bluuebunny/crossref_metadata_2025 huggingface dataset:
A cluster analysis of retrieval patterns among bibliogrpahic databases
Authors: Yerkey A Neil
Published: June 2007

Searchers of bibliographical databases are faced with a multitude of choices, but very few clues, in developing precise searchy strategies. this sutdy attemps to discover subject patterns and clusters among databases in order to provide clues about differences and similarities among them. Descriptors were taken at random from sev en subject categories in the ERIC thesaurus and used as search terms on Bibliographic Retrieval. Services' CROSS database. The resulting 1,830,312 postings from 54 databases were analyzed in two ways: (1) an Expectation Ratio was computed which allowed ranking databases in order of their relative responses to the subject searches; (2) a cluster analysis was conducted to discover possible subject relationships among databases. The results show five large cclusters: Technology, Life Sciences, Bibliography, Business and Industry, and Education; and 12 well‐defined subclusters. It also shows several dimensions which cut across clusters, such as Research and Social and Economic Enterprise, and Indicates that there are nonobvious similarities and differences among databases which may provide clues to more effective search strategy development.
A note on “scholarliness” and “impact”
Authors: Peritz Bluma C.
Published: June 2007

A moderate bu tconsistent positive correlation was found between the number of citations in a paper and the number of times it is cited. This result refers to a collection of papers published in the American Sociology in 1972 and 1973. The followign variables were controlled: journal, year of publicatiions, subject category of paper, number of authors, and seniority of author. Several explanations of this finding are suggested.
Basics of Videodisc and Optical Disk Technology
Authors: Paris Judith
Published: June 2007

This article outlines basic videodisc and optical disk technology. Both optical and capacitance videodisc technology are described. Optical disk technology as a mass dlgltal image and data storage device Is defined and briefly compared with other established information storage media including magnetic tape and microforms. The article includes a look Into the future of videodisc and optical disk.
Statistical recognition of content terms in general text
Authors: Dillon Martin , Federhart Peggy
Published: June 2007

This article discusses ways to improve the quality of retrieval systems that depend on the use of truncated words or quasi‐word stems as an indexing vocabulary. The problems addressed are the generalizability and stability of discriminant function analysis for selecting good topical terms from terms of relatively high frequency in a database drawn from abstracts of Harris Survey press releases. Results confirm that topical terms can be identified by their statistical properties. Consistently high recall of topical terms under a variety of different conditions implies persistent underlying properties strong enough to resist changes in test environment.
Internationality of the social sciences: Implications for information transfer
Authors: Brittain J. Michael
Published: June 2007

The claims of the social sciences to be of universal interest, value, and use are challenged. Citation data show that there is not a free flow of information across language and national boundaries. The implications for the design of a new generation of library and information services which reflect the communication activities and information requirements of social scientists are considered.
File maintenance of MeSH headings in medline
Authors: Humphrey Susanne M.
Published: June 2007

This article addresses file maintenance of subject headings in the National Library of Medicine's MEDLINE, a bibliographic retrieval file which is indexed using Medical Subject Headings (MeSH), NLM's subject authority. The emphasis is class maintenance in which sets of records in MEDLINE are changed by maintenance actions which reflect yearly changes in MeSH. Specific types of maintenance action are described with examples to highlight problem areas. Class maintenance failures, checking class maintenance, and informing endusers of MeSH changes resulting in class maintenance are discussed. Technical constraints and feasibility are not analyzed in detail; rather, the approach is geared toward requirements and impact of maintenance from the standpoint of vocabulary specialists and end‐users. The article concludes with a brief statement on defining file maintenance policy.
Fair use versus fair return: Copyright legislation and its consequences
Authors: Horowitz Irving Louis , Curtis Mary E.
Published: June 2007

The purpose of this article is to examine the ramifications of legislative recognition of the concept of fair use in the Copyright Act of 1976. The fair use concept, while of small consequence in its normative origins, has turned out to be the foundation of the most perplexing and divisive issues in the new legislative guidelines governing copyright. Legislative recognition of the concept of fair use, coupled with enormous growth of a new technology—extending from xerography to on‐line database systems—creates de facto exemptions to both the intent and content of new copyright guidelines. The issue is not one of limiting use or suppressing information, but of mechanisms for safeguarding the rights of copyright holders, be they authors or publishers, and insuring the free flow of information by providing a proper return on both intellectual creativity and capital expenditures. The authors argue that the elimination, or at least curtailment of fair use doctrine, coupled with an increase in technological approaches to reporting of secondary use of copyrighted material, will benefit all sections of the knowledge industry. Authors will receive proper royalties on use; publishers will be able to sell more books and journals at lower prices; and librarians will be liberated from extensive chores such as monitoring usage or determining fee schedules and transferences. The issue is one of fair return—an issue obscured and ultimately subverted by fair use.
Applications of multidimensional scaling: Comment on “a method for studying intercorrelated circulation patterns in library systems”
Authors: McGrath William E.
Published: June 2007

Applications of multidimensional scaling to library circulation, with implications formanagement decisions in the areas of collection building, housing of collections, allocation of funds, and on‐line retrieval are discussed. As a data‐descriptive, hypothesis‐generating technique, implications for theory building, hypothesis testing, prediction, and explanation are also discussed. Cautions concerning the interpretation of clusters, dimensions, the form of input matrices, and care in the definition of objects submitted to scaling are mentioned.
A drill and practice program for online retrieval
Authors: Boyce Bert R. , Martin David , Francis Barbara , Sievert Mary Ellen
Published: June 2007

DAPPOR, a drill and practice program for online retrieval provides reinforcement to students engaged in learning the basic command protocols of the major vendors of bibliographic databases. The DAPPOR evaluation program overcomes the difficult problems of determining the correctness of a user response in a highly flexible environment. The coding of answer definitions and the process of recursive reduction used by the evaluation program are described.
Information science research: The search for the nature of information
Authors: Kochen Manfred
Published: June 2007

