bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Nonchiral Bislactim Diethoxy Ether as a Highly Stereo‐Inducing Synthon for Sterically Hindered, γ‐Branched α‐Amino Acids: A Practical, Large‐Scale Route to an Intermediate of the Novel Renin Inhibitor Aliskiren
Authors: Göschke Richard , Stutz Stefan , Heinzelmann Walter , Maibaum Jürgen 
Published: September 2003

AbstractThe diastereoselective synthesis of the sterically hindered, γ‐branched α‐amino acid derivative (2S,4S)‐24a and its N‐[(tert‐butoxy)carbonyl](Boc)‐protected alcohol (2S,4S)‐19, both key intermediates of a novel class of nonpeptide renin inhibitors such as aliskiren (1), is described. Initially, the analogous methyl ester (2S,4S)‐17 was obtained by alkylation of the chiral Schöllkopf dihydropyrazine (R)‐12a with the dialkoxy‐substituted alkyl bromide (R)‐11a, which proceeded with explicitly high diastereofacial selectivity (ds ≥98%) to give (2S,5R,2′S)‐13a (Scheme 4), followed by mild acid hydrolysis and N‐Boc protection (Scheme 5). Conversely, the complete lack of stereocontrol and poor yields for the reaction of (R)‐11a with the enantiomeric (S)‐12b suggested, in addition to the anticipated shielding effect by the iPr group at C(2) of the auxiliary, steric repulsion between the MeOC(6) and the bulky residues of (R)‐11a in the proposed transition state, which would strongly disfavor both the Si and Re attack of the electrophile (see Fig.). Based on this rationale, alkylation of the readily accessible achiral diethoxy‐dihydropyrazine 21 with (R)‐11a was found to provide a 95 : 5 mixture of diastereoisomers (2S,2′S)‐22a and (2R,2′S)‐23a in high yield (Scheme 6), which afforded in two steps and after recrystallization enantiomerically pure (2S,4S)‐24a. Similarly, the stereochemical course for the alkylation reactions of the related alkyl bromides (S)‐28a and (R)‐28b with both (R)‐12a and (S)‐12b as well as with the achiral 21 was investigated (Schemes 7–9). The precursor bromides (R)‐11a, (S)‐11b, (R)‐28a, and (S)‐28b were efficiently synthesized via the diastereoselective alkylation of the Evans 3‐isovaleroyloxazolidin‐2‐ones (R)‐7a and (S)‐7b either with bromide 6 or with benzyl chloromethyl ether, and subsequent standard transformations (Schemes 3 and 7). A practical and economical protocol of the preparation of (2S,4S)‐24a on a multi‐100‐g scale is given. This is the first report of the application of an achiral dihydropyrazine, i.e., in form of 21, as a highly stereo‐inducing synthon providing rapid access to a N‐protected γ‐branched α‐amino acid with (2S) absolute configuration.
Controlled Release of Perfumery Alcohols by Neighboring‐Group Participation. Comparison of the Rate Constants for the Alkaline Hydrolysis of 2‐Acyl‐, 2‐(Hydroxymethyl)‐, and 2‐Carbamoylbenzoates
Authors: de Saint Laumer Jean‐Yves , Frérot Eric , Herrmann Andreas 
Published: September 2003

