bluuebunny/crossref_metadata_2025 huggingface dataset:
The Spatial Representation of Market Information
Authors: DeSarbo Wayne S. , Degeratu Alexandru M. , Wedel Michel , Saxton M. Kim
Published: December 2003

To be used effectively, market knowledge and information must be structured and represented in ways that are parsimonious and conducive to efficient managerial decision making. This manuscript proposes a new latent structure spatial model for the representation of market information that meets this requirement. When applied to a priori defined (e.g., socioeconomic) segments, our proposed methodology provides a new way to display marketing data parsimoniously via dimension reduction through a factor-analytic specification. In post hoc studies, we simultaneously derive market segments from the data and represent the structure of market information within each of the unobserved, derived groups/segments. We summarize all relevant information concerning derived market segments via a series of maps that prove conducive to the quick and accurate dissemination of customer and competitor market information. The associations between the variables are captured in a reduced space, where each variable is represented by a vector that emanates from the origin and terminates on a hypersphere of unit (the vector length is arbitrary) radius (e.g., a unit circle in a two-dimensional space). The angles between the variable vectors capture the correlation structure in the reduced space. The method is very general and can be utilized to identify latent structures in a wide range of marketing applications. We present an actual commercial marketing application involving the (normalized) prescription shares (of specialists) of ethical drugs to demonstrate the effectiveness of representing market information in this manner and to reveal the advantage of the proposed methodology over a more general finite mixture-based method. The proposed methodology derives three segments that tend to group specialists with respect to the stage of adoption of innovation in this therapeutic category. The specialists in the first group appear to be laggards because they prescribe more of the older class of brands. However, they also have a higher-than-average preference for a newer and somewhat cheaper brand. This suggests that some of the specialists belonging to this segment may be price sensitive, while others may exhibit a slower adoption cycle, replacing the older class with the newer brands, and thus, skip one stage in the cycle of innovation. The specialists in the second segment are heavy users of the newer class of brands but are not particularly fast to adopt the latest brands. Finally, the last segment clearly consists of innovators. Traditionally, pharmaceutical marketers have viewed specialists in one of two extremes—all specialists are the same (i.e., the market has only one segment) or all specialists are very different (i.e., the market consists of 10,000+ segments of one physician each). Not surprisingly, this analysis suggests a more moderate perspective: specialists adopt new products at different rates.
Creating Win–Win Trade Promotions: Theory and Empirical Analysis of Scan-Back Trade Deals
Authors: Drèze Xavier , Bell David R.
Published: December 2003

Manufacturer trade promotion spending is second only to cost of goods sold as a profit-and-loss item, yet manufacturers often lose money on these deals as a result of forward-buying by retailers. The search for more effective forms of trade promotion and the availability of scanners at cash registers has led to the emergence of a new type of trade deal—the scan-back—that gives retailers a discount on unitssoldduring the promotion rather than on unitsbought.

We develop a theory to compare retailer pricing decisions and profitability under scan-back and traditional off-invoice trade deals. We show that, when the terms of the trade deal are identical, retailers prefer off-invoice trade deals and manufacturers prefer scan-backs. Manufacturers can, however, redesign the scan-back to leave the retailer weakly better off and leave themselves strictly better off. Using proprietary data from the beverage category, we conduct an empirical analysis and find that during the promotion period scan-back trade deals, relative to off-invoice deals: (1) Do not cause excess ordering and (2) generate higher retail sales through lower retail prices. Implications for researchers and managers are discussed.
Massively Categorical Variables: Revealing the Information in Zip Codes
Authors: Steenburgh Thomas J. , Ainslie Andrew , Engebretson Peder Hans
Published: December 2003

We introduce the idea of a massively categorical variable, a variable such as zip code that takes on too many values to treat in the standard manner. We show how to use a massively categorical variable directly as an explanatory variable.

As an application of this concept, we explore several of the issues that analysts confront when trying to develop a direct marketing campaign. We begin by pointing out that the data contained in many of the common sources are masked through aggregation in order to protect consumer privacy. This creates some difficulty when trying to construct models of individual level behavior.

We show how to take full advantage of such data through a hierarchical Bayesian variance components (HBVC) model. The flexibility of our approach allows us to combine several sources of information, some of which may not be aggregated, in a coherent manner. We show that the conventional modeling practice understates the uncertainty with regard to its parameter values.

We explore an array of financial considerations, including ones in which the marginal benefit is non-linear, to make robust model comparisons. To implement the decision rules that determine the optimal number of prospects to contact, we develop an algorithm based on the Monte Carlo Markov chain output from parameter estimation. We conclude the analysis by demonstrating how to determine an organization's willingness to pay for additional data.
Price Uncertainty and Consumer Search: A Structural Model of Consideration Set Formation
Authors: Mehta Nitin , Rajiv Surendra , Srinivasan Kannan
Published: December 2003

We offer an econometric framework that models consumer's consideration set formation as an outcome of her costly information search behavior. Because frequently purchased products are characterized by frequent price promotions of varying depths of discounts, a consumer faces significant uncertainty about the prices of the brands. The consumers engage in a fixed-sample search strategy that results in their discovering the posted prices of a subset of the available brands. This subset is referred to as the consumer's “consideration set.”