High‐level scientific research in the information sciences is illustrated by a sample of recent discoveries involving the design of information‐processing algorithms, bibliometric scaling, and flows of information in biological systems and in countries. It is pointed out that when the concept of information first assumed an independent identity, the only known information processing systems were biological; now, after four decades of vigorous development of electronic information systems, the search for the essential nature of information is focussing again on biological systems and on sociotechnological systems as well.
Online searching styles: A case‐study‐based model of searching behavior
Authors: Fidel Raya
Published: June 2007

The model of operationalist and conceptualist searching styles describes searching behavior of experienced online searchers. It is based on the systematic observation of five experienced online searchers doing their regular, job‐related searches, and on the analysis of 10 to 13 searches conducted by each of them. Operational‐ist searchers aim at optimal strategles to achleve precise retrieval; they use a large range of system capabilities in their interaction. They preserve the specific meaning of the request, and the aim of their iterations is an answer set representing the request precisely. Conceptualist searchers analyze a request by seeking to fit it into a faceted structure. They first enter the facet that represents the most important aspect of the request. Their search is then centered on retrieving subsets from this primary set by introducing additional facets. In contrast to the operationalists, they are primarily concerned with recall. During the interaction they preserve the faceted structure, but may change the specific meaning of the request. Although not comprehensive, the model aids in recognizing special and individual characteristics of searching behavior which provide explanations of previous research and guidelines for further investigations into the search process.
An investigation of different string coding methods
Authors: Goyal Pankaj
Published: June 2007

This study Investigates various techniques for the automatic coding of English Language strings. The strings are titles drawn from bibliographic files, but the techniques do not require any prior knowledge of the source. Variations of the techniques have also been tested and it has been shown that string abbreviation or coding based on the maximum entropy principle gives the best results. Some of the reasons for the nonuniqueness of the generated codes are presented.
Artificial intelligence: Underlying assumptions and basic objectives
Authors: Cercone Nick , McCalla Gordon
Published: June 2007

Artificial intelligence (AI) research has recently captured media interest and it is fast becoming our newest “hot” technology. AI is an interdisciplinary field which derives from a multiplicity of roots. In this article we present our perspectives on methodological assumptions underlying research efforts in Al. We also discuss the goals (design objectives) of AI across the spectrum of subareas it comprises. We conclude by discussing why there is increased interest in AI and whether current predictions of the future importance of AI are well founded.
Research productivity and breadth of interest of computer scientists
Authors: Subramanyam K.
Published: June 2007

The relationship between research productivity of computer scientists (as indicated by the number of papers published) and the breadth of research interest was investigated. A random sample of 419 authors was drawn from a four‐year cumulative author index of Computer and Control Abstracts. Data on the number of papers published by these authors and the subject dispersion of these papers were also gathered from Computer and Control Abstracts. A moderately strong positive correlation was found between the number of papers published by each author and the number of subfields of computer science in which these papers were published. Research productivity and breadth of research interest of computer scientists appear to be directly related. It also appears that computer scientists have a more diversified research interest within their own field than environmental scientists who tend to work consistently in a well‐defined subfield of their discipline.
Online search patterns: NLM CATLINE database
Authors: Tolle John E. , Hah Sehchang
Published: June 2007

In this article the authors present their analysis of the online search patterns within user searching sessions of the National Library of Medicine ELHILL system and examine the user search patterns on the CATLINE database. In addition to the CATLINE analysis, a comparison is made using data previously analyzed on the MEDLINE database for the same time period, thus offering an opportunity to compare the performance parameters of different databases within the same information system. Data collection covers eight weeks and includes 441, 282 transactions and over 11, 067 user sessions, which accounted for 1680 hours of system usage. The descriptive analysis contained in this report can assist system design activities, while the predictive power of the transaction log analysis methodology may assist the development of real‐time aids.
Person‐to‐person communication in an applied research/service delivery setting
Authors: Salasin John , Cedar Toby
Published: June 2007

Data from a national survey (n = 1666) of researchers, practitioners, and policymakers in the field of rural mental health services were used to conduct a sociometric analysis of person‐to‐person communication in tData from a national survey (n = 1666) of researchers, practitioners, and policymakers in the field of rural mental health services were used to conduct a sociometric analysis of person‐to‐person communication in tData from a national survey (n = 1666) of researchers, practitioners, and policymakers in the field of rural mental health services were used to conduct a sociometric analysis of person‐to‐person communication in the field. This article describes the structure of the person‐to‐person communication network in terms of its connectedness, centrality, homogeneity, and differentiation. Despite the diversity of survey respondents, and apparently meager interorganizational communication, communication in the field is similar, in many respects, to that observed in “invisible colleges.” While the probability of two randomly chosen individuals being in contact is low (0.0008), over 70% were connected indirectly. The person‐to‐person communication network is also highly centralized and exhibits higher than expected communication among respondents in the same professional role, type of work organization, and geographical region. It does not appear to be highly differentiated with respect to topic, since the majority of information providers are contacted with respect to a number of topi While the probability of two randomly chosen individuals being in contact is low (0.0008), over 70% were connected indirectly. The person‐to‐person communication network is also highly centralized and exhibits While the probability of two randomly chosen individuals being in contact is low (0.0008), over 70% were connected indirectly. The person‐to‐person communication network is also highly centralized and exhibits higher than expected communication among respondents in the same professional role, type of work organization, and geographical region. It does not appear to be highly differentiated with respect to topic, since the majority of information providers are contacted with respect to a number of topics.
Information transfer as technical assistance for development
Authors: Dosa Marta L.
Published: June 2007

Policies for development assistance have undergone several changes in recent decades. These changes have affected the information needs in developing countries and the responses of aid agencies. The article outlines trends in assistance strategies and types of international organizations as sources of information transfer. The review concludes with information‐related factors to be considered by technical assistance projects and implications for developing countries.
International cooperation in information systems and services
Authors: Neelameghan A. , Tocatlian J.
Published: June 2007