AbstractA series of 2‐acylbenzoates 1 and 2, 2‐(hydroxymethyl)benzoates 3, 2‐carbamoylbenzoates 4–6, as well as the carbamoyl esters 7 or 8 of maleate or succinate, respectively (see Fig. 2), were prepared in a few reaction steps, and the potential use of these compounds as chemical delivery systems for the controlled release of primary, secondary, and tertiary fragrance alcohols was investigated. The rate constants for the neighboring‐group‐assisted alkaline ester hydrolysis were determined by anal. HPLC in buffered H2O/MeCN solution at different pH (Table 1). The rates of hydrolysis were found to depend on the structure of the alcohol, together with the precursor skeleton and the structure of the neighboring nucleophile that attacks the ester function. Primary alcohols were released more rapidly than secondary and tertiary alcohols, and benzoates of allylic primary alcohols (e.g., geraniol) were hydrolyzed 2–4 times faster than their homologous saturated alcohols (e.g., citronellol). For the same leaving alcohol, 2‐[(ethylamino)carbonyl]benzoates cyclized faster than the corresponding 2‐(hydroxymethyl)benzoates, and much faster than their 2‐formyl and 2‐acetyl analogues (see, e.g., Fig. 4). Within the carbamoyl ester series, 2‐[(ethylamino)carbonyl]benzoates were found to have the highest rate constants for the alkaline ester hydrolysis, followed by unsubstituted 2‐(aminocarbonyl)benzoates, or the corresponding isopropyl derivatives. To rationalize the influence of the different structural changes on the hydrolysis kinetics, the experimental data obtained for the 2‐[(alkylamino)carbonyl]benzoates were compared with the results of density‐functional computer simulations (Table 2 and Scheme 4). Based on a preliminary semi‐empirical conformation analysis, density‐functional calculations at the B3LYP/6‐31G** level were carried out for the starting precursor molecules, several reaction intermediates, and the cyclized phthalimides. For the same precursor skeleton, these simple calculations were found to model the experimental data correctly. With an understanding of the influence of structural parameters on the rate constants obtained in this work, it is now possible to influence the rates of hydrolysis over several orders of magnitude, to design tailor‐made precursors for a large variety of fragrance alcohols, and to predict their efficiency as controlled‐release systems in practical applications.
Synthesis of Psoralen Analogues Based on Dibenzofuran
Authors: Oliveira Ana M. A. G. , Raposo M. Manuela M. , Oliveira‐Campos Ana M. F. , Griffiths John , Machado Antonio E. H. 
Published: September 2003

AbstractThe syntheses of four novel psoralen derivatives, 6a–d, of the benzofurocoumarin (=benzofuro[1]benzopyranone) type containing an ester group are described. These compounds might be of interest in PUVA (psoralen long‐wave ultraviolet radiation) therapy. The overall efficiency of the synthetic procedure is greatly limited by the low yields for the penultimate step, i.e., formylation of the dibenzofuranols 3a,c or protected dibenzofuranol 4d to the carboxaldehydes 5 (Scheme 4). However, the final stage to form the pyranone ring from 5a–d proceeds smoothly (Scheme 5).
Crystal Structure and Chemical Stabilization of the Triple Salt (KHSO5)2⋅KHSO4⋅K2SO4
Authors: Ermer Otto , Röbke Christof 
Published: September 2003

AbstractThe title compound, a versatile and chemically stabilized oxidant, which is used technologically on a large scale, builds up an intercalation‐type of crystal structure with alternating sheets of sulfate and peroxomonosulfate anions, interspersed by the potassium cations. The sulfate ions are joined by a very short but nonetheless probably asymmetric hydrogen bond. At room temperature, the HSO$\rm{_{5}^{-}}$ ions show dynamic orientational/conformational disorder in the area of the hydrogenperoxo group, which disappears at 100 K. The chemical stabilization of the triple salt is ascribed to shielding of the HSO$\rm{_{5}^{-}}$ ions effected by the intercalation between the sulfate sheets and, furthermore, by the large and abundant K+ ions of this potassium‐rich compound.
Indoloquinazoline Alkaloids from Araliopsis tabouensis
Authors: Christopher Ezugwu , Bedir Erdal , Dunbar Chuck , Khan Ikhlas A. , Okunji Christopher O. , Schuster Brian M. , Iwu Maurice M. 
Published: September 2003

