 24 h, the amino acid derivative 2 was produced in 86% yield with 97:3 dr as shown in Scheme 1. Following removal of L-lactate chiral auxiliary with Et3N in MeOH gave methyl phenylglycinate (R)-3 with 97:3 enantiomeric ratio (er) in 65% yield. 4 These results imply that α-bromo stereogenic center is configurationally labile with respect to the rate of substitution and (αRS)-1 is dynamically resolved in the substitution with the amine nucleophile. In a solvent screen, the reactions in CHCl3, ether, n-hexane and THF provided (αR)-2 with the same dr as in CH2Cl2, while the lower selectivities of 92:8 dr and 93:7 dr were observed in the reactions in DMF and CH3CN, respectively. In order to understand the asymmetric reaction pathway, we carried out two reactions with α-bromo-α-phenyl ester 1 of 67:33 dr. When 1 of 67:33 dr was allowed to reach thermodynamic equilibrium in the presence of DIEA, the diastereomeric ratio of recovered 1 was determined to be 49:51 dr. The result indicates that the thermodynamic stabilities of two diastereomers are almost the same, ruling out dynamic thermodynamic resolution as a primary pathway. In the reaction of 1 (67:33 dr) with p-anisidine under the same condition, 2 was obtained with the same stereoselectivity (97:3 dr) as in the reaction of 1 with 50:50 dr. In other words, the dr of product 2 is not dependent on the initial dr of 1. These preliminary results indicate that the epimerization is sufficiently fast with respect to the rate of substitution and the primary pathway of the asymmetric induction is a dynamic kinetic resolution. 1

Highly enantioenriched trans-2,3-disubstituted indolines have been prepared by Mitsunobu cyclodehydration of the amino alcohols obtained from (−)- or (+)-sparteine-mediated lithiation–substitution of ortho-alkyl substituted N-pivaloylanilines. Optimized cyclodehydration conditions are described, from which the combination of DEAD and PBu3 in CH3CN provides the best results.

Enantiopure N , N -dialkyl-( S )-2-amino-1,1,2-triphenyl­ethanols were prepared using a new synthetic methodology and tested for their ability to catalyze the enantioselective addition of diethylzinc to aldehydes. The structural modification of N-substituents of the catalysts led us to identify N -methyl- N -( S )-1-phenyl­ethyl-substituted 4d as an effective catalyst for the addition. Also disclosed is a kinetic resolution of racemic flavene-3-carbaldehydes with the chiral catalyst.

Piscidin 1 (Pis-1) from hybrid striped bass possesses antibacterial activities with high cytotoxicity. Previously, we reported that Pis-1[NkG], where Gly8 was substituted with positively charged Lys peptoid in Pis-1, shows high antibacterial activity with more potent bacterial cell selectivity than parent Pis-1 and Pis-1[PG] with Pro substitution at Gly8. Here, we investigated the effects of hydrophobic peptoid substitutions on antimicrobial activity and cytotoxicity of Pis-1. We designed Pis-1[NaG] and Pis-1[NlG] peptides, where Gly8 was replaced with alanine or leucine peptoids. Although hydrophobicity was increased in Pis-1[NaG] and Pis-1[NlG] compared with that in Pis-1[NkG], Pis-1, and Pis-1[PG], these peptides retained high antibacterial activity and showed no hemolytic activity when used at 100 μM. All peptoid-substituted peptides penetrated well the bacterial membrane and localized inside of the cytoplasm, while Pis-1 and Pis-1[PG] depolarized membrane severely. The flexible hinge structure formed by peptoid residues compared with the rigid bent structure formed by proline may explain their differential mechanisms of action. Most hydrophobic peptide, Pis-1[NlG], showed the most efficient inhibition of LPS (lipopolysaccharide)-induced nitric oxide production, indicating that it can be a potent antimicrobial peptide with anti-inflammatory activities. Peptoid substitution may facilitate the development of potent peptide drugs with bacterial cell selectivity.