This article considers information exchange as an essential element in international cooperative arrangements. It examines in some detail the information systems of the United Nations and its specialized agencies and their impact on and contribution to international cooperation. The library, archives, and information programs of Unesco are described. The article considers recent trends observed in the establishment of a global information network, under the auspices of the United Nations, in order to facilitate a more equitable distribution of technological information and promote technical cooperation among developing countries. Certain features of Unesco's regional approach to information network development are reviewed and their advantages are described. The impact, both beneficial and disadvantageous, of information technology on international cooperation in the information area is examined. The special problems faced by developing countries wishing to benefit fully from international (cooperative) information systems are discussed as well as some of the strategies adopted in an effort to find solutions to some of these problems. The authors conclude that in the coming years the transfer of information will have to be considered as a whole encompassing the production, recording, processing, distribution and use of information, the economic aspects of related industries, the sociopolitical and socioeconomic characteristics of the countries participating in a given information system, and the contribution of the information communication industry to the economic development of nations.
An overview of social measures of information
Authors: Menou Michel J.
Published: June 2007

The rise of the information society calls for quantitative and qualitative measures of information activities at the subnational, national, and international levels, which could help us better understand the issues and make sounder decisions. This article reviews recent developments in this direction as they relate to sectoral studies centered around kinds of information, information institutions and services, messages and communication technologies, and to global studies, concerned with the production and consumption of information, social change, information channels, policies and information indices. An account of efforts in the area of information statistics is also given. The present limitations of the various kinds of measures are discussed. It is advocated that consistent, comprehensive, and meaningful information measures need to be compiled regularly, evaluated, and upgraded to properly monitor, interpret, and control the far reaching changes taking place nationally and internationally.
Electronic publishing: The predicament of occasional users in the editorial process
Authors: Standera O. L.
Published: June 2007

The editorial process of electronic publishing including text entry, editing and editorial review, is a source of particular problems for the occasional user. This issue was studied as part of the project Electronic Publishing at the University of CalgThe editorial process of electronic publishing including text entry, editing and editorial review, is a source of particular problems for the occasional user. This issue was studied as part of the project Electronic Publishing at the University of Calgary. 4497 man‐machine actions were evaluated and user performance over five months was monitored with number of actions per error serving as performance indicator. It appears that the relative progress of users expressed as number of actions per error is affected by the amount (both in terms of frequency of use and number of actions) of use and that absolute values of performance are influenced by motivation, temperament and aptitude for specific tasks. Actions have been measured against the sum total of both comprehension and random errors; it has been found that at the level of total errors around 7% casual users attained the proficiency of steady users. The phenomenon of errors caused by abstraction has received special attention demonstrated on the “cut‐and‐paste” function, and six measures are suggested to aid in the human information processing Involv function, and six measures are suggested to aid in the human information processing Involved.
An investigation of online searcher traits and their relationship to search outcome
Authors: Bellardo Trudi
Published: June 2007

This study investigated some attributes of online searchers that were believed to affect the quality of their search results. Subjects were selected from the online searching courses in six library schools. The searching proficiency of the subjects was measured by their performance on two DIALOG searches. Their creativity level was measured using two self‐report inventories; their intelligence level was approximated from their GRE Verbal and Quantitative scores; and their personality traits in regard to masculinity, femininity, and self‐esteem were measured using the Interpersonal Disposition Inventory. The large number of independent, predictor variables were reduced by factor analysis and the derived factors were related to the dependent variable, online searching performance, in a multiple regression analysis. The findings suggest that differences in searching performance can be attributed, to a small degree only, to general verbal and quantitative aptitude, artistic creativity, and to an inclination toward critical and analytical creative thinking. The findings also raise doubts, however, that high intelligence and other attributes cited by writers in the field are necessary for high performance. The notion that searching performance can be predicted by or is dependent upon certain cognitive or personality traits has thus become highly suspect.
Informatics and small computers in Latin America
Authors: Alvarez Jose , Smiley Steven M. , Rohrmann Francisco
Published: June 2007

The microelectronics revolution has opened numerous opportunities for developing countries. This paper highlights some of the potential benefits, as well as some of the more pressing social and legal problems, facing Latin American nations in the area of informatics and small computers. The discussion covers potential uses, the role of central governments, implications for economic development, and transborder data flows. In order to benefit from this technology, Latin American nations must analyze their current situations, strengthen electronic and communications infrastructures, and pinpoint possible sources of conflict and cooperation.
Are there enduring patents?
Authors: Noma Elliot , Olivastro Dominic
Published: June 2007

U.S. patents (and the technology they represent) age and eventually become obsolete. In this diachronous study, the citations by patents in a given year are compared to the number in subsequent years. The major findings are that, even though influential patents remain influential as they age, both highly and infrequently cited patents age at the same rate. This means that citations do not automatically beget more citations, and without this bandwagon effect, no patents are enduring. In addition, the distribution of patents by number of citations received is stable over time (here, in each year they are distributed as a negative binomial).
The personal computer: Missing link to the electronic journal?
Authors: Case Donald
Published: June 2007

Scientific publishing has evolved over three centuries of technological change. It now faces problems that include rapid growth, literature scatter, increasing costs, and excessive delays in publication. This article examines technical solutions to increasing delays and costs and explores new ways of disseminating research information. Noting developments in computer networking and microcomputer applications, the author contends that the widespread use of personal computers will accelerate the development of electronic publishing.
Library/information services and the nation's elderly
Authors: Moore Bessie Boehm , Young Christina Carr
Published: June 2007

The fastest growing segment of the population of the United States is that of persons 65 years and older. These persons have special information needs that can be filled, in part, by library and information services that are targeted to them. The National Commission on Libraries and Information Science (NCLIS) notes an urgency to improve library and information services to the aging now and in preparation for the 30% rise in the over‐age‐65 population expected by the year 2000. The authors discuss the library and information needs of the aging, the current state of services to the aging, and steps taken by NCLIS to call attention to the need for enhancement of these services. Suggestions are given for libraries and service providers to consider for cooperation and collaboration in serving the elderly.
Bibliometric techniques applied to issues management: A case study
Authors: Lancaster F. W. , Lee Ja‐Lih
Published: June 2007