AbstractThree new indoloquinazolidine‐type alkaloids, 8,13‐dihydro‐2‐methoxyindolo[2′,3′: 3,4]pyrido[2,1‐b]quinazolin‐5(7H)‐one (1), 8,13‐dihydro‐2‐methoxy‐13‐methylindolo[2′,3′: 3,4]pyrido[2,1‐b]quinazolin‐5(7H)‐one (2), and 5,8,13,14‐tetrahydro‐2‐methoxy‐14‐methyl‐5‐oxo‐7H‐indolo[2′,3′: 3,4]pyrido[2,1‐b]quinazolim‐6‐iun chloride (3) were isolated from Araliopsis tabouensis, together with three known compounds. The structures of the new compounds were determined primarily from 1D‐ and 2D‐NMR analysis. The antimalarial activities of compounds 1–5 were evaluated against Plasmodium falciparum D6 and W2 clones. The IC50 values in antimalarial bioassay for compounds 2–5 varied from 1.8 to 4.7 μg/ml.
A Sensitive and Selective High‐Throughput Screening Fluorescence Assay for Lipases and Esterases
Authors: Nyfeler Erich , Grognux Johann , Wahler Denis , Reymond Jean‐Louis 
Published: September 2003

AbstractLong‐chain fatty acid esters of 7‐(3,4‐dihydroxybutyloxy)‐2H‐1‐benzopyran‐2‐one (6) such as octanoate 2a are shown to be exceptionally sensitive and selective fluorogenic substrates for lipases and esterases. Umbelliferone (8) is released upon hydrolysis of the ester function in 2a in the presence of bovine serum albumin and sodium periodate. These substrates are at least by one order of magnitude more sensitive to lipases than the commercial fluorogenic substrate 4‐methylumbelliferyl heptanoate. Furthermore, they are stable to a broad range of pH‐induced‐ and thermal‐hydrolysis conditions and do not react with non‐catalytic proteins such as bovine serum albumin (BSA).
β‐Amino Alcohol Properfumes
Authors: Yang Yongzheng , Wahler Denis , Reymond Jean‐Louis 
Published: September 2003

AbstractAmino‐alcohol derivatives of fragrant, volatile aldehydes and ketones were synthesized in a one‐pot procedure by sequential cyanohydrin formation with trimethylsilyl cyanide and reduction with lithium aluminium hydride, or by ammonolysis of epoxide precursors. The amino alcohols are nonvolatile, stable properfumes releasing fragrant carbonyls by oxidation with sodium periodate or sodium bismuthate. Examples include amino alcohol properfumes of citronellal,Lilial®, lauryl aldehyde, menthone, benzaldehyde, and anisaldehyde.
The influence of framing on attitudes toward diversity training
Authors: Holladay Courtney L. , Knight Jennifer L. , Paige Danielle L. , Quiñones Miguel A. 
Published: September 2003

AbstractAlthough diversity training is becoming an integral component of organizations, little empirical research on
the topic exists. The study examined here investigated how framing of diversity training (title, focus of
content, assignment) and gender influenced participants' attitudes. In this study, 160 adults (72
men, 88 women; 124 white; 36 minority) read a diversity course description and answered questions assessing
their attitudes about the course and the organization. Results revealed that (1) a frame with a
traditional title and a broad focus was responded to most favorably by participants, (2) men reacted
more negatively than women to the diversity training course, and (3) men reacted more negatively than
women to a frame with a narrow focus and remedial assignment. Findings are discussed in terms of the effect that
different frames can have on participants' pretraining attitudes toward diversity training. Implications for
researchers and consultants are also discussed.
Determining the relationship between drivers' level of education, training, working conditions, and job performance in Kenya
Authors: Nafukho Fredrick Muyia , Hinton Barbara E. 
Published: September 2003