The proposed model is estimated using the scanner data set for liquid detergents. Our key empirical results are: (i) consumers zincur significant search costs to discover the posted prices of the brands; (ii) whereas in-store displays and feature ads do not influence consumers' quality perceptions of the brands, they significantly reduce search costs for observing the prices of the brands; (iii) per capita income of consumer's household significantly increases her search costs; and (iv) the consumers' price sensitivity is seriously underestimated if we were to assume that consumers get to know all the posted prices at zero cost. The proposed model is also estimated for the ketchup category to enable us to do cross-category comparisons of consumers' price search behavior
Editorial: Compartmentalized Reviews and Other Initiatives: Should Marketing Scientists Review Manuscripts in Consumer Behavior?
Authors: Shugan Steven M.
Published: December 2003

Effectively solving problems requires proper organization. Like other academic disciplines, our discipline must organize around our fundamental problems rather than around our procedures (i.e., tools, approaches, methods). Only that organization ensures healthy debate and constructive communication on relevant research questions.

Three initiatives might help foster a transition from a procedure-based to a problem-based organization. One initiative is compartmentalized reviews. Rather than only assigning reviews based on the technical procedures used in a manuscript (e.g., experiments), we assign at least one reviewer, whose expertise is in the problem domain (e.g., advertising), to review only that part of the manuscript (e.g., relevancy to advertisers). Another initiative is to avoid dichotomous certification (i.e., correct or incorrect) for procedures. All procedures yield evidence that forms a multidimensional continuum from circumstantial to overwhelming. Sometimes, precision in stating the conclusion is more important than precision in the procedure. Finally, research streams on marketing questions are essential—no one article is definitive. To foster these streams,Marketing Sciencemust encourage (to some degree) articles that expand on research previously published inMarketing Science. WhenMarketing Sciencepublishes an article, it has some obligation to give some priority to manuscripts that build on the same topic (i.e., not to label them as “incremental”).
In the Eye of the Beholder: An Analysis of the Relative Value of a Top Sales Rep Across Firms and Products
Authors: Godes David
Published: December 2003

We ask the question, “when should the most highly skilled salespeople sell the best products?” Our main result is that the highly skilled reps should sell better products when the task is very complex and worse products when the task is very simple. This is shown using a general analytical model of selling in which sales are a joint function of the salesperson's skill and the complexity of the selling task. Complexity varies across products and industries. Intuitively, when the selling task is complex, few salespeople ofanylevel of ability will be successful with a low-quality product. Therefore, the high-skill rep's value is higher on the better product. Conversely, when the task is simple, salespeople ofanyability can sell the better product fairly easily so the high-skill rep's impact is more pronounced on the worse product. This general result offers insight into many key problems: Which salespeople should we hire? How should we organize our salespeople? How should we allocate training funds? We show that the insights hold for salespeople that eithercreatevalue or simplypersuadethe customer about the product's value. Finally, we contrast this set of questions with the question ofhow manysalespeople the firm should hire. We find that the firm that has the biggest sales force does not always have the best.
The International Takeoff of New Products: The Role of Economics, Culture, and Country Innovativeness
Authors: Tellis Gerard J. , Stremersch Stefan , Yin Eden
Published: December 2003

Sales takeoff is vitally important for the management of new products. Limited prior research on this phenomenon covers only the United States. This study addresses the following questions about takeoff in Europe:

1) Does takeoff occur as distinctly in other countries, as it does in the United States?

2) Do different categories and countries have consistently different times-to-takeoff?

3) What economic and cultural factors explain the intercountry differences?

4) Should managers use a sprinkler or waterfall strategy for the introduction of new products across countries?

We gathered data on 137 new products across 10 categories and 16 European countries.

We adapted the threshold rule for identifying takeoff (Golder and Tellis 1997) to this multinational context. We specify a parametric hazard model to answer the questions above. The major results are as follows:

1) Sales of most new products display a distinct takeoff in various European countries, at an average of six years after introduction.

2) The time-to-takeoff varies substantially across countries and categories. It is four times shorter for entertainment products than for kitchen and laundry appliances. It is almost half as long in Scandinavian countries as in Mediterranean countries.

3) While culture partially explains intercountry differences in time-to-takeoff, economic factors are neither strong nor robust explanatory factors.

4) These results suggest distinct advantages to a waterfall strategy for introducing products in international markets.
Fast Polyhedral Adaptive Conjoint Estimation
Authors: Toubia Olivier , Simester Duncan I. , Hauser John R. , Dahan Ely
Published: December 2003

We propose and test new adaptive question design and estimation algorithms for partial profile conjoint analysis. Polyhedral question design focuses questions to reduce a feasible set of parameters as rapidly as possible. Analytic center estimation uses a centrality criterion based on consistency with respondents' answers. Both algorithms run with no noticeable delay between questions.