Online data bases can be used to track the growth of the literature on some topic and to follow the diffusion of the topic through data bases of various types. This type of tracking may be valuable in identifying topics likely to become significant socOnline data bases can be used to track the growth of the literature on some topic and to follow the diffusion of the topic through data bases of various types. This type of tracking may be valuable in identifying topics likely to become significant social or technological “issues”; it might therefore become a useful tool in issues management. A case study on the subject of acid rain is describe it might therefore become a useful tool in issues management. A case study on the subject of acid rain is described.
The vertebrate segmentation clock and its role in skeletal birth defects
Authors: Shifley Emily T. , Cole Susan E.
Published: June 2007

The segmental structure of the vertebrate body plan is most evident in the axial skeleton. The regulated generation of somites, a process called somitogenesis, underlies the vertebrate body plan and is crucial for proper skeletal development. A genetic clock regulates this process, controlling the timing of somite development. Molecular evidence for the existence of the segmentation clock was first described in the expression of Notch signaling pathway members, several of which are expressed in a cyclic fashion in the presomitic mesoderm (PSM). The Wnt and fibroblast growth factor (FGF) pathways have also recently been linked to the segmentation clock, suggesting that a complex, interconnected network of three signaling pathways regulates the timing of somitogenesis. Mutations in genes that have been linked to the clock frequently cause abnormal segmentation in model organisms. Additionally, at least two human disorders, spondylocostal dysostosis (SCDO) and Alagille syndrome (AGS), are caused by mutations in Notch pathway genes and exhibit vertebral column defects, suggesting that mutations that disrupt segmentation clock function in humans can cause congenital skeletal defects. Thus, it is clear that the correct, cyclic function of the Notch pathway within the vertebrate segmentation clock is essential for proper somitogenesis. In the future, with a large number of additional cyclic genes recently identified, the complex interactions between the various signaling pathways making up the segmentation clock will be elucidated and refined. Birth Defects Research (Part C) 81:121–133, 2007. © 2007 Wiley‐Liss, Inc.
Science – or not? The status and dynamics of biotechnology
Authors: Buchholz Klaus
Published: June 2007

This review traces the emergence of biotechnology as a new scientific discipline since the 1980s, when it became a major economic force. Significant changes in theoretical perception, research strategies, aims, and experimental methods, mainly in genetic engineering techniques, occurred during this period. The article is based on an analysis of its scientific status over four decades: the 60s and 70s when work in the field proceeded in different disciplines with a low level of coherence and little integration, then a significant change during the 80s and 90s when common approaches and the merging of molecular biology and biochemical engineering created a new discipline. The analysis covers scientific highlights and outstanding technical progress, presenting two studies undertaken by scientific and governmental agencies in Germany and the USA, as well as results of interviews and a questionnaire dealing with the scientific status of biotechnology. Answers to the questionnaire were obtained from internationally known scientists and from young scientists with biotechnology degrees. The results collected trace the transition of biotechnology from heterogeneous specialties and approaches towards a scientific discipline of its own. A hypothesis is put forward suggesting a new common paradigm allowing for a coherent perception the of phenomena observed.
Real estate loan delinquency, property prices and alternative income opportunities
Authors: Brotman Billie Ann
Published: June 2007

Evidence is shown, using US real estate default data from 1987–2004, that high default rates on mortgages are associated with prior period housing prices, rental income, inflation‐adjusted household median income and interest rate fluctuations. This paper investigates the proposition: that the percentage of real estate defaults is a function of alternative income opportunities. Copyright © 2007 John Wiley & Sons, Ltd.
Darstellung perhalogenierter Dimethyldisulfane durch photochemische Reaktion von CSF2 und CSFCI mit Sulfenylbromiden bzw. ‐chloriden
Authors: Haas Alois , Klug Walter
Published: June 2007

CSF2 bzw. CSFCI reagieren unter der Einwirkung von UV‐Licht mit perhalogenierten Sulfenylbromiden (F2BrCSBr und FCIBrCSBr) und ‐chloriden (Cl3−nFnCSCl, n = 1,2,3) in guten Ausbeuten zu den entsprechenden Dimethyldisulfanen. Reaktionsmechanismen werden diskutiert, IR‐ und 19F‐NMR‐Spektren aufgeführt.
Reaktionen CH‐aktiver Verbindungen mit Aziden, XXI. Entformylierende Diazogruppen‐Übertragung — ein neuer Weg zu α‐Diazo‐ketonen, ‐aldehyden und ‐carbonsäureestern
Authors: Regitz Manfred , Menz Felix
Published: June 2007

Methyl‐ und α‐Methylen‐carbonylverbindungen ohne zusätzliche CH‐Aktivierung sind bisher nicht der direkten Diazogruppen‐Übertragung zugänglich. Man gelangt trotzdem zum Ziel, wenn man die Ausgangsverbindungen zunächst mit Ameisensäureester α‐formyliert und erst anschließend mit p‐Toluolsulfonsäure‐azid umsetzt (entformylierende Diazogruppen‐Übertragung). Zur Synthese von Diazomethyl‐ketonen (10a–l) setzt man die stabilen Natriumsalze der β‐Keto‐aldehyde (6) mit p‐Toluolsulfonsäure‐azid in Äthanol um. Bei der Herstellung von Diazoalkyl‐ketonen (13a–e), α‐Diazo‐aldehyden (22a–d) und α‐Diazo‐carbonsäureestern (24a–h) setzt man die freien Formylverbindungen bzw. deren Tautomere in Methylenchlorid/Triäthylamin mit p‐Tosylazid um. Der N2‐Übertragungsmechanismus, der mit der Abspaltung der Formylgruppe gekoppelt ist, wird diskutiert.
Konfigurationszuordnung cis‐trans‐isomerer 1‐Chlor‐2.2‐diaryl‐äthylene über 2‐Chlor‐3‐aryl‐indenone
Authors: Köbrich Gert , Trapp Horst
Published: June 2007

