| Co-Investigator(Kenkyū-buntansha) |
OSAWA Shuichi Tohoku University, Inst.for Chem.Reac.Sci., Research Associate, 反応化学研究所, 助手 (00291055)
WATANABE Masataka Tohoku University, Inst.for Chem.Reac.Sci., Research Associate, 反応化学研究所, 助手 (10006330)
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| Research Abstract |
1. The absolute conformation of the retinal chromophore in rhodopsin is a central problem for understanding the visual transduction process. The absolute twist around the 12-13 single bond of the chromophore in rhodopsin has been reported on studies with 11-cis-locked chiral retinal analogues (1) with 3/7 membered ring system by Prof. Nakanishi et al. Columbia University. However, the absolute configuration of 1 disagrees with that obtained by the CD calculation. To determine the absolute stereochemistry of 1 in an unambiguous manner, we have applied "the chiral phthalic acid method" to 3/7 membered alcohol. Bicyclo [5.1.0] octan-2,6-diol (syn-2) was condensed with chiral dichlorophthalic acid (-)-3 to yield a diastereomeric mixture of esters (4), which was easily separated by HPLC on silica gel. p-Bromobenzoate (+)-(5) prepared from ester 4B crystallized as single crystals suitable for X-ray diffraction. The (1S, 2R, 7R) configuration of (+)-(5) was unambiguously determined by the X-r
… More
ay Bijvoet method.
2. As the fundamental information of bioactive compounds and chiroptically active organic materials recently developed, we are constructing the chirality database, "Chiral World." To collect many CD data, we have invited Prof. Kuball, University of Keiserslautern, and also sent Prof. Harada there, and we have developed the CD database format to normalize these data.
3. As the joint work with Prof. Pirkle, University of Illinois, various o-substituted diaryl methanols were enantioresolved by the chiral phthalic acid method as follows ; (1) esterification of racemic alcohols with chiral phthalic acid, (2) separation of a diastereomeric mixture of the esters formed by HPLC on silica gel, and (3) recovery of enantiopure alcohols from the separated esters. The absolute configurations of chiral phthalic acid esters of o-substituted diaryl methanols were unambiguously determined by the X-ray crystallography using the campharsultam moiety as the internal standard of absolute configuration. Less
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