Browsing by Subject "Symmetry (Physics)"
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Item Applications of chiral N-sulfinylcarbamates in asymmetric synthetic methodologies(1988) Carpenter, Joel Francis, 1961-; Whitesell, James K.Using (R)-8-phenylmenthol and trans-2-phenyl-cyclohexanol as chiral auxiliaries, the stereoselectivities of the [4+2] cycloaddition and the ene reactions of their respective N-sulfinylcarbamates are explored. In the presence of a Lewis acid, the cycloadditions exhibit inductions greater than 95:5 with the former of these two sources of chirality, affording dihydrothiazine 1-oxides which have been extensively elaborated to chemically useful and important synthons. The ene reactions with a Lewis acid present are also highly stereoselective, yielding the N-(alkoxycarbonyl)-allylicsulfinamides of which a useful transformation is developed and reported here. The net effect of this transformation is a regio- and and stereoselective allylic oxidation of an unactivated alkene with complete reagent control of the absolute stereochemistry. The significance of this chemistry is clearly illustrated by the synthesis of an intermediate towards PGF₂[subscript alpha] where a remote stereocenter is enantioselectively introducedItem The Neʼeman-Fairlie SU(2/1) model: from superconnection to noncommutative geometry(2004) Asakawa, Takeshi; Fischler, WillyThe gauge symmetries provide the Standard Model, and it involves a Spontaneous Symmetry Breakdown (SSB), which is called the Higgs Mechanism. However, the geometrical formulation that can include the SSB and the unification of gauge groups have not solved yet. In order to solve these problems, we pay attention to two geometrical tools, that is, the superconnection and Noncommutative Geometry (NCG). And we consider the supergroup SU(2/1) as a candidate of the electroweak unification group. The SU(2/1) unification model was formulated with several geometrical frameworks, mainly, superconnection and the Mainz-Marseille (MM) version of NCG. On the other hand, the Connes-Lott (CL) model with an ‘original’ NCG was suggested without the supergroup SU(2/1). In these models the Higgs scalar field can be geometrically formulated. In this dissertation we attempt the new Ne’emanFairlie SU(2/1) model in the geometrical framework of the CL model. By assuming the 3 × 3 lepton and the 4 × 4 quark representations of SU(2/1) in the generalized on