Die in meist ausgezeichneter Ausbeute verlaufende Cyclisierung von 2‐Halogen‐3.3‐diarylacrylsäuren (2) mit Thionylchlorid zu 2‐Halogen‐3‐aryl‐indenonen (3) erlaubt die Strukturzuordnung cis‐trans‐isomerer 1‐Chlor‐2.2‐diaryl‐äthylene (1).
Photochemische Reaktionen, IV. Photochemische Fragmentierungen von β‐Lactamen
Authors: Fischer Martin
Published: June 2007

N‐Aryl‐β‐lactame werden durch UV‐Licht in zwei Bruchstücke gespalten. Die Richtung der Spaltung (A oder B in Formel 1) wird durch die Substituenten in 4‐Stellung bestimmt. Ist das C‐Atom 4 unsubstituiert, so findet man nur Spaltung A zu Keten und Azomethin. Mit zunehmendem Elektronenzug der Substituenten in 4‐Stellung gewinnt Spaltung B an Bedeutung. Die Quantenausbeuten für die Fragmentierungen liegen zwischen 0.01 und 0.04.
Dimere von 1.3‐Diphenyl‐allen und 1.3‐Diphenyl‐propin
Authors: Staab Heinz A. , Kurmeier Hans‐Adolf
Published: June 2007

Für drei aus 1.3‐Diphenyl‐allen (1), 1.3‐Diphenyl‐propin (2) und 2‐Chlor‐1.3‐diphenylpropen (3) entstehende Kohlenwasserstoffe C30H24 (4, 12, 16) wurden chemische Umsetzungen und spektroskopische Untersuchungen zur Strukturaufklärung durchgeführt. — Die Diphenyldibenzylcyclobutane 18 und 22 wurden ausgehend von δ‐Truxin‐ bzw. ϵ‐Truxillsäure dargestellt.
Zur Chemie cyclischer π‐Elektronensysteme, IV. Stabile Chinotropilidene
Authors: Föhlisch Baldur , Bürgle Peter , Krockenberger Dieter
Published: June 2007

Tropon reagiert mit Phosgen unter milden Bedingungen zu Chlortropyliumchlorid (6). Dessen Umsetzung mit Anthron führt zum 10‐Tropyliden‐anthron (12). Als weiteres stabiles Chinotropiliden wurde das 2.6‐Di‐tert.‐butyl‐4‐tropyliden‐cyclohexadien‐(2.5)‐on‐(1) (15) erhalten. Benzanellierte Chinotropilidene entstehen aus Benzotroponen und Anthron.
Zur Kenntnis halogenierter 4.7.8.9‐Tetrahydro‐4.7‐methano‐phthalane, IV. Über die Konfiguration 1.3‐disubstituierter 4.5.6.7.10.10‐Hexachlor‐4.7.8.9‐tetrahydro‐4.7‐methano‐phthalane
Authors: Feichtinger Hans , Linden Hans‐Werner , Singer Hellmut
Published: June 2007

Durch oxydativen Abbau von Telodrin® zur 1.2.3.4.7.7‐Hexachlor‐bicyclo[2.2.1]hepten‐(2)‐dicarbonsäure‐(5.6) (3) wird die endo‐Konfiguration des anellierten 5‐Ringes bewiesen. Weitere ohne Inversion verlaufende nucleophile sowie elektrophile Umsetzungen vom Friedel‐Crafts‐Typ beweisen, daß die beiden Chloratome in 1.3‐Stellung den Wasserstoffatomen in 8‐ und 9‐Stellung entsprechend der Formel 2i gleichgerichtet sind. 1H‐NMR‐Spektroskopische Untersuchungen stützen diese Ergebnisse.
d‐Orbitaleffekte in silicium‐substituierten π‐Elektronensystemen, X. Vertikale Ionisierungsenergien von Alkyl‐ und Silyl‐benzolen
Authors: Bock Hans , Seidl Hans , Fochler Martin
Published: June 2007

Unterschiede in den massenspektroskopisch bestimmten vertikalen Ionisierungsenergien von Alkyl‐ und Silyl‐benzolen C6H5X (X = H, CH3, C(CH3)3, CH2C(CH3)3, Si(CH3)3, CH2Si(CH3)3, CH(Si(CH3)3)3 und CH2C(Si(CH3)3)3) lassen sich mit unterschiedlicher induktiver Polarisation +ISi > +IC sowie zusätzlicher Elektronen‐Rückgabe Si←Cπ interpretieren. Die obersten besetzten Molekülorbitale linearer π‐Elektronensysteme werden von R3C‐, R3Si‐ und R3SiCH2‐Substituenten gleichsinnig beeinflußt.
Synthese von Gramicidin S mit Hilfe der Merrifield‐Methode
Authors: Klostermeyer Henning
Published: June 2007

Val‐Orn(Tos)‐Leu‐D‐Phe‐Pro‐Val‐Orn(Tos)‐Leu‐D‐Phe‐Pro

Abkürzungen nach den Regeln der IUPAC‐IUB‐Commission on Biochem. Nomenclature, Hoppe‐Seyler's Z. physiol. Chem. 348, 256 (1967).

)wurde auf zwei verschiedenen Wegen mit der Merrifield‐Technik aufgebaut. Die Ankondensation der einzelnen Aminosäurereste erfolgte bei der einen Synthese mit Hilfe von Dicyclohexylcarbodiimid, beim Parallelversuch über die N‐Hydroxy‐succinimidester der tert. ‐Butyloxycarbonyl‐aminosäuren. Nur die erste Synthese führte zu einem genügend reinen Material, aus dem nach Cyclisierung und Schutzgruppenabspaltung reines Gramicidin S‐dihydrochlorid‐trihydrat isoliert werden konnte.
Abfangreaktionen kurzlebiger Radikale, V. Zum induzierten radikalischen Zerfall von Azo‐thioäthern und Azosulfonen
Authors: Neumann Wilhelm P. , Lind Heinrich , Alester Gert
Published: June 2007

