摘要:

Jay S. Siegel is Professor and Co-director of the Organic Chemistry Institute of the University of Zurich and Director of its laboratory for process chemistry research. He has been a member of theOrganic & Biomolecular ChemistryEditorial Board since the journal began and is currently Chair of the Editorial Board. Born in California in 1959, Jay received his BSc degree from California State University, Northridge. He continued his studies in chemistry at Princeton with Professor Kurt Martin Mislow earning both MSc and PhD degrees in the area of Structural Chemistry and Stereochemistry before undertaking a NSF-CNRS postdoctoral fellowship with Jean-Marie Lehn at the University of Louis Pasteur in Strasbourg. He began his independent career as Assistant Professor of Chemistry in 1986 at UCSD, was promoted to Associate Professor in 1992 and Full Professor in 1996. He was named a US-NSF Presidential Young Investigator in 1988, an American Cancer Society Jr. Fellow in 1990, an Alfred P. Sloan Fellow in 1992, and an Arthur C. Cope Scholar by the ACS in 1998. His research interests focus on the synthesis and stereochemistry of designed molecular architectures.2006 was a very successful year forOrganic & Biomolecular Chemistry(OBC); a success that we intend to build on during this year. We would like to thank all of our authors, referees, Editorial and Advisory Board members for all their support and hard work in ensuring thatOBCremains such a good quality journal. We look forward to your continued support in 2007.Throughout 2007, we will be looking to publish even more of your best and most exciting research work in organic chemistry. Such timely research demands a responsive, rapid review and production service so that your latest results appear as soon as possible.OBCremains proud of its rapid times to publication, which continue to be very competitive. Typical times to publication average 43 days for communications and just 65 days for full papers.ISI® impact factors provide an indication of a journal's prominence: revised annually, they take into account the number of citations in a given year for all the citeable documents published within a journal in the preceding two years. Impact factors released in June 2006 showed an impressive 16% rise forOBC(2.55), substantially more than the respectable average increase of over 10% for RSC Journals in general.We strive to makeOBCa great place to publish hot science of current and topical interest. The immediacy index reflects this as the ratio of the number of citations to the number of articles in a given year. The RSC immediacy index (0.79) in combination withOBC's ever increasing prominence supports our commitment to becoming organic chemistry’s best address for announcing new and exciting research.

ISSN:1477-0520    

DOI:10.1039/b616180b

出版商:RSC    

年代:2006

数据来源: RSC

摘要:

More papers and greater impactBuilding on the success achieved in its first five years of publication, 2008 was another superb year forOrganic & Biomolecular Chemistry(OBC). The journal's impressive upward trend in ISI® impact factor to 3.17 coupled with rapid publication times reinforcesOBC’s position as the journal of choice.OBCis now known for publishing the very best synthetic, physical and biomolecular organic chemistry.In 2008, the number of submissions toOBCrose by almost 20% compared to 2007, a clear indication of our great service to authors and the quality of the journal. We would like to thank all our authors, reviewers, editorial and advisory board members for their continued and ever-growing support.Across RSC Publishing, we are working with more authors than ever before—2008 saw the number of authors publishing in RSC Journals increase by 30%. Titles across the collection recorded impressive rises in impact factors, and the latest immediacy indices confirm the relevance and topicality of research published by the RSC.RSC Publishing is committed to providing a world-class publishing service and global visibility to its authors. With the number of citations increasing and immediacy and impact factors rising, it is clear to see thatOBCand RSC Publishing are recognised by researchers worldwide as key resources for publishing and reading the very best research.

ISSN:1477-0520    

DOI:10.1039/b819814b

出版商:RSC    

年代:2008

数据来源: RSC

摘要:

Marc Greenberg received his BS in Chemistry from New York University and BE in Chemical Engineering from The Cooper Union School of Engineering in 1982. He carried out undergraduate research with Professor David Schuster at N.Y.U. and Dr Stanley Seltzer at Brookhaven National Laboratory. After receiving his PhD from Yale University in 1988 under the guidance of Professor Jerome A. Berson, he carried out postdoctoral research as an American Cancer Society fellow with Professor Peter B. Dervan at the California Institute of Technology. He began his independent career in 1990 at Colorado State University and moved to Johns Hopkins University in 2002 where he is a Professor of Chemistry.

ISSN:1477-0520    

DOI:10.1039/b612729k

出版商:RSC    

年代:2006

数据来源: RSC

摘要:

Tom ButlerTom Butler received his B.S. degree at Cal State, Chico under the direction of Prof. David B. Ball. He arrived at UCSB in late 2004 and joined the research group of Prof. Bruce Lipshutz, where early work on nickel-on-graphite had begun. After completing this study on its use for heterogeneous reductions of aryl sulfonates, he spent considerable time and effort developing new technology for controlling regiochemistry in Negishi carboaluminations, and a process for applying this chemistry towards the industrial production of coenzyme Q10. Most recently, he has completed his studies on Ni/Cgas a catalyst for carbon–carbon bond formations and is employed at Gilead.

