The total synthesis of (-)-cyanthiwigin F by means of double catalytic enantioselective alkylation

Double catalytic enantioselective transformations are powerful synthetic methods that can facilitate the construction of stereochemically complex molecules in a single operation. In addition to generating two or more stereocentres in a single reaction, multiple asymmetric reactions also impart increased enantiomeric excess to the final product in comparison with the analogous single transformation. Furthermore, multiple asymmetric operations have the potential to independently construct several stereocentres at remote points within the same molecular scaffold, rather than relying on pre-existing chiral centres that are proximal to the reactive site. Despite the inherent benefits of multiple catalytic enantioselective reactions, their application to natural product total synthesis remains largely underutilized. Here we report the use of a double stereoablative enantioselective alkylation reaction in a concise synthesis of the marine diterpenoid (-)-cyanthiwigin F (ref. 8). By employing a technique for independent, selective formation of two stereocentres in a single stereoconvergent operation, we demonstrate that a complicated mixture of racemic and meso diastereomers may be smoothly converted to a synthetically useful intermediate with exceptional enantiomeric excess. The stereochemical information generated by means of this catalytic transformation facilitates the easy and rapid completion of the total synthesis of this marine natural product

Material flow based eco-balancing and evaluation of a beer production process - case study

SIGLEAvailable from TIB Hannover: RR 4485(2000,7) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Stoffstrombasierte Oekobilanzierung und Bewertung eines Bierherstellungsprozesses. Fallstudie

SIGLEAvailable from TIB Hannover: RR 4485(2000,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Multidimensional Analysis of Process Chains Regarding the Resource-efficient Manufacturing of Hybrid Structures

AbstractOne of the leading topics in the automotive industry as well as in the aircraft and aerospace sector is the use of lightweight structures for weight reduction. For this purpose, hybrid materials, e.g. metal-plastic structures, are of essential importance. Despite the high technological challenge, the manufacturing techniques still provide versatile development potential. Especially the integration of separate production techniques in one single tool opens new possibilities of successfully designing a resource-efficient process chain for hybrid components, suitable for series production.Within the Cluster of Excellence “MERGE Technologies for Multifunctional Lightweight Structures”, a modelling approach for the resource-efficient process design of the manufacturing of hybrid structures, which is based on a multidimensional analysis, will be developed. Besides the technical optimisation, the energy efficiency, the cost-effectiveness, the robustness of process chains as well as the maturity regarding series production will be considered during the entire development process. The paper will present main features of this modelling approach including a proposal for a systematic and structured procedure of a multidimensional analysis