Azoverbindungen der Typen ArN  NSAr′ (1) und ArN  NSO2Ar′ (6) reagieren rasch und spezifisch mit Stannyl‐Radikalen nach einem Verdrängungsmechanismus (Sr2), wobei Stickstoff, Ar‐Radikalen und Ar′ SSnR3 bzw. Ar′SOOSnR3 entstehen. Andere Radikale (z.B. Thiyl‐ oder Jod‐Radikale) wirken ähnlich stark induzierend, jedoch wenig übersichtlich auf den Zerfall. Galvinoxyl wirkt nur bei 6, nicht aber bei 1. Beide zerfallen nur bei niedriger Konzentration nach der 1. Ordnung, bei höherer tritt, wie nun verständlich, Selbstinduzierung auf. — 6 wird von Triäthylstannyl‐Radikalen auch an der Azogruppe angegriffen, es entsteht N‐Benzolsulfonyl‐N‐triäthylstannyl‐N′‐phenyl‐hydrazin (8). Dessen Reaktionen werden untersucht.
Borimide, IV. Die Reaktion von Borimiden mit Phenylacetylen
Authors: Paetzold Peter I. , Stohr Günter , Maisch Hartmut , Lenz Helmut
Published: June 2007

Pentafluorphenylbor‐[p‐methoxy‐phenylimid], C6F5B  NC6H4OCH3 (1), reagiert mit Phenylacetylen zu 6‐Methoxy‐4‐phenyl‐2‐pentafluorphenyl‐2.1‐borazaronaphthalin (6‐Methoxy‐4‐phenyl‐2‐pentafluorphenyl‐1.2‐benzazaborin) (2). Das gleiche Produkt entsteht erwartungsgemäß auch, wenn man die zur Bereitung von 1 nötige thermische Abspaltung von HCl aus C6F5B(NHC6H4OCH3)Cl in Gegenwart von Phenylacetylen ausführt. Bei Zusatz von Triäthylamin erhält man nicht 2, sondern unter Substitution von Chlorid am Boramidchlorid durch die Phenylacetylid‐Gruppe das zu 2 isomere Pentafluorphenylborphenylacetylid‐p‐anisidid, C6F5B(C2C6H5)(NHC6H4OCH3) (6). Aus vier Arylboridchlorid‐Arylaminen Ar′BCl2 · H2NAr, bei denen die entsprechenden Borimide nicht bekannt sind, wurden in Gegenwart von Phenylacetylen 2 Mol HCl abgespalten und dabei in guten Ausbeuten entsprechende 2.1‐Borazaronaphthaline (1.2‐Benzazaborine) (7–10) erhalten.
Über Verbindungen mit Urotropin‐Struktur, XLI. Ringschlußreaktionen ausgehend von Cyclooctadien‐(1.5)
Authors: Stetter Hermann , Meissner Hans‐Jürgen , Last Wolf‐Dieter
Published: June 2007

Durch Quecksilberacetat‐Addition an Cyclooctadien‐(1.5) (1) wurde 2.6‐Bis‐[acetoxymercuri]‐9‐oxa‐bicyclo[3.3.1]nonan (2) erhalten, aus dem durch Austausch des Quecksilber‐Restes gegen Jod und anschließende Dehydrohalogenierung 9‐Oxa‐bicyclo[3.3.1]nonadien‐(2.6) (6) entstand. Die Quecksilberacetat‐Addition an dieses Dien ergab 4.8‐Bis‐[acetoxymercuri]‐2.6‐dioxa‐adamantan (7), das in 2.6‐Dioxa‐adamantan (9) selbst übergeführt werden konnte. Die Schwefeldichlorid‐Addition an das Dien führte zum 4.8‐Dichlor‐2‐oxa‐6‐thia‐adamantan (10), aus dem 2‐Oxa‐6‐thia‐adamantan (11) hergestellt wurde.
Umsetzungen mit 1‐Nitro‐2‐dimethylamino‐äthylen, IV. Darstellung von Nitro‐merocyaninen
Authors: Severin Theodor , Böhme Hans‐Jochen
Published: June 2007

Heterocyclen mit aktivierter Methylgruppe lassen sich mit 1‐Nitro‐2‐dimethylamino‐äthylen und seinen Derivaten unter Abspaltung von Dimethylamin zu Nitro‐merocyaninen kondensieren.
Die thermische Zersetzung von Mangancarbonyl
Authors: Lux Hermann , Ignatowicz Anita
Published: June 2007

Die thermische Zersetzung von Mn2(CO)10 im Hochvakuum bei 260–500° führt zu flächenzentriert kubischem Manganoxidcarbid. Aus diesem entstehen bei 600–1000° im Hochvakuum oder im Wasserstoffstrom MnO, α‐ oder β‐Mn, Mn5C2, Mn23C6 und weitere unbekannte Carbidphasen. Als Sublimat erscheint eine bisher nicht beschriebene Modifikation des Mangans.
Die Addition aromatischer Isocyanate an N‐substituierte Amidine
Authors: Richter Reinhard
Published: June 2007

Aromatische Isocyanate lagern sich an die CN‐Doppelbindung vollständig substituierter Amidine im Verhältnis 2:1 zu Hexahydro‐s‐triazin‐Derivaten an.
Aktivierung organischer Verbindungen durch Einführung von Übergangsmetallatomen, IV. Dimerisierung von Ketiminogruppen über Ketimino‐Übergangsmetallverbindungen
Authors: Kauffmann Thomas , Berger Dieter
Published: June 2007

Ketimin‐magnesiumhalogenide, die bekanntlich bei der Einwirkung von Grignard‐Verbindungen auf Nitrile entstehen, wurden durch Umsetzung in THF/Diäthyläther mit CuCl (bei 20–35°) und anschließende Einwirkung von Sauerstoff (bei 20–40°) in die entsprechenden Ketazine übergeführt. Diese Dimerisierung von Ketiminogruppen, die über Ketimino‐Kupferverbindungen verlaufen dürfte – und somit der Dimerisierung von Acetylenresten über Kupferacetylide analog ist – scheint in der Regel nahezu quantitativ zu erfolgen. Am Beispiel des Benzophenonimin‐magnesiumbromids wurde gezeigt, daß bei Anwendung einer katalytischen Menge (0.05 Moläquiv.) CuCl die Ketazin‐Ausbeute besser ist (94%) als bei Anwendung einer äquimolaren Menge (72%). Analoge Dimerisierungen konnten am Beispiel des Benzophenonimin‐magnesiumbromids auch mit CuCl2 (33%), CuCl2/O2 (71%), FeCl3/O2 (61%) sowie in geringem Maße mit CoCl2/O2 und AgNO3 erzielt werden.
Photochemie kleiner Ringe, 6. Eine neuartige Photofragmentierung von Bicyclo[3.1.0]hexenolen
Authors: Dürr Heinz
Published: June 2007

