Development of CD Method and Applications to Stereochemistry

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The CD spectroscopic method, together with the X-ray crystallographic method, is useful for determination of the absolute stereostructure of chiral organic compounds. We have proposed, as an extension of the CD exciton chirality method, a new theoretical method for nonempirical determination of the absolute stereochemistry of twisted pi-electron systems. The CD spectra can be theoretically calculated by the pi-electron SCF-CI-DV molecular orbital method, and we have determined the absolute stereostructures of the following biologically active natural products and synthetic chiral organic compounds with theoretical interest.1.The electronic structure of rho-methoxycinnamate chromophore suitable for application of the CD exciton chirality method to oligosaccharides was clarified.2.absolute stereochemistry at C-12 in 12-hydroxylated neo-clerodane diterpenoids was determined by CD and X-ray methods.3.Chiral olefins with molecular asymmetry were synthesized, and their absolute stereostructu … More res were determined by the CD method. the kinetics and mechanism of their photo and thermal racemization were also clarified.4.CD and absolute stereochemistry of chiral bridged biphenyls were studied.5.We found that a chiral biscyanine dye exhibits unusually strong exciton split in UV-VIS absorption and CD spectra, and the origin and nature of its unique exciton coupling behavior were clarified.6.We developed a CD exciton method for determination of the absolute stereochemistry of acyclic 1,3-dibenzoate systems.d the origin and nature of its unique exciton coupling behavior were clarified.7.Chiral spiroaromatic compounds with 9,9'-spirobifluorene skeleton including[6,6]-vespirene were synthesized and their absolute stereostructures were determined by the CD method.8.We have succeeded in the first determination of the absolute stereochemistry of atropisomeric biflavone, (-)-4',4''',7,7''-tetra-O-methylcupressuflavone, by theoretical calculation of CD spectra.9.A chiral probe useful for optical resolution and X-ray crystallographic determination of the absolute stereochemistry of chiral carboxylic acids was developed.10.We revised, by X-ray crystallographic and CD spectral studies, the absolute stereochemistry of (8)-and(10)-paracyclophane carboxylic acids previously erroneously determined on the basis of chemical correlation. Less