AbstractOne major issue in human resource development (HRD) is to determine factors that predict the
performance of employees. The primary purpose of this study was to determine how level of education, training, and
the working conditions of matatu (public service vehicle) drivers determined their job
performance in terms of reduced road traffic accidents. Proportionate and simple random sampling techniques were
employed to select 143 drivers who completed and returned the questionnaires. Multiple regression analysis was
used to test the hypotheses stated. The findings indicate that the variables of driver experience and hours worked
had a significant relationship with the dependent variable rates of traffic accidents per driver as hypothesized.
The variables of education level, training, salary earned, and average speed traveled did not have a significant
relationship with the dependent variable.
Using personality tests in leadership development: Test format effects and the mitigating impact of explanations and feedback
Authors: Harland Lynn K. 
Published: September 2003

AbstractOrganizations using personality tests in management development programs must choose from an array of
personality tests and formats. The most common formats are normative (for example, Likert type) and
forced choice. Although there are some potential advantages to using the forced‐choice format for
development, it is possible that participants may view the forced‐choice format more negatively than the
normative format. Hypothesis 1 proposed that participants would initially view the forced‐choice format as
less accurate, less respectful, less useful, and providing less test taker control. Hypothesis 2 proposed that an
explanation of forced‐choice format benefits would mitigate initial negative reactions. Finally, hypothesis
3 proposed that receiving test feedback would mitigate negative perceptions of forced‐choice format
accuracy and usefulness. The participants, 255 part‐time M.B.A. students in a leadership development
course, were randomly assigned to three experimental conditions: normative, forced choice with an explanation, and
forced choice with no explanation.
The effect of workplace gender and race demographic composition on hiring through employee referrals
Authors: Taber Mary E. , Hendricks Wallace 
Published: September 2003

AbstractThis quantitative study tests whether the gender and race composition of the workplace helps explain why there
are systematic differences in how employees are hired across gender and race. We find evidence that differences
across racial groups in the use of employee referrals may be explained partly by differences in the race
composition of the workplace. We also find evidence that recruiting source models that do not include workplace
demographic composition may misestimate the effect of the new employee's race on the hiring source.
Gender‐based approach to the understanding of leadership roles among retail managers
Authors: Kim Hye‐Shin , Shim Soyeon 
Published: September 2003

AbstractUsing survey data (n = 205) obtained from retail managers and executives of national retail
chain store companies, we sought to identify the effect of gender on leadership roles in conjunction with
personal
values, job characteristics, and other personal values. Quinn's theoretical model of competing leadership
roles
(1984, 1988) was used as a conceptual framework. Results indicated that the members of the female
group
perceived themselves to display a higher level of mentor and broker roles than did the members of the male
group.
Further analysis indicated that certain personal values such as social affiliation and growth and development
predicted the mentor and broker roles, respectively, without diminishing the effect of gender. Finally,
perceived
job characteristics (that is, feedback) also predicted the broker role. Theoretical and managerial
implications are discussed.
Shaping the future: Writing up the method on qualitative studies
Authors: Rocco Tonette S. 
Published: September 2003

AbstractAs the qualitative method editor for HRDQ, I report my observations on qualitative
manuscripts to the editorial board at the annual Academy of Human Resource Development meeting. The problem
areas identified in the manuscripts reviewed are organization and format, the relationship of the conceptual
and method, the method (type of study, conceptual framework, sample, data collection, data analysis,
integrity measures, and data management), and discussion and data presentation. Here, I share the portion
of the report on method and data presentation with novice researchers in an effort to improve submissions.
Morphometric relationships of take‐off speed in anuran amphibians
Authors: Choi Inho , Shim Jae Han , Ricklefs Robert E. 
Published: September 2003