ISSN:1477-0520    

DOI:10.1039/b714600k

出版商:RSC    

年代:2007

数据来源: RSC

摘要:

Paul van Swieten (1977) is currently in the last year of his PhD research under the guidance of Herman Overkleeft at Leiden University. His thesis elaborates on the development of chemical proteomics techniques for the study of selected protein families, with a special focus on proteolytic activities.

ISSN:1477-0520    

DOI:10.1039/b412558d

出版商:RSC    

年代:2004

数据来源: RSC

摘要:

Great content and great impactOBChas shown continued strong growth in 2009. Submissions of high quality rose by over 20% which allowed the number of articles published to rise by almost the same percentage. We believe that these figures indicate clearlyOBC's attractiveness to the world's top organic chemists. We would like to thank all our authors, referees, and Editorial and Advisory Board members for their continued support.The Editorial Staff onOBCis equally committed to providing great service to our author/reader base. In particular we pride ourselves on our independent and rigorous peer review system, which rests on all of you. We rely on your support throughout 2010 to makeOBCeven better. Feedback from you as readers, authors and reviewers allows us to improve the service we offer to the organic chemistry community. Please send your comments to theOBCeditorial office.The Editorial Board and Editorial Team alike were delighted whenOBC's ISI®impact factor of 3.55 was announced.Thomson ISI Impact factor for 2008This statistic reflects the journal's continued strength and prominence in the field and emphasisesOBC’s position as the journal of choice.

ISSN:1477-0520    

DOI:10.1039/b923743g

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Ali TavassoliAli is a lecturer in chemical biology at The University of Southampton. He is the recipient of the European Association for Chemical and Molecular Sciences' silver medal for European Young Chemist, and a Career Establishment Award from Cancer Research UK. He has a multidisciplinary background in synthetic chemistry and molecular biology. His lab's research interests are at the interface of chemistry and biology; developing high throughput tools, screening methodologies and uncovering compounds that tackle diseases through inhibition of specific protein-protein interactions. They are also active in the new field of synthetic biology. For more information see the Tavassoli group website.

ISSN:1477-0520    

DOI:10.1039/b913300n

出版商:RSC    

年代:2009

数据来源: RSC

摘要:

Ryo AmemiyaRyo Amemiya is an assistant professor at Tohoku University. He was born in Yamanashi in 1976, and received his BSc degree (1999) from Health Sciences University of Hokkaido. He received his MSc. (2001) and PhD degrees (2006) from Tohoku University. In 2002, he was appointed an assistant professor in the Graduate School of Pharmaceutical Sciences, Tohoku University. His research interests are in the area of organometallic chemistry and functionally interesting compounds.

ISSN:1477-0520    

DOI:10.1039/b713700a

出版商:RSC    

年代:2007

数据来源: RSC

ISSN:1477-0520    

DOI:10.1039/b819155g

出版商:RSC    

年代:2008

数据来源: RSC

摘要:

