@article{FabianKunzMuelleretal.2013, author = {Fabian, Benjamin and Kunz, Steffen and M{\"u}ller, Sebastian and G{\"u}nther, Oliver}, title = {Secure federation of semantic information services}, series = {Decision support systems : DSS ; the international journal}, volume = {55}, journal = {Decision support systems : DSS ; the international journal}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0167-9236}, doi = {10.1016/j.dss.2012.05.049}, pages = {385 -- 398}, year = {2013}, abstract = {fundamental challenge for product-lifecycle management in collaborative value networks is to utilize the vast amount of product information available from heterogeneous sources in order to improve business analytics, decision support, and processes. This becomes even more challenging if those sources are distributed across multiple organizations. Federations of semantic information services, combining service-orientation and semantic technologies, provide a promising solution for this problem. However, without proper measures to establish information security, companies will be reluctant to join an information federation, which could lead to serious adoption barriers. Following the design science paradigm, this paper presents general objectives and a process for designing a secure federation of semantic information services. Furthermore, new as well as established security measures are discussed. Here, our contributions include an access-control enforcement system for semantic information services and a process for modeling access-control policies across organizations. In addition, a comprehensive security architecture is presented. An implementation of the architecture in the context of an application scenario and several performance experiments demonstrate the practical viability of our approach.}, language = {en} } @phdthesis{Kunz2013, author = {Kunz, Oliver}, title = {Die Ringschlussmetathese-/elektrozyklische Ring{\"o}ffnungssequenz : Entwicklung und Anwendung in der Synthese von Z,E-Diencarbons{\"a}uren}, address = {Potsdam}, pages = {193 S.}, year = {2013}, language = {de} } @article{SchmidtKunz2013, author = {Schmidt, Bernd and Kunz, Oliver}, title = {Stereoselective synthesis of dienyl phosphonates via extended tethered ring-closing metathesis}, series = {Organic letters}, volume = {15}, journal = {Organic letters}, number = {17}, publisher = {American Chemical Society}, address = {Washington}, issn = {1523-7060}, doi = {10.1021/ol4020078}, pages = {4470 -- 4473}, year = {2013}, abstract = {Allylphosphonates of allylic alcohols were converted to conjugated dienyl phosphonates in a one-flask reaction, comprising a ring-closing metathesis (RCM), a base-induced ring-opening, and an alkylation. The ring-opening proceeds with very high diastereoselectivity, giving exclusively the (1Z,3E)-configured dienes. Single diastereomers and mixtures of diastereomers can be used as starting materials without noticeable effect on the diastereoselectivity of the sequence.}, language = {en} } @article{SchmidtKunz2013, author = {Schmidt, Bernd and Kunz, Oliver}, title = {Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C-2-symmetric building block: a strategy for the synthesis of decanolide natural products}, series = {Beilstein journal of organic chemistry}, volume = {9}, journal = {Beilstein journal of organic chemistry}, publisher = {Beilstein-Institut zur F{\"o}rderung der Chemischen Wissenschaften}, address = {Frankfurt, Main}, issn = {1860-5397}, doi = {10.3762/bjoc.9.289}, pages = {2544 -- 2555}, year = {2013}, abstract = {Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru-lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.}, language = {en} } @article{SchmidtKunz2012, author = {Schmidt, Bernd and Kunz, Oliver}, title = {alpha,beta-Unsaturated delta-Valerolactones through RCM-Isomerization Sequence}, series = {Synlett : accounts and rapid communications in synthetic organic chemistry}, journal = {Synlett : accounts and rapid communications in synthetic organic chemistry}, number = {6}, publisher = {Thieme}, address = {Stuttgart}, issn = {0936-5214}, doi = {10.1055/s-0031-1290488}, pages = {851 -- 854}, year = {2012}, abstract = {alpha,beta-Unsaturated d-lactones are accessible via a sequential ring-closing metathesis (RCM) double-bond migration reaction starting from butenoates of allyl alcohols. This approach proceeds efficiently with lower catalyst loadings and higher initial substrate concentrations compared to the alternative RCM of acrylates derived from homoallylic alcohols.