Die Strukturen der als Ausgangsprodukte für die Photofragmentierung verwandten Dialkyldiaryl‐ bzw. Tetraaryl‐bicyclo[3.1.0]hexen‐(2)‐ole‐(4) 2a–d und des Acetoxy‐tetraphenyl‐bicyclo[3.1.0]hexens‐(2) (2a‐Acetat) werden mit Hilfe der NMR‐Spektroskopie zugeordnet. Die Photolyse von 2a–d, 2a‐Acetat führt zu tetrasubstituierten Cyclopentenen (3a–c und 4a, b), zu tetrasubstituierten Benzolen (6a, b) und zum Cyclopentaphenanthren 5a, deren Struktur chemisch sowie massenspektroskopisch bewiesen wird. Für die Photofragmentierung, die über eine π→π

Hierauf wird in einer gesonderten Arbeit näher eingegangen werden.

‐Anregung verlaufen dürfte, wird ein radikalischer Mechanismus vorgeschlagen.
Selenophosphororganische Verbindungen, II
Authors: Petragnani Nicola , Toscano Vicente G. , de Moura Campos Marcello
Published: June 2007

Diphenylselenophosphinsäure‐Se‐phenylester (4) wird nach sechs neuen Methoden dargestellt. Der bisher unbekannte Triselenophosphorsäure‐Se.Se.Se‐triphenylester (8) läßt sich durch Umsetzung von Selenophenol mit PCl3 gewinnen. Die Selenophosphorsäure‐O.O‐dialkylester‐Se‐phenylester 10 erhält man aus Benzolselenylbromid mit Trialkylphosphiten 9 oder Dialkoxyphosphorylquecksilberchloriden 11.
Umsetzungen von Cyclopentadienonen mit aliphatischen Diazoverbindungen, V. Versuche mit 2.3.4.5‐Tetraphenyl‐cyclopentadienon und anellierten Cyclopentadienonen
Authors: Eistert Bernd , Müller Reiner , Thommen Arackal Joseph
Published: June 2007

„Tetracyclon”︁ 5 liefert, als Suspension in methanol. Kaliumhydroxidlösung mit äther. Diazomethanlösung umgesetzt, hohe Ausbeuten an Epoxid 3 neben Pyrazolin 2a. – Mit Diazoäthan wurden aus 5 und aus„Phencyclon”︁ 13 je nach den Reaktionsbedingungen Pyrazoline (1b, 2b bzw. 10 b, 11 b) und Phenole (4 b bzw. 15) erhalten. Mit Diazoessigester/AlCl3 bilden 5, 13 und das„Acecyclon”︁ 19 unter Ringerweiterung die entsprechenden Salicylsäureester 6, 14 bzw. 22. Mit Diazoessigester und Methanol/Kupferpulver entstand aus 5 das aldolartige Umsetzungsprodukt 8, aus 13 dagegen das Ringerweiterungsprodukt 16. – 19 vermag auch 1 Mol. Phenyldiazomethan (zum Pyrazolin 18) und sogar 2 Moll. Diazomethan (zum Bis‐pyrazolin 23) zu addieren. –Die Reaktionsfolgen 13→14 bzw. 13→15 und 19→22 bieten einen neuen Zugang zur Triphenylen‐ bzw. Fluoranthen‐Reihe.
Reaktionen an Indolderivaten, VIII. Die partiell stereoselektive Totalsynthese von DL‐Akuammigin und DL‐Tetrahydroalstonin
Authors: Winterfeldt Ekkehard , Radunz Hans , Korth Tilmann
Published: June 2007

Die partiell stereoselektive Totalsynthese der heterocyclischen Indolalkaloide mit cis‐Verknüpfung der Ringe DE gelingt ausgehend vom α.β‐ungesättigten Keton 5.
Über α‐Halogenäther, XXXIX. Acidolyse und Halogenierung von α‐Alkoxy‐enolphosphaten
Authors: Groß Hans , Freiberg Jürgen
Published: June 2007

Bei der Umsetzung von α‐Alkoxy‐enolphosphaten (6) mit HCl entsteht Dimethylphosphat und der der Enolkomponente entsprechende α.α‐Dichlor‐äther (8). Bei dieser Umsetzung sowie bei der Reaktion von 6 mit Chlor entstehen primär definierte, aber unterschiedlich stabile Orthoesterderivate vom Typ 7.
α‐Metallierung von Bromkohlenwasserstoffen durch Dichlormethyllithium
Authors: Köbrich Gert , Fischer Rolf Hartmuth
Published: June 2007

Dichlormethyllithium überführt Di‐ und Tribrommethan, Benzylidendibromid, 9‐Brommethylen‐fluoren und 1‐Brom‐2.2‐diphenyl‐äthylen unter – im letztgenannten Falle reversibler – Metallierung in die zugehörigen, bei tiefer Temperatur stabilen Bromcarbenoide. Der Vorzug der Metallierung gegenüber dem sonst mit Lithiumorganylen vorrangigen Brom/Lithium‐Austausch wird auf die geringere Basizität des Dichlormethyllithiums zurückgeführt.
Synthese von 2α‐Methoxycarbonyl‐A‐nor‐lupan
Authors: Kundu Samar K. , Chatterjee Asima , Rao A. Somasekar
Published: June 2007

2α‐Methoxycarbonyl‐A‐nor‐lupan (1b) wurde aus Lupeol synthetisiert. Einige Verbindungen, die mehr als eine Sauerstoff‐Funktion im Ring A von Lupan tragen, wurden ebenfalls dargestellt.
Potentielle Cytostatica, XVI. Bicyclische Systeme aus Acetessigester und 5‐Amino‐1‐methyl‐, 5‐Amino‐1‐benzyl‐ sowie 3(5)‐Amino‐pyrazol
Authors: Dorn Helmut , Zubek Alfred
Published: June 2007