We evaluate the proposed methods relative to established benchmarks for question design (random selection, D-efficient designs, adaptive conjoint analysis) and estimation (hierarchical Bayes). Monte Carlo simulations vary respondent heterogeneity and response errors. For low numbers of questions, polyhedral question design does best (or is tied for best) for all tested domains. For high numbers of questions, efficient fixed designs do better in some domains. Analytic center estimation shows promise for high heterogeneity and for low response errors; hierarchical Bayes for low heterogeneity and high response errors. Other simulations evaluate hybrid methods, which include self-explicated data.

A field test (330 respondents) compared methods on both internal validity (holdout tasks) and external validity (actual choice of a laptop bag worth approximately $100). The field test is consistent with the simulation results and offers strong support for polyhedral question design. In addition, marketplace sales were consistent with conjoint-analysis predictions.
Bayesian Statistics and Marketing
Authors: Rossi Peter E. , Allenby Greg M.
Published: December 2003

Bayesian methods have become widespread in marketing literature. We review the essence of the Bayesian approach and explain why it is particularly useful for marketing problems. While the appeal of the Bayesian approach has long been noted by researchers, recent developments in computational methods and expanded availability of detailed marketplace data has fueled the growth in application of Bayesian methods in marketing. We emphasize the modularity and flexibility of modern Bayesian approaches. The usefulness of Bayesian methods in situations in which there is limited information about a large number of units or where the information comes from different sources is noted. We include an extensive discussion of open issues and directions for future research.
Understanding High-Stakes Consumer Decisions: Mammography Adherence Following False-Alarm Test Results
Authors: Kahn Barbara E. , Luce Mary Frances
Published: December 2003

Consumers often have to decide whether to acquire information in high-stakes decision domains. We study women in mammography waiting rooms to test how a “false-alarm” result (i.e., an indication that a malady is present when a “more accurate” follow-up test reveals it is not) affects willingness to get retested. In Study 1 we show that, given a false-alarm result, life-threatening test consequences are associated with more disutility for future testing than when test consequences are less significant; this does not hold for normal test results. In Study 2 in the mammography context, we show that patients receiving a false-alarm result experienced more stress, were less likely to believe that a positive mammography result indicated cancer, and more likely to delay mammography than patients receiving normal results unless they were also told that they may be vulnerable to breast cancer in the future. We show that delays in planned adherence following a false-alarm result can be mitigated by an information intervention. Finally, we have preliminary evidence that a previous history of false-positive results can cause a consumer to both react more negatively to emotional stress and respond more positively to coping information.
A Fuzzy Set Model of Search and Consideration with an Application to an Online Market
Authors: Wu Jianan , Rangaswamy Arvind
Published: December 2003

Several two–stage choice models (consideration stage plus choice stage) have been proposed in the marketing literature. We extend this literature by developing a more general model that incorporates how consumer search influences the degree to which they consider various brands. To test the validity and value of our model, we operationalized it with data obtained from Peapod, an online grocer, where we tracked consumers’ search processes. We demonstrate that our model performs better than competing models on all the key criteria. New choice models, such as the ones proposed here, are necessary for deriving managerially relevant understanding of choice behavior in online markets. Our empirical results suggest that consumers search both their internal memory and external information at the store to determine the degree to which they consider various brands. Consumers are also heterogeneous with respect to their capability to process external information. For some consumers, external information search dramatically increases the degree to which they consider various brands; but, for others, it has little impact on their consideration. We also find that certain features (e.g., personal lists) reduce consideration set sizes, whereas other features (e.g., sort) increase consideration set sizes.
Monotone Optimal Policies for a Transient Queueing Staffing Problem
Authors: Fu Michael C. , Marcus Steven I. , Wang I-Jeng
Published: December 2003

We consider the problem of determining the optimal policy for staffing a queueing system over multiple periods, using a model that takes into account transient queueing effects. Formulating the problem in a dynamic programming setting, we show that the optimal policy follows a monotone optimal control by establishing the submodularity of the objective function with respect to the staffing level and initial queue size in a period. In particular, this requires proving that the system occupancy in a G/M/s queue is submodular in the number of servers and initial system occupancy.
Additive Impact of Childhood Emotional, Physical, and Sexual Abuse on Suicide Attempts among Low‐Income African American Women
Authors: Anderson Page L. , Tiro Jasmin A. , Price Ann Webb , Bender Marnette A. , Kaslow Nadine J.
Published: December 2003

This study examines the association between exposures to multiple forms of childhood abuse (emotional, physical, sexual) and adult suicidal behavior in a sample of low‐income, African American women. We hypothesized a linear relation between childhood abuse and risk for making a suicide attempt, such that the more forms of childhood abuse to which a woman was exposed, the greater her risk would be to make a suicide attempt. Logistic regression analyses revealed that, compared to women who did not report any experiences of childhood abuse, women who experienced one, two, or three forms of abuse were 1.83, 2.29, or 7.75 times more likely to attempt suicide, respectively (all statistically significant). Furthermore, compared to women who reported one or two types of abuse, women who reported all three types of abuse were statistically more likely to attempt suicide. These findings have implications for clinicians working with African American women who report either childhood abuse or exhibit suicidal behavior.
Neighborhood Predictors of Hopelessness among Adolescent Suicide Attempters: Preliminary Investigation
Authors: Perez‐Smith Alina , Spirito Anthony , Boergers Julie
Published: December 2003