The design of nanomechanical devicesviaa bottom-up approach, elegantly illustrated in the recent examples of molecular machines,1demands for new synthetic methodology to construct such complex molecular systems. Accordingly, we have focused on the development of molecular switches and motors based on sterically overcrowded alkenes.2Besides the challenge to synthesize these highly overcrowded alkenes, control of steric hindrance at the central olefinic bond is a crucial parameter for the motor function. A key feature of the light-driven molecular motors is that they are capable of repeated unidirectional rotation around their central double bond functioning as the axis of rotation. This rotation takes place in four steps as two photoisomerization steps are each followed by a thermal helix inversion step.3However, in the so-called first generation of this type of molecules the rate determining thermal isomerization steps are slow at room temperature. The replacement of the two six-membered rings of the original molecular motor by two five-membered rings in1led to a significant increase of the speed of rotation due to a decrease in steric hindrance.4In this paper we present new methodology to prepare sterically overcrowded alkenes2, with distinct upper and lower halves and which contain in the upper half a five-membered ring bearing the stereocentre needed to control the direction of rotation (Fig. 1).Molecular motors1and2containing either one or two five-membered rings with a stereocentre.Where most olefination reactions fail to provide such severely hindered molecules we rely on the diazo–thioketone coupling, more commonly referred to as the Barton–Kellogg5,6reaction, to prepare sterically overcrowded alkenes. The reaction was introduced in 1920 by Staudinger7and intensively used in the group of Schönberg.8The power of this method is that steric strain is gradually introduced into the molecule in a two fold extrusion process.9In the first step of the reaction, a diazo compound and a thioketone react in a 1,3-dipolar cycloaddition in which a thiadiazoline is formed. In most cases this thiadiazoline is thermally unstable and rapidly eliminates nitrogen to form an episulfide. Extrusion of the remaining sulfur atom is then performed by reaction with copper powder or triphenylphosphine to yield the desired alkene. It was established that the elimination of nitrogen in the thiadiazoline was followed by a conrotatory ring closure to form the corresponding episulfide.6Apart from the effectiveness in olefin formation due to the gradual build-up of steric hindrance in the molecule, a major advantage of the reaction is the selective coupling of two non-identical halves which is not easily accomplished with, for example, the McMurry reaction. Of major importance for the development of functionalized molecular motors and switches is the tolerance of the olefination reaction towards a variety of functional groups.10However, the diazo–thioketone coupling method for the preparation of target structures2, starting from hydrazone4and thioketones7, failed to provide any of the desired episulfides8(Scheme 1). We found that the approach we commonly use for similar compounds employing silver(i) oxide as the oxidant was not successful.11,12This prompted an investigation of other oxidizing agents. Based on earlier investigations, the use of hypervalent iodine compounds13such as5seemed to be particularly promising.14Only recently, similar hypervalent iodine reagents have attracted conderable interest in a number of synthetic applications.15Indeed, reaction at low temperature (−50 °C) in DMF resulted in formation of the diazo compound6, as was deduced from the slightly red color of the solution. Upon addition of thioxanthone7a(Y = O), the evolution of nitrogen gas was observed and after workup episulfide8a(Y = O) was obtained in good yield. To extend the scope of the reaction and to test the applicability of reagent5, various thioketones7a–gwere used in the coupling reaction. Moderate to excellent yields were obtained for the various episulfides, as depicted inTable 1.Episulfides8a–gand alkenes2a–gYR8Yield (%)2Yield (%)Isolated yields, see ref.17.OHa63a87SHb58b87C(CH3)2Hc79c90CH&z.dbd;CHHd44d81—He48e81OOMef89f82SNO2g63g87The modified diazo–thioketone coupling for the synthesis of overcrowded alkenes.Desulfurization of the episulfides8was performed preferably by reaction with excess triphenylphosphine in refluxingp-xylene. Although the desulfurization of episulfide8acould be performed with copper powder, removal of the side products could only be achieved with considerable effort. Much more convenient was the use of triphenylphosphine, which cleanly converted the episulfides8a–gto the corresponding alkenes. In case of alkenes2a,2b,2cand2dit was impossible to separate the excess triphenylphosphine by column chromatography. In order to facilitate the purification of these alkenes, this crude reaction mixture was stirred overnight in the presence of excess methyl iodide inp-xylene. Despite the additional reaction with methyl iodide, the reaction sequence was efficient and the conversion of the episulfides to the corresponding alkenes proceeded in all cases in yields exceeding 80%. Surprisingly, the episulfides8a–8dwere obtained as single isomers. To determine the actual structure of the isomer obtained in the stereoselective diazo–thioketone coupling, crystals suitable for X-ray crystallographic analysis were grown by slow diffusion of acetonitrile into a solution of8ain chloroform (Fig. 1andFig. 2).16PLUTO drawing of episulfide8a.It is evident from the structure shown that the methyl substituent and the naphthalene moiety are oriented in the same direction in order to diminish the steric strain in the molecule. Although thesyn-orientation of the sulfur atom with respect to the methyl substituent might be surprising, this is a direct consequence of the reaction mechanism shown inScheme 2.In the first step of the reaction sequence (Scheme 2), the diazo compound6reacts in a 1,3-dipolar cycloaddition with thioketone7a. Although there could be a stereochemical preference in this reaction it is anticipated that two isomeric thiadiazolines9are formed. These thiadiazolines are thermally unstable and even at low temperatures nitrogen evolution is observed, to form a thiocarbonyl ylide10. Since the methyl substituent blocks ring closure on one side of the molecule of the essentially flat thiocarbonyl ylide moiety, a single isomer of episulfide8ais formed.Reaction of diazo compound6and thioketone7ato form episulfide8aviathe intermediacy of thiadiazoline9and thiocarbonyl ylide10.Although further optimization of the reaction conditions might be achieved, these results represent a major advance in the synthesis of overcrowded alkenes and molecular motors. There are two important advantages of this procedure over the McMurry reaction. First of all, this procedure allows selective coupling of different upper and lower halves without formation of homocoupled products. This is not only more efficient from a synthetic point of view, but also facilitates purification of the desired products. Secondly, many substituted thioketones are available, which allows selective functionalization of the desired motor molecules with substituents that would not have been tolerated by the McMurry reaction. In conclusion, this new method not only allows the synthesis of new molecular motors, but is also highly efficient in the construction of severely hindered non-symmetric alkenes.Financial support from the Netherlands Foundation for Scientific Research (NWO-CW, MKJtW), the Basque Country Government (JV), and the EU Project on Molecular Level Devices and Machines HPRN-CT-2000-00029 (SGD) is gratefully acknowledged.

ISSN:1477-0520    

DOI:10.1039/b414959a

出版商:RSC    

年代:2004

数据来源: RSC