A new class of oxazolidinone chiral auxiliary has been synthesized from various α-amino acids, incorporating a perfluoroalkyl functional chain as a soluble support. This feature allows the chiral auxiliaries to be employed under standard solution-phase reaction conditions, and rapidly purified from crude mixtures using fluorous solid phase extraction (FSPE). Our investigation of these new materials has been divided into two main sections. To obtain the chiral auxiliaries in multi-gram quantities a synthetic protocol was designed, where efficiency and reproducibility were the primary objectives. Meeting these goals required an extensive study of the reactivity of perfluoroalkyl nucleophiles. This study identified a versatile and scalable protocol for the perfluoroalkylation of the required amino acid starting materials. These results have allowed us to design a general, five-step synthetic pathway to create the fluorous chiral auxiliaries quickly and effectively. The new auxiliaries were then applied in several model reactions, specifically chosen to examine the reactivity and behavior of these compounds. In particular, the auxiliaries were tested for their stereoselectivity, recyclability, and ease of purification, in a series of Aldol reactions, 1,3 dipolar cycloadditions, and radical conjugate additions. This set of model reactions, combined with the facile and efficient synthesis clearly demonstrates that these new chiral auxiliaries are useful alternatives to the non-fluorous oxazolidinone chiral auxiliaries currently employed in stoichiometric asymmetric syntheses. / February 2006

La generación de nuevas estructuras convertidoras y su modelado matemático son las dos temáticas principales estudiadas en esta tesis. El seguimiento de una metodología que modifica la estructura del circuito, realizando una ruptura de la simetría con base en los resultados de simulación, permitió generar la familia de convertidores en "interleaving" asimétrico compuesta por el AIDB, el AIDBB y el grupo-AIDF. En el apartado de modelado se ha desarrollado una nueva aproximación conceptual inspirada en las ideas de trabajos previos que se estudian en el estado del arte. El nombre dado a esta nueva aproximación es: Promediado Modificado Usando Métodos Gráficos. Este nuevo enfoque ha sido utilizado para obtener el modelo promediado de la nueva familia de convertidores en el espacio de estados. Las mediciones experimentales de la respuesta en frecuencia del convertidor AIDB y el diseño del controlador LQR permitieron verificar la aproximación del modelo en pequeña señal obtenido. / The two main topics presented in this thesis are the generation and mathematical modelling of new converter structures. The fundamental idea behind the methodology used to generate the new converter structures was to break the symmetry. This involved modifying the circuit structure on the basis of the simulation results. This methodology allowed the generation of the family of asymmetrical interleaved converters, which consists of the AIDB, the AIDBB and the AIDFgroup. A new conceptual modelling approach was developed on the basis of ideas taken from previous research which is reviewed in the state of the art. This approach was called Modified Averaging Using Graphical Methods. Because of its features, this new method can be used to model the state space average of the new converter family presented here. The accuracy of the AIDB converter small signal model was verified by measuring the frequency response and by designing an LQR controller.

This thesis is a survey on the approximability of the asymmetric traveling salesmanproblem with triangle inequality (ATSP).In the ATSP we are given a set of cities and a function that gives the cost of travelingbetween any pair of cities. The cost function must satisfy the triangle inequality, i.e.the cost of traveling from city A to city B cannot be larger than the cost of travelingfrom A to some other city C and then to B. However, we allow the cost function tobe asymmetric, i.e. the cost of traveling from city A to city B may not equal the costof traveling from B to A. The problem is then to find the cheapest tour that visit eachcity exactly once. This problem is NP-hard, and thus we are mainly interested in approximationalgorithms. We study the repeated cycle cover heuristic by Frieze et al. We alsostudy the Held-Karp heuristic, including the recent result by Asadpour et al. that givesa new upper bound on the integrality gap. Finally we present the result ofPapadimitriou and Vempala which shows that it is NP-hard to approximate the ATSP with a ratio better than 117/116.

(-)-Gymnodimine is a member of a growing family of spirocylic imine containing marine natural products. The construction of the complete skeleton of (-)- gymnodimine has been accomplished in a convergent manner in 23 steps (the longest linear sequence). A highly diastereo- and enantioselective Diels-Alder reaction employing bis(oxazoline)·Cu(II) catalyst provided the spirolactam core structure of gymnodimine bearing a quaternary carbon stereogenic center. An improved procedure for hydrostannylation of the hindered internal triple bond in 96a was discovered by slow addition of tributyltin hydride to minimize formation of hydrogenated byproduct. Fragment coupling featured a Nozaki-Hiyama-Kishi reaction between a vinyl iodide derived from the spirolactam and a tetrahydrofuran moiety. The macrocyclization was realized through a rather unusual intramolecular opening of an activated Ntosyllactam by an alkyllithium species generated in situ. The butenolide was appended through a vinylogous Mukaiyama aldol addition of silyloxyfuran 155 to the ketone 163 under meticulously controlled conditions. The generality of this process was explored in some detail. Addition of silyloxyfurans to cyclohexanones proceeds with moderate to good diastereoselectivities. The potential application of this process to the synthesis of butenolide and g-lactone containing natural products was demonstrated by further transformations of the addition adducts. Finally, toward our goal of developing an enzyme-linked immunosorbent assay (ELISA) for gymnodimine monitoring a hapten derived from the tetrahydrofuran has been synthesized. Even though the raised antibodies failed to recognize the natural product itself, the results provided some information regarding the essential structural elements of an efficient hapten.

The goal of the thesis is to fabricate the integrated asymmetric Mach-Zehnder Interferometer and Optical waveguide Ring Resonator with simple fabrication process. A 1.49

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This paper examines the properties of the perfect Bayesian Nash equilibrium or equilibria in a model where the new car market coexists with the lemon market which has adverse selection problems. Under such a setting, it is shown that the price of a new car will be affected indirectly by the problems of adverse selection in the lemon market.

Our purpose is to examine: what should be the best subsidy mechanism which can reduce the lost from the asymmetric information problem whereas the administration performs a subsidy policy. We use the incentive contract theory to establish our models, and analyze different kinds of subsidy policy results. We prove that: compare with the partial equally subsidy, zero-subsidy and full-purchase subsidy, the partial discriminably subsidy is the best subsidy policy.

A new scheme of asymmetric elliptic-cone-shaped microlens (AECSM) employing a single-step fabrication technique for efficient coupling between the high-power 980nm laser diodes and the single-mode fibers is proposed. The asymmetric elliptic-cone-shaped fiber endface (AECSFE) was fabricated by a single-step grinding and polishing a cleaved fiber by applying a periodically variable torque on the fiber ferrule to change the grinding pressure. The periodically variable torque was made by an eccentric mass with a constant rotation speed double that of the fiber. After the AECSFE was formed, an AECSM was obtained by heating the fiber tip in a fusing splicer. In comparison with the previous works on asymmetric fiber microlenses fabricated by the multi-step processes with complicated fabrication, the advantages of the AECSM structure for achieving high coupling are a single-step fabrication, a reproducible process, and a high-yield output. In this study, we demonstrated that the average grinding offset of the AECSM structure for 30 measurements was about 0.4 £gm, the average coupling efficiency was 71%, and the maximum of the measured coupling efficiency was 83%. The yield of the AECSM for coupling efficiency over 70% was 47%, for coupling efficiency over 60% was almost 100%.

名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成8年7月12日 服部洋兒氏の博士論文として提出された