The role of neighborhood factors in predicting hopelessness among adolescent suicide attempters was examined in this study. Forty‐eight adolescents who attempted suicide were administered measures of hopelessness and depression. Family socioeconomic status (SES) was calculated based on family demographics and characteristics of neighborhood context were examined using a geocoding software package. Adolescents who lived in neighborhoods with weak social networks reported higher levels of hopelessness, even after controlling for SES and depression. These preliminary findings suggest that environmental context may play a role in the emotional status of adolescents who attempt suicide.
Situational Determinants of Inpatient Self‐Harm
Authors: Nijman Henk L.I. , Campo Joost M.L.G.À
Published: December 2003

Auto‐aggressive individuals have a higher likelihood of engaging in interpersonal violence, and vice versa. It is unclear, however, whether ward circumstances are involved in determining whether aggression‐prone patients will engage in auto‐aggressive or outwardly directed aggressive behavior. The current study focuses on the situational antecedents of self‐harming behavior and outwardly directed aggression of psychiatric inpatients. Inwardly and outwardly aggressive behavior were monitored on a locked 20‐bed psychiatric admissions ward for 3.5 years with the Staff Observation Aggression Scale‐Revised (SOAS‐R). A map of the ward was attached to each SOAS‐R form, enabling staff members to specify locations of aggressive incidents. Time of onset, location, and provoking factors of auto‐aggressive incidents were compared to those connected to aggression against others or objects. Of a total of 774 aggressive incidents, 154 (20%) concerned auto‐aggressive behavior. Auto‐aggression was significantly more prevalent during the evening (i.e., 50% compared to 32%), and reached its highest level between 8 and 9 P.M. (17% compared to 7%). The majority of self‐harming acts (66%) were performed on patients' bedrooms. Outwardly directed aggression was particularly common in the day‐rooms (24%), the staff office (19%), the hallways of the ward (14%), and the dining rooms (10%). Provoking factors of auto‐aggressive behavior are less often of an interactional nature compared to outwardly directed aggression. The results suggest that a lack of stimulation and interaction with others increases the risk of self‐injurious behavior. Practical and testable measures to prevent self‐harm are proposed.
Use of Statistical Techniques in Studies of Suicide Seasonality, 1970 to 1997
Authors: Hakko Helinä , Räsänen Pirkko , Tiihonen Jari , Nieminen Pentti
Published: December 2003

The effect of seasons on suicides has been suggested repeatedly. In order to reveal a true seasonal pattern, an appropriate statistical technique, which is sensitive to a specific type of cyclic variation in the data, must be chosen. This study is a review of the use of statistical techniques for seasonality and of some important characteristics of study samples that were evaluated from 46 original suicide seasonality articles published in major psychiatric journals. The results showed that statistical techniques were applied in a majority of articles, but they were commonly lacking regarding analyses, which compared seasonal patterns among subgroups of a population. In recent studies more sophisticated statistical techniques were utilized for seasonality, like spectral analyses, as compared with earlier studies, in which the emphasis was on chi‐square tests. Lack of reporting essential features of the data, such as the sample size and monthly values of suicides, were frequent. The calendar effect was adjusted only in 11 studies. Some recommendations concerning the methodological and reporting issues are summarized for future articles on the seasonal affect on suicides.
Does Legalized Gambling Elevate the Risk of Suicide? An Analysis of U.S. Counties and Metropolitan Areas
Authors: McCleary Richard , Chew Kenneth S.Y. , Merrill Vincent , Napolitano Carol
Published: December 2003

This study addresses a possible link between suicide and casino gambling. Resident suicide rates are analyzed for (a) a 1990 cross‐section of 148 U.S. metropolitan areas and (b) before and after the advent of legalized casinos in five U.S. counties. Data are drawn from government and gaming industry sources. In cross‐section, metro area suicide is strongly correlated with region, accidental death and homicide rates, age and race composition, and economic vitality, followed by a modest net positive correlation with casino presence. By contrast, the time series analysis yields no evidence of a gambling effect.
The Isoinversion Principle—a General Model of Chemical Selectivity
Authors: Buschmann Helmut , Scharf Hans‐Dieter , Hoffmann Norbert , Esser Peter
Published: December 2003

A large number of successful methods for chirality transfer, using either stoichiometric or catalytic chiral auxiliaries, are in use today. However, there is a lack of practical and dynamic selectivity models, i.e. models which take into account the entire reaction sequence, and which allow simple and reliable assessment, optimization and prediction of selectivity in asymmetric syntheses. The models that are available are either too strongly biased to the steric requirement of the particular molecules reacting, but do not go beyond classical considerations of static facial differentiation, or they take a demanding, theoretical approach, which because of its inherent limitations and the great theoretical effort required has not yet found its way into the practical world of the synthetic chemist. The “Isoinversion Principle”, developed on the basis of Eyring's theory, closes this gap. With its aid, the synthetic chemist can determine the characteristic isoinversion temperature Ti for the reaction type of interest from a few temperature‐dependent measurements of selectivity parameters. Ti then affords information on interesting questions such as optimization etc. The advantage of this method is that it is useful not only for stereoselectivity, but for any kind of process where selectivity in general (regio‐,chemo‐, etc) is generated at two or more stages of a reaction sequence, regardless of whether these reactions involve the ground state or a diabatic photoprocess. The present review will demonstrate that this generation of selectivity at two or more stages of a reaction sequence occurs more commonly than is generally thought.
Strained‐Ring and Double‐Bond Systems Consisting of the Group 14 Elements Si, Ge, and Sn
Authors: Tsumuraya Takeshi , Batcheller Scott A. , Masamune Satoru
Published: December 2003