AbstractLocomotory speed correlates with muscle mass (determining force and stride rate), limb length (stride rate and distance), and laterally compressed body trunk (force and stride distance). To delineate generalization of the locomotory‐morphometric relationships specifically in anuran amphibians, we investigated take‐off speed and the three morphological variables from seven species, Rana nigromaculata, R. rugosa, and Bombina orientalis, Eleuthrodectilus fitzingeri, E. diastema, Bufo typhonius, Colostethus flotator and Physalaemus pustulosus. The fastest jumper E. fitzingeri (3.41 m s−1) showed 2.49‐fold greater speed than the slowest B. typhonius. Take‐off speed correlated well with both thigh muscle mass relative to body mass and hindlimb length relative to snout‐vent length (HL/SVL), but poorly correlated with the inter‐ilial width relative to SVL. The best morphological predictor was HL/SVL (speed=−3.28+3.916 HL/SVL, r=0.968, P<0.0001), suggesting that anuran take‐off speed is portrayed well with high gear and acceleration distance characterized by hindlimbs. J. Exp. Zool. 299A:99–102, 2003. © 2003 Wiley‐Liss, Inc.
Fecal Corticosterone Assessment in the Epaulette Shark, Hemiscyllium ocellatum
Authors: Karsten Amanda H. , Turner John W. 
Published: September 2003

AbstractThe present study examined the feasibility of measuring the steroid hormone corticosterone in fecal extracts of epaulette sharks, Hemiscyllium ocellatum. Six immature, captive‐raised epaulette sharks (four females and two males) were obtained from two different zoos and were maintained in a closed‐system, 530–liter aquarium. After a one‐month adaptation, fecal samples were collected daily from each animal for 33 days. Five‐day sets of samples were pooled within animals to insure sufficient material for analysis. Fecal hormone extraction was achieved using repeated cycles of dichloromethane and aqueous washes. The levels of corticosterone were measured by reverse‐phase high‐performance liquid chromatography (HPLC). Corticosterone presence in HPLC eluent peaks from fecal extracts was determined by comparison of the elution pattern of corticosterone standard with the elution patterns of fecal extracts with and without the addition of tritiated corticosterone or exogenous, unlabeled corticosterone. Exclusive presence of corticosterone in HPLC eluent peaks presumed to be corticosterone was determined by nuclear magnetic resonance mass spectrometry. Corticosterone levels, calculated from a 10–point standard curve, ranged from 1.2 to 20.9 ng/g feces across all sharks, with 92.3% of values being ≤13.5 ng/g. Within individuals, the lowest average for corticosterone levels across 33 days was 2.6±0.4 ng/g feces, and the highest average was 8.4±2.2 ng/g feces. This study demonstrated that corticosterone was extractable from and reliably measurable in fecal extracts of epaulette sharks. This is the first evidence of this hormone in epaulette sharks and the first report of fecal corticosterone in elasmobranchs. J. Exp. Zool. 299A:188–196, 2003. © 2003 Wiley‐Liss, Inc.
Finiteness of U‐rank implies simplicity in homogeneous structures
Authors: Hyttinen Tapani 
Published: September 2003

AbstractA (large) superstable homogeneous structure is said to be simple if every complete type over any set A has a free extension over any B ⊇ A. In this paper we give a characterization for this property in terms of U‐rank. As a corollary we get that if the structure has finite U‐rank, then it is simple. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the complexity of categoricity in computable structures
Authors: White Walker M. 
Published: September 2003

AbstractWe investigate the computational complexity the class of Γ‐categorical computable structures. We show that hyperarithmetic categoricity is Π11‐complete, while computable categoricity is Π04‐hard. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polycarbonate Crystallization by Vapor‐Grown Carbon Fiber with and without Magnetic Field
Authors: Takahashi Tatsuhiro , Yonetake Koichiro , Koyama Kiyohito , Kikuchi Tokio 
Published: September 2003

