Catenanos, Rotaxanos y Máquinas Moleculares / Catenanes, Rotaxanes and Molecular Machines

Catenanes and rotaxanes are particularly attractive compounds, mostly in relation to the novel properties that these molecules may exhibit. The use of Cu(I) as template allows to entangle two organic fragments around the metal centre before incorporating them in the desired catenane backbone. Based on this principle, numerous multicomponent molecular assemblies have been made such as, in particular, two-dimensional interlocking arrays. In relation to catenanes and rotaxanes, a particularly promising area is that of synthetic molecular machines. Various molecular machines have been elaborated and studied which contain transition metals as key elements. The potential of such controlled dynamic molecular systems will be discussed.

Because it separates primarily by fluorine content, fluorous reverse phase silica gel can be used in a chromatographic mode to separate fluorous molecules from each other. This separation forms the basis of new mixture synthesis techniques in which members of a series of substrates are tagged with different fluorous tags, mixed, carried through a series of reactions, and then separated based on the tag prior to detagging. Recent fluorous mixture syntheses of stereoisomer libraries of murisolins, passifloricins, and dictyostatins and other natural products will be highlighted.

El impresionante poder de la metátesis / The Awesome Power of Metathesis

The advent of well defined and highly tolerant catalysts for olefin metathesis, introduced by the groups of Schrock and Grubbs in the early 1990's, has changed the way how organic chemistry is currently practiced. Our group has helped to scrutinize this methodology for now more than a decade, inter alia by the total synthesis of natural products of increasing complexity. This lecture will summarize some of our recent projects in this field, which highlight the awesome power of olefin metathesis and reveal some of the few remaining limitations. In the second part of my seminar our work on alkyne metathesis will be surveyed, which constitutes a complementary way to harness the inherent advantages of metathetic transformations. The current status of this methodology will again be illustrated by selected applications to natural product chemistry

Nuevas aproximaciones a la síntesis de péptidos complejos / New Approaches for the Synthesis of Complex Peptides

Recent years have witnessed a revival in the field of peptides. Success in the field of peptide research is partly attributable to the fact that it is now possible to synthesize almost any peptide on both small and large scales. In this communication, several topics will be discussed. First of all, we will present a short overview of the use of peptides in medicine. Next, the most used synthetic strategies, which involve solid-phase, a combination of solid-phase solution, and chemical ligation, will be discussed for the synthesis of complex peptides from marine origin.

Reacciones dominó y múltiples catalizadas por Pd para la síntesis eficiente de productos naturales y materiales / Domino and Multiple Pd-Catalyzed Reactions for the Efficient Synthesis of Natural Products and Materials

Domino Reactions allow the synthesis of complex molecules in a highly efficient way starting from simple substrates. They are of special interest for the preparation of natural products and analogues which are important as lead structures for the development of bioactive compounds. Moreover, they can also be used for the synthesis of any type of material and in combinatorial chemistry. The quality of a domino reaction can be correlated to the increase of complexity in the process. In the lecture the synthesis of alkaloids, natural chromans, steroids, tetracylines and molecular switches will be described.

Jacqueline K. Barton , California Institute of Technology, Chemistry, CA, USA

Many experiments have now shown that double helical DNA can serve as a conduit for efficient charge transport reactions over long distances in vitro. This chemistry is exquisitely sensitive to perturbations in the DNA base stack and can be harnassed for sensitive diagnostics. Studies will be described to characterize biological roles for DNA charge transport. This chemistry may be used advantageously within the cell in long range signaling to DNA-bound proteins, both to regulate transcription and to activate repair of base lesions under conditions of oxidative stress. DNA charge transport chemistry provides an opportunity to carry out redox chemistry at a distance.

M. Christina White,Department of Chemistry, University of Illinois, IL, USA

Although it has been well demonstrated that given ample time and resources, highly complex molecules can be synthesized in the laboratory, too often current methods do not allow chemists to match the efficiency achieved in Nature. The discovery and development of highly selective C-H oxidation methods, similar to those found in Nature, for the direct installation of oxygen and nitrogen functionalities into allylic and aliphatic C-H bonds of complex molecules and their intermediates will be presented. Unlike Nature which uses elaborate enzyme active sites, we rely on the subtle electronic and steric interactions between C-H bonds and small molecule transition metal complexes to achieve high selectivities. Our current understanding of these interactions gained through preliminary mechanistic studies will be discussed. Novel strategies for streamlining the process of complex molecule synthesis enabled by these methods will be presented.

Larry E. Overman, Department of Chemistry, University of California, Irvine, CA, USA

The structural diversity of alkaloids is unparalleled among natural products. For many years, unique alkaloid structures have stimulated the development in our laboratories of new chemical transformations and new synthesis strategies. This lecture will discuss our recent progress in developing concise synthesis strategies for preparing several alkaloids having novel structures.

Reacciones de acoplamiento catalizadas por Paladio y Níquel / Palladium- and Nickel-Catalyzed Coupling Reactionss

Despite the tremendous accomplishments that have been described in the development of palladium- and nickel-catalyzed carbon-carbon bond-forming processes, it is nevertheless true that many significant opportunities remain. For example, to date the overwhelming majority of studies have focused on couplings between two sp2-hybridized reaction sites (e.g., an aryl metal with an aryl halide). As of 2001, there were few examples of palladium- or nickel-catalyzed coupling reactions of alkyl electrophiles. During the past several years, we have pursued the discovery of palladium- and nickel-based catalysts for coupling activated and unactivated primary and secondary alkyl electrophiles that bear b hydrogens. Our recent efforts to develop broadly applicable methods, including enantioselective processes, will be discussed.

M. Carmen Carreño, Dpto. Química Orgánica (C-I). Universidad Autónoma de Madrid, Madrid, Spain

Nuevas aplicaciones de quinonas y quinoles en síntesis asimétrica / New Applications of Quinones and Quinols in Asymmetric Synthesis

The efficacy of sulfoxides in diastereoselective auxiliary-induced reactions is nowadays well established. Their easy elimination and possible transformation into other functions increase their synthetic usefulness. This lecture will describe how we are using enantiopure sulfinyl quinone and p-quinol derivatives to synthesize bioactive molecules and polycyclic structures with helical chirality. Diels-Alder reactions and conjugate additions are essential tools en route to our targets. Proper choice of the partners allow domino reactions to occur, opening a rapid access to structurally complex molecules in a highly stereocontrolled manner.

Steve G. Davies, Chemistry Research Laboratory, Department of Chemistry, Oxford University, UK

Transformaciones estereoselectivas de Alilaminas / Stereoselective Transformations of Allylamines

The amino diol motif is a recurring structural component in a diverse range of biologically active natural products and synthesis molecules. The asymmetric synthesis of a range of natural products and other highly functionalized molecular architectures containing the amino diol unit, including sphingosine, jaspine B, and polyhydroxylated pyrrolidines utilizing a variety of synthetic methodology including asymmetric conjugate addition of nitrogen nucleophiles, novel cyclisation strategies and ammonium-directed dihydoxylation will be described.

Moderador / Chairperson: Julio Álvarez Builla, Dpto. Química Orgánica, Facultad de Farmacia, UAH, Spain

ENGLISH <> SPANISH : TRADUCCIÓN SIMULTANEA <> SIMULTANEOUS TRANSLATION PROVIDED

Conferencias : 40 minutos de conferencia y 10 m inutos de discusión al finalizar cada sesión / 40-minute talk; 10-minute discussion after each session.