The organometallic chemistry of the Group 14 elements E = Si, Ge, Sn in the 1980's is highlighted by the successful construction and characterization of three systems previously thought to be too reactive to exists: (1) three‐membered ring compounds including cyclotrisilane, cyclotrigermane, and cyclotristannane, (2) molecules containing EE double bonds including disilene, digermene, and distannene, and (3) strained polycycles containing a skeleton of Group 14 elements, such as bicyclo[1.1.0]tetrasilane, hexagemaprismane, and octasilacubane. The majority of these numerous compounds now available are fully substituted with bulky ligands to suppress the reactivity intrinsic to the systems. These compounds permit examinations of (1) the variation of physical and chemical properties of a system with these elements and also with the ligands and (2) how two systems are interrelated thermally and photochemically with the intermediacy of the divalent (carbene‐like) species. Theoretical calculations on virtually all of the parent compounds discussed in this review are evaluated alongside the experimental results. Some polycycles may constitute a stepping‐stone on the way to compounds with a triple bond.
Thermal and Light‐Induced Spin Crossover to a Metastable Low‐Spin State in [Fe(mtz)6](CF3SO3)2
Authors: Gütlich Philipp , Poganiuch Peter
Published: December 2003

Irradiation by red light at T ≲ 40 K induces the transition of the stable high‐spin state of 1 to a metastable low‐spin state, which, at T < 40 K, has a lifetime of days to weeks, The transition occurs via double intersystem crossing, 5T2 → 5E → 3T1 → 1A1. Compound 1 is only the second compound to show this effect.
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A Homogeneous Platinum Catalyst in the Stationary BF3 · H2O Phase for the Hydrogenation of Arenes
Authors: Horváth István T.
Published: December 2003

The advantages of homogeneous and heterogeneous catalytic systems are combined in stationary liquid‐phase catalysts such as the system [PtCl2,(CH3CN)2] in BF3 · H2O on clay or silica supports, which is used here for hydrogenation of arenes. The hydrogenation can be performed under relatively mild conditions, the products are separable by simple filtration, and the hydrogenation proceeds selectively, as shown for a 1 : 1 : 1 : 1 mixture of benzene, toluene, o‐xylene, and 1,2,4‐trimethylbenzene.
A New Economical Process for the Preparation of Silver(I,III) Oxide, AgO
Authors: Kielhorn Sabine , Buß Dieter H. , Glemser Oskar , Gerner Roland , Jeske Gerald
Published: December 2003

SO2/O2 or SO/O2 are the oxidants used to precipitate AgO from AgNO3 solutions at pH 10.5. The yield of Ago is up to 97%. The overall reaction can be formulated as Equation (a).
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Cyclopentadienyl—Actinide Complexes: Bonding and Electronic Structure
Authors: Bursten Bruce E. , Strittmatter Richard J.
Published: December 2003

Shortly after the discovery of ferrocene, Reynolds and Wilkinson demonstrated that actinide elements are capable of forming organometallic compounds containing the cyclopentadienyl (Cp) ligand. The compound they reported, [Cp3UCl], was the first of a host of organoactinide complexes that contain Cp and substituted Cp ligands. In 1968, Streitwieser and Müller‐Westerhoff synthesized uranocene, [(C8H8)2U], a molecule whose existence had been predicted five years earlier by R. D. Fischer. Because uranocene has no analogue in transition‐metal chemistry, its synthesis stimulated new interest in organoactinide chemistry and in comparisons with organotransition‐metal chemistry. Since that time, Cp and substituted Cp ligands, such as pentamethylcyclopentadienyl (Cp*), have become the most important and flexible ligands in actinide organometallic chemistry. In the past 15 years especially, the bonding of Cp ligands to actinide elements has been extensively probed by both experiment and theory. There are both significant similarities and equally significant differences in the bonding of the Cp ligand to the f‐element metals compared to the d‐element metals.
Lipoxins and Related Eicosanoids: Biosynthesis, Biological Properties, and Chemical Synthesis
Authors: Nicolaou K. C. , Ramphal John Y. , Petasis Nicos A. , Serhan Charles N.
Published: December 2003