AbstractPolycarbonate (PC)/vapor‐grown carbon fiber (VGCF™) composite was prepared through melt compounding. It was unexpectedly found from differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) that the crystallization of PC was substantially accelerated in the presence of the ordered graphite surface of VGCF™. To make an aligned structure of PC crystallization together with the orientation of VGCF™, a magnetic field of 2.4 T was applied to the composite under several temperature profiles. The WAXD pattern revealed that not only dispersed VGCF™ but also matrix PC crystallization was magnetically aligned through the optimization of processes. The evidence for PC crystallization by VGCF™ with and without magnetic force is described.Optical micrograph (a) and WAXD pattern (b) of PC/VGCF™ (95:5 wt. ratio) composite which was treated under a magnetic field (vertical direction) of 2.4 T under an optimized heating profile.magnified imageOptical micrograph (a) and WAXD pattern (b) of PC/VGCF™ (95:5 wt. ratio) composite which was treated under a magnetic field (vertical direction) of 2.4 T under an optimized heating profile.
Polymerization of Norbornene with CoCl2 and Pyridine Bisimine Cobalt(II) Complexes Activated with MAO
Authors: Pelascini Frédéric , Peruch Frédéric , Lutz Pierre J. , Wesolek Marcel , Kress Jacky 
Published: September 2003

AbstractAddition polymerization of norbornene was performed with several pyridine bis(imine) cobalt dichloride complexes activated with methylaluminoxane (MAO), first described for ethylene polymerization. For the first time, norbornene was also polymerized with CoCl2 associated to MAO. The influence of several reaction parameters has been investigated. Quite different behavior was observed compared with ethylene polymerization. Moreover, the copolymerization of ethylene and norbornene with these complexes was not possible but led to a mixture of both homopolymers.The pyridine bis(imine) cobalt dichloride complexes used in this study.magnified imageThe pyridine bis(imine) cobalt dichloride complexes used in this study.
Transparent Nonlinear Optical Polymers for All‐Optical Wavelength Converters in Optical Fiber Communications
Authors: Park Seung Koo , Do Jung Yun , Ju Jung‐Jin , Park Suntak , Kim Min‐su , Lee Myung‐Hyun 
Published: September 2003

AbstractAfter synthesizing two chromophores with imine, we prepared acrylic nonlinear optical (NLO) polymers that contained the chromophores for all‐optical wavelength converters in optical fiber communication. The polymers show high d33, 35 pm · V−1, at 1.55 μm (pumping beam), considering their low losses, −3.0 dB · cm−1, at a wavelength of 0.785 μm (near second harmonic signal beam of the pumping beam). This result means that the polymers are good candidates for wavelength converters of an approximately 1.55 μm signal beam.UV‐vis spectra of NLO chromophores and polymers.magnified imageUV‐vis spectra of NLO chromophores and polymers.
Determination of Propagation Rate Coefficient of Acrylates by Pulsed‐Laser Polymerization in the Presence of Intramolecular Chain Transfer to Polymer
Authors: Nikitin Anatoly N. , Castignolles Patrice , Charleux Bernadette , Vairon Jean‐Pierre 
Published: September 2003

AbstractUnusual difficulties are faced in the determination of propagation rate coefficients (kp) of alkyl acrylates by pulsed‐laser polymerization (PLP). When the backbiting is the predominant chain transfer event, the apparent kp of acrylates determined in PLP experiments for different frequencies should range between kp (propagation rate coefficient of the secondary radicals) at high frequency and k at low frequency. The k value could be expressed from kinetic parameters: $k_{\rm p}^{{\rm av}} = k_{\rm p} - {{k_{\rm p} - k_{{\rm p}2} } \over {1 + {{k_{{\rm p}2} [{\rm M}]} \over {k_{{\rm fp}} }}}}$, where kfp is the backbiting rate coefficient, kp2 is the propagation rate coefficient of mid‐chain radicals, and [M] is the monomer concentration.Apparent propagation rate coefficients determined for different frequencies by simulating the PLP of n‐butyl acrylate at 20 °C. Horizontal full lines show the values of kp and k.magnified imageApparent propagation rate coefficients determined for different frequencies by simulating the PLP of n‐butyl acrylate at 20 °C. Horizontal full lines show the values of kp and k.