Acetessigester liefert mit 5‐Amino‐1‐methyl‐ (1b) bzw. 5‐Amino‐1‐benzyl‐pyrazol (1c) die Pyrazolo[3.4‐b]pyridine 6b 6c. Die Substituentenverteilung in 6 wird durch Isolierung und Cyclisierung der primär entstehenden β‐Amino‐crotonsäureester 5 ermittelt, NMR‐ und IR‐Spektren werden diskutiert. Die Struktur von 1c, das über sein 4‐Äthoxycarbonyl‐Derivat (20b) gewonnen wird, folgt aus dem Vergleich der Kopplungskonstante J3,4 von 1c mit denen strukturell festgelegter Verbindungen. Aus der Größe der Kopplungskonstante der CH‐Protonen kann geschlossen werden, daß 3(5)‐Amino‐pyrazol vorwiegend in der Form 1a existiert. Aus 1a und Acetessigester entsteht 7‐Hydroxy‐5‐methyl‐pyrazolo[1.5‐a]pyrimidin (12). Die Cyclisierung des aus Acetessigester und 1a bzw. 5‐Amino‐1‐p‐toluolsulfonyl‐pyrazol hergestellten β‐Amino‐crotonsäureesters 5a bzw. 10 ergibt ebenfalls 12 und kein 4‐Hydroxy‐6‐methyl‐1H‐pyrazolo[3.4‐b]pyridin (6a). wird durch Debenzylierung von 6c synthetisiert. 3, 4 und 7 sind Purin‐Antagonisten.
Die Dampfphasenhydrolyse von Lanthaniden(III)‐chloriden, 2. Wärmetönung und Gibbs‐Energie der Reaktion DyCl3(f) + H2O (g) ⇌ DyOCl(f) +2HCl(g) Wärmetönung der polymorphen Umwandlung β‐DyCl3 → γ‐DyCl3
Authors: Weigel Fritz , Wishnevsky Victor
Published: June 2007

Mit Hilfe einer Halbmikromethode wird die Dampfphasenhydrolyse des Dysprosium(III)‐chlorids in Abhängigkeit von der Temperatur gemessen. Aus den Hydrolysedaten und parallel dazu ausgeführten Röntgenuntersuchungen wird auf die Existenz zweier polymorpher Modifikationen des DyCl3 geschlossen und damit ältere Befunde von Bommer und Hohmann bestätigt. Die Bildungsenthalpie von Dysprosium(III)‐oxidchlorid wird zu ΔH = –234.3 bzw. –234.7 kcal/Mol gefunden, für die Wärmetönung der Transformation β‐DyCl3 → γ‐DyCl3 ergab sich ein Wert von 2.6 kcal/Mol.
Zur Chemie der FCS‐Verbindungen, 2. Perhalogenierte Sulfenylcarboxylate
Authors: Haas Alois , Oh Dong Young
Published: June 2007

Umsetzungen von Cl3−nFnCSCl (n = 1,2,3) mit F3CCO2Ag liefern in guten Ausbeuten Verbindungen vom Typ , die bei 20° unbegrenzt haltbar sind. Erhitzt man (1) im Bombenrohr auf 170°, so bilden sich Kohlendioxid und F3CSCF3, während beim Bestrahlen mit UV‐Licht Perfluoracetanhydrid, F3CSSCF3 und F3CSO2SCF3 entstehen. Bestrahlt man mit (2) UV‐Licht, so bilden sich CO2 und Cl2FCSCF3. Aus Thionylchlorid und Cl3−nFnCCO2Ag (n = 2,3) konnten nur die entsprechenden Anhydride und SO2 isoliert werden. Analog liefert Silberperfluorbutyrat mit F3CSCl die Zersetzungsprodukte F3CSSCF3, F3CSO2SCF3 und (C3F7CO)2O.
Über die Ringisomerisierung von Flavonen, III. Die Synthese des Eupatorins, eines Flavons aus Eupatorium semiserratum DC
Authors: Farkas Lorand , Strelisky János , Vermes Borbála
Published: June 2007

5.3′‐Dihydroxy‐6.7.4′‐trimethoxy‐flavon (1a) wurde auf zwei Wegen, durch alkalische Ringisomerisierung der entsprechenden 5.7.8‐substituierten Verbindung und nach der Baker‐Venkataraman‐Umlagerung synthetisiert. Dieses war mit dem aus Eupatorium semiserratum isolierten Flavon Eupatorin identisch.
Rubromycine, II
Authors: Brockmann Hans , Lenk Werner , Schwantje Gerd , Zeeck Axel
Published: June 2007

Die Isolierung der roten Antibiotica β‐Rubromycin und γ‐Rubromycin wird beschrieben. – β‐Rubromycin isomerisiert sich in siedendem Pyridin quantitativ zu α‐Rubromycin und wird durch verd. Mineralsäuren unter Verseifung eines Methoxyls in γ‐Rubromycin verwandelt. γ‐iso‐Rubromycin entsteht: 1. Aus γ‐Rubromycin durch Erhitzen mit Pyridin oder konz. Schwefelsäure, 2. aus α‐Rubromycin durch Chlorwasserstoff in Chloroform. – β‐Rubromycin (11) enthält als Chromophor 8‐Hydroxy‐5.7‐dimethoxy‐naphthochinon‐(1.2), das über Sauerstoff an C‐4 und eine Methylengruppe an C‐3 mit dem Rest des Moleküls verbunden ist. – Chromophor der drei anderen Rubromycine (12, 13, 14a) ist 5.8‐Dihydroxy‐2(bzw. 7)‐methoxy‐naphthochinon‐(1.4) – in α‐Rubromycin am 5‐Hydroxyl methyliert –, an dem über Sauerstoff an C‐7 (bzw. C‐2) und Kohlenstoff an C‐6 (bzw. C‐3) der Rest des Moleküls hängt.