Among the various enzymes found in human tissues that act on arachidonic acid, there are three major types of lipoxygenases (LO), operating at the 5‐, 12‐, and 15‐positions. The 5‐LO is a key enzyme and plays a central role in the biosynthesis of leukotrienes, which are potent arachidonate‐derived mediators of allergy and inflammation. Because of the importance of the 5‐LO‐derived products in human pathophysiology, studies were initiated to examine the consequences of initial lipoxygenation at C15 of arachidonic acid as well as to probe interactions between the major LO pathways. These studies led to the identification of a new series of biologically active tetraene‐containing eicosanoids termed lipoxins. This article summarizes the isolation, biosynthesis, and chemical synthesis of lipoxins and related systems, and reviews recent results concerning their formation and biological activities. The total synthesis of these molecules based on a new and general synthetic strategy involving palladium catalysis is reviewed. This synthetic approach has allowed the preparation of several types of acyclic eicosanoids in their naturally occurring forms which, in turn, allowed comparisons with naturally derived materials and enabled detailed studies of the biological actions of these biomolecules. Structure–activity relationships were also derived by combining chemical synthesis and biological investigations.
Designed Coupling of C1 Ligands: Organometallic Model Reactions
Authors: Alt Helmut G.
Published: December 2003

With the planned synthesis of thermally stable, mononuclear bis(carbyne) complexes and the subsequent CC coupling of the two carbyne ligands to give an alkyne, F. Filippou et al. have been able to fully confirm the mechanism of C1 + C1‐coupling reactions using tungsten complexes. This mechanism could also play a role in the CC‐coupling reactions of carbonyl‐with carbonyl‐ and of carbonyl‐with isocyanide‐ligands to give the corresponding alkyne ligands (see also Communication on p. 1167ff.).
Novel Building Blocks for the Synthesis of Organic Metals
Authors: Enkelmann Volker
Published: December 2003

To combine individual molecules according to a building‐block system such that the resulting crystals have special electrical, optical or magnetic properties is the fondest wish of many chemists. But even the planned cultivation of crystals with predeterminated structure is still not possible. To achieve high conductivities in charge‐transfer complexes, for example, the donor and acceptor molecules must crystallize in separate stacks with uniform interstack distances. Hünig et al. have developed valuable acceptor molecules, more recently of the inverse Wurster type (aromatic ground state, quinoid oxidized form), which can give fresh impetus to the area of organic metals (Angew. Chem. Int. Ed. Engl. 30 (1991) 561, 563).
A Water‐Complexed Organolithium Compound: [LiCH(CN)2 · H2O · TMEDA]∞
Authors: Lambert Christoph , von Ragué Schleyer Paul , Pieper Ursula , Stalke Dietmar
Published: December 2003

Not the bidentate amine ligand, but water coordinates to the Li cation in [LiCH(CN)2 · H2O · TMEDA]∞ 1 (TMEDA = tetramethylethylenediamine), a very unusual structural characteristic for lithiated organic compounds. Inter‐molecular hydrogen bonds between the H atoms of the aqua ligands and the N atoms of TMEDA are observed. 1 is therefore the first water‐complexed lithiated organic compound derived from a CH acid.
The Phosphorus Ylide CH2PH3 is Stable in the Gas Phase
Authors: Keck Helmut , Kuchen Wilhelm , Tommes Peter , Terlouw Johan K. , Wong Thomas
Published: December 2003

By neutralization–reionization mass spectrometry (NRMS), the parent compound of the phosphorus ylides, methylenephosphorane CH2PH3, can be generated and unequivocally characterized. This substance cannot be “bottled” but is stable under the conditions of the NRMS experiment, and its properties correspond with those proposed by theory.
Alkynyl‐ and Alkenyl(phenyl)iodonium Compounds. New Synthetic Methods (86)
Authors: Stang Peter J.
Published: December 2003

Compounds with highly coordinated, polyvalent main‐group elements represent an interesting alternative to the many well‐known transition‐metal complexes. Among the oldest and best known stable examples of such organic molecules are the iodine(III) compounds. Diaryliodonium species, Ar2IX, for example, have been known for over a hundred years and play an important role in lithography. Likewise, acetylenes and olefins are among the oldest, most important, and most valuable compounds in chemistry. Besides simple hydrocarbon alkenes and alkynes, numerous functionalized derivatives are also known and widely employed in organic chemistry. Despite the ubiquity and prominance of both IIII species and olefins and acetylenes, the combination of these two types of functional groups in a single molecular unit, namely compounds with polyvalent iodine and at least one alkyne or olefin residue, was unknown until recently. The successful preparations of simple alkynyl‐ and alkenyl‐(phenyl)iodonium species during the 1980s has resulted in a renaissance in both acetylene and IIII chemistry. These alkynyliodonium compounds readily undergo nucleophilic substitution on the alkyne moiety (SN‐A reactions) which are difficult with other substrates. The application of a wide variety of nucleophiles in this reaction resulted in diverse functionalized alkynes including previously unknown acetylenic carboxylates, sulfonates, and phosphates. These are excellent substrates for cycloaddition reactions as well as numerous other interesting chemical transformations.
Structures, Structures, and Structures
Authors: Janoschek Rudolf
Published: December 2003