}, language = {en} } @article{FabianKunzKonnegenetal.2012, author = {Fabian, Benjamin and Kunz, Steffen and Konnegen, Marcel and M{\"u}ller, Sebastian and G{\"u}nther, Oliver}, title = {Access control for semantic data federations in industrial product-lifecycle management}, series = {Computers in industry : an international, application oriented research journal}, volume = {63}, journal = {Computers in industry : an international, application oriented research journal}, number = {9}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0166-3615}, doi = {10.1016/j.compind.2012.08.015}, pages = {930 -- 940}, year = {2012}, abstract = {Information integration across company borders becomes increasingly important for the success of product lifecycle management in industry and complex supply chains. Semantic technologies are about to play a crucial role in this integrative process. However, cross-company data exchange requires mechanisms to enable fine-grained access control definition and enforcement, preventing unauthorized leakage of confidential data across company borders. Currently available semantic repositories are not sufficiently equipped to satisfy this important requirement. This paper presents an infrastructure for controlled sharing of semantic data between cooperating business partners. First, we motivate the need for access control in semantic data federations by a case study in the industrial service sector. Furthermore, we present an architecture for controlling access to semantic repositories that is based on our newly developed SemForce security service. Finally, we show the practical feasibility of this architecture by an implementation and several performance experiments.}, language = {en} } @article{SchmidtKunzPetersen2012, author = {Schmidt, Bernd and Kunz, Oliver and Petersen, Monib H.}, title = {Total syntheses of naturally occurring seimatopolide a and its enantiomer from chiral pool starting materials using a bidirectional strategy}, series = {The journal of organic chemistry}, volume = {77}, journal = {The journal of organic chemistry}, number = {23}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/jo302359h}, pages = {10897 -- 10906}, year = {2012}, abstract = {Enantioselective total syntheses of both enantiomers of the recently isolated decanolide natural product seimatopolide A are described. The C-2-symmetric building blocks (R,R)-hexa-1,5-diene-3,4-diol (derived from D-mannitol) and its enantiomer (derived from L-(+)-tartrate) serve as key starting materials, which are elaborated in a bidirectional way using a selective mono-cross-metathesis, regio- and stereoselective epoxidation, and regioselective reductive epoxide opening to furnish the first fragment. Both enantiomers of the second fragment, 3-hydroxypent-4-enoic acid, were conveniently obtained through a lipase-catalyzed kinetic resolution and merged with the first fragment via Shiina esterification. An E-selective ring-closing metathesis was used to access the 10-membered lactone. A comparison of the specific optical rotations of synthetic seimatopolides with those reported for the natural product suggests that the originally assigned (3R,6R,7R,9S)-configuration should be corrected to (3S,6S,7S,9R).}, language = {en} } @article{SchmidtKunz2012, author = {Schmidt, Bernd and Kunz, Oliver}, title = {One-Flask tethered ring closing Metathesis-Electrocyclic ring opening for the highly stereoselective synthesis of conjugated Z/E-Dienes}, series = {European journal of organic chemistry}, journal = {European journal of organic chemistry}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-193X}, doi = {10.1002/ejoc.201101497}, pages = {1008 -- 1018}, year = {2012}, abstract = {A one-flask reaction sequence comprising ring closing metathesis (RCM) of butenoates derived from allylic alcohols and a base-mediated ring opening gives 2Z,4E-configured dienoic acids in high yields and stereoselectivities. Application of the method to the synthesis of the natural product fusanolide A suggests that the originally published structure was erroneously assigned and should be revised.}, language = {en} } @article{SchmidtAudoerschKunz2016, author = {Schmidt, Bernd and Audoersch, Stephan and Kunz, Oliver}, title = {Stereoselective Synthesis of 2Z,4E-Configured Dienoates through Tethered Ring Closing Metathesis}, series = {Synthesis}, volume = {48}, journal = {Synthesis}, publisher = {Thieme}, address = {Stuttgart}, issn = {0039-7881}, doi = {10.1055/s-0035-1562536}, pages = {4509 -- 4518}, year = {2016}, language = {en} }