| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
(1R, 4R)-bis(1-phenylliydroxymethyl)ferrocene (FERRODIOL) has been shown to be an effective ligand for the scandium complex which catalyzes the asymmetric Diels-Alder reaction of cyclopentadiene with 3-acyloxazolidin-2-one in high enantioselectivity. The success of FERRODIOL as a chiral ligand in asymmetric synthesis prompt us to prepare the corresponding 1, 4-ferrocenyl diamine ligand. The treatment of (1R, 4R)-bis(phenylmethyl)-ferrocenyl diacetate with aqueous animonium in THF/MeOH at room temperature for 18 h to prepare 1, 4-ferrocenyl diamine. However, the product was obtained as a single diastereomer of the (1R, 4R, Sp)-acetamido alcohol with retention of configuration: the structure of the acetamide alcohol was confirmed by X-