For quantum chemical statements about the stabilities of molecules which serve as incentives for the synthesis of new compounds, a structure determined by calculations according to the state of the art must be identified as corresponding to a minimum on the energy hypersurface. That kinetics must also not be disregarded, is the contribution of Pople et al., reported in this article. Only if the activation barriers surrounding the energy minimum have a certain minimum height, does a minimum structure have the prospect of experimental realization. Therefore, structures should be classified not only according to energy considerations but also from this viewpoint.
C60‐Fullerene—A Playground for Chemical Manipulations on Curved Surfaces and in Cavities**
Authors: Schwarz Helmut
Published: December 2003

Fullerenes—Important Results in Brief could be the title for this highlight which concentrates on the rich and varied chemistry of C60. Numerous examples of the organometallic and organic chemistry of the intact C60 framework as well as the endohedral metal and noble‐gas complexes of fullerenes are briefly discussed. It is quite apparent why the fullerenes are such a hot topic.
Natural Products as Probes of Cellular Function: Studies of Immunophilins
Authors: Rosen Michael K. , Schreiber Stuart L.
Published: December 2003

One of the great mysteries of cell biology remains the mechanism of information transfer, or signaling, through the cytoplasm of the cell. Natural products that inhibit this process offer a unique window into fundamental aspects of cytoplasmic signal transduction, the means by which extracellular molecules influence intracellular events. Thus, natural products chemistry, including organic synthesis, conformational analysis, and methods of structure elucidation, is a powerful tool in the study of cell function. This article traces our understanding of a group of natural products from the finding that they inhibit cytoplasmic signaling to their current recognition as mediators of the interaction between widely distributed protein targets. The emphasis of the discussion is primarily structural. The interactions between the natural‐product ligands and their protein receptors are analyzed at a molecular level in order to shed light on the molecular mechanisms of the biological functions of these compounds. In the process we hope to illustrate the power of chemical analysis as applied to biological systems. Through chemistry we can understand the molecular basis of biological phenomena.
The Electronic Structure of [(η5‐C5H5)2Co2]: Comment on the Existence of a Complex with an Unsupported CoCo Double Bond
Authors: Abrahamson Harmon B. , Niccolai Gerald P. , Heinekey D. Michael , Casey Charles P. , Bursten Bruce E.
Published: December 2003

Bridging hydrido ligands possibly cause the magnetic behavior of the Cp*Co dimer formulated by Schneider et al. as Cp*CoCoCp* (Angew. Chem. Int. Ed. 1992, 30, 1124). This would agree with the calculated electron structures of the model compound CpCoCoCp and the hydrido complexes derived from them. Also the lack of reactivity of the dimer's “naked” CoCo double bond toward CO and ethylene can be explained without difficulty by a stabilizing influence of bridging hydrido ligands. The results of this theoretical study will certainly spark further investigations.
Biochemical Degradation of Cyanamide and Dicyandiamide
Authors: Estermaier Lydia M. , Sieber A. Heidemarie , Lottspeich Friedrich , Matern Dagmar H. M. , Hartmann Guido R.
Published: December 2003

The substrate specificity of enzymes at low catalytic activity is apparently much broader than previously assumed. This conclusion, based on the results of studies of the biochemical degradation of cyanamide and dicyandiamide, also contributes to the understanding of how chemicals not found in nature are metabolized when they are purposely or inadvertently released into the environment. In natural ecosystems the degradation time for these compounds is quite long in comparison to the duration of laboratory experiments. Thus enzymatic reactions such as the urease‐catalyzed hydrolysis of cyanamide (whose calcium salt is used as a fertilizer) may contribute to the degradation of toxic chemicals.
Evidence for [PdSiO] from IR Spectroscopy
Authors: Mehner Thomas , Köppe Ralf , Schnöckel Hansgeorg
Published: December 2003

When Pd atoms are cocondensed with SiO in solid argon onto a helium‐cooled copper surface, [PdSiO] is formed. The IR spectrum and quantum‐mechanical calculations indicate a linear structure in which the Si atom is coordinated directly to the metal (ṽ(PdSiO) = 1246.3, ṽ(PdSi) = 375 cm−1). The bonding situation in PdSiO may be compared with that in transition‐metal carbonyl complexes.
Preparative‐Scale Separation of C60 and C70 on Polystyrene Gel
Authors: Gügel Andreas , Becker Michael , Hammel Dirk , Mindach Lutz , Räder Joachim , Simon Thomas , Wagner Manfred , Müllen Klaus
Published: December 2003

Five grams of a mixture of C60/C70 can be separated in 24 hours by gel permeation chromatography on polystyrene gel. The mobile phase can be completely recovered, and the method can be scaled up by a simple increase in the inner diameter of the column.
The Enchanting Alkaloids of Yuzuriha
Authors: Heathcock Clayton H.
Published: December 2003

The oriental plant Yuzuriha (Daphniphyllum macropodum) elaborates a fascinating family of polycyclic, squalene‐derived alkaloids that provide a test for state‐of‐the‐art methods of organic synthesis. The intriguing structures of these natural products have inspired us to design and explore two rather different approaches for their laboratory synthesis. This article recounts and contrasts these two different syntheses. The first approach was based on a method of synthetic design that emphasizes efficient construction of the polycyclic skeleton of the molecule (Corey's “network analysis”). A strategic bond was identified and the synthesis planned around the late formation of this bond. The synthesis that was designed by this approach proceeded smoothly until the point where it was necessary to remove functional groups that had been incorporated solely for the purpose of forming the strategic bond. Although the problems were eventually overcome, the resulting synthesis was too long and did not control the configuration of one of the stereocenters. The second approach was based on a possible biosynthesis of one of the alkaloids and provided surprisingly easy access to the simpler members of the family. The success of this synthesis led to a concrete proposal about the biosynthesis of the alkaloids and to the discovery of the astonishing transformation depicted in Scheme 27. In this marvelous reaction, an acyclic squalene derivative is converted by successive treatment with ordinary commodity chemicals into a pentacyclic alkaloid. The transformation involves the formation of four carbon–carbon bonds, two carbon‐nitrogen bonds, and one carbon‐hydrogen bond!
Are Denser Packings of Spheres than Closest Packings Possible? How Many Closest Packings of Spheres Exist?
Authors: Müller Ulrich
Published: December 2003

“On the six‐cornered snowflake” is the title of a short work by Johannes Kepler from 1611, in which an arrangement of spheres that is known today as cubic closest packing was first described. The modern term is based on the intuition of whole generations of chemists, physicists, and crystallographers. A rigorous mathematical proof that the maximum space‐filling is really achieved in this packing was provided in 1991 by W. Y. Hsiang. Central to his proof are the domains of influence of the spheres, which can be described by surrounding polyhedrons and which must completely fill the space.
Oxazaborolidines and Dioxaborolidines in Enantioselective Catalysis
Authors: Lohray Braj B. , Bhushan Vidya
Published: December 2003

Enantioselective ketone reductions, allyl additions, and Diels—Alder reactions [for example Eq. (a)] are only a few of the reactions catalyzed by chiral oxazaborolidines and dioxaborolidines, which are sometimes produced in situ. A further application is described by Bringmann and Hartung on p. 761. They used adducts of oxazaborolidines and BH3 for the atropo‐enantioselective ring opening of lactones to obtain rotationally hindered biaryls. These are also becoming more and more important as chiral auxiliaries.
Soft Matter (Nobel Lecture)
Authors: de Gennes Pierre‐Gilles
Published: December 2003

Polymers, tensides, liquid crystals, and colloids have always stood at the forefront of Pierre‐Gilles de Gennes's interests. He obtained the Nobel Prize for Physics in 1991, and his Nobel lecture is a “sentimental journey in the wonderland of soft matter”, which is what he calls complex fluids. In his contribution, de Gennes laid more emphasis on the description of experiments than on theory. Thus he devotes one section to the techniques for making “Janus grains” from hollow glass particles; these grains are microparticles with a polar and an apolar side and have interesting properties for potential applications.
Dynamic Motion in [HFe(CO)4]− Ions as Observed by Mössbauer Spectroscopy—Evidence for Hydride “Tunneling”
Authors: Long Gary J. , Grandjean Fernande , Whitmire Kenton H.
Published: December 2003

The iron atom is moved by up to 0.34 Å from its original position in the anion [HFe(CO4)−] when the temperature is increased. This is suggested by the results of Mössbauer spectroscopy at temperatures from 78 to 280 K on a series of ammonium salts with this anion. The displacement is induced by a movement of the ligands and is in accord with a rapid change of position (“tunneling”) of the hydrido ligands, which makes the four carbonyl ligands equivalent. The Gibbs free energy of activation for the tunneling, determined from the temperature dependence of the displacement of the iron atom, is 29.2 kJ mol−1 for the Et4N+ salt and only 9.7 kJ mol−1 for the Me4N+ salt.
Nitrido Complexes of Transition Metals
Authors: Dehnicke Kurt , Strähle Joachim
Published: December 2003

In the past decade new syntheses and numerous structural determinations have enlivened studies in the still relatively young field of nitrido‐transition‐metal complexes. Aside from the terminal function of the nitrido ligand MN:, this group also occurs as linear μ2‐bridging ligand in symmetric and asymmetric coordination; examples are known with almost right‐angled bridge function; and, finally, it also functions as μ3‐bridging ligand. Accordingly, the fresh impulses given to synthetic chemistry by nitrido complexes are also many‐sided: such complexes are used, inter alia, for the preparation of phosphaniminato and thionitrosyl complexes as well as for the synthesis of metallaheterocycles of the type MN3S2 and MN3P2 with delocalized π‐systems. In technetium chemistry complexes with terminal nitrido group are employed as radiopharmaceuticals, and, owing to the strong trans influence of the MN: group, nitrido complexes of molybdenum are suitable as catalysts in olefin metathesis. Finally, nitrido complexes are also of wide interest in theoretical studies.
Artificial Replication Systems
Authors: Hoffmann Siegfried
Published: December 2003

Replicative information systems were the signal for the departure of Evolution into its biological phase and the leitmotiv for our scientific attempts at its imitation. This research diverted the paths of chemistry into complexity. The latest journeys along these routes taken by the research groups of von Kiedrowski, Orgel, and Rebek cover a wide area and are reported against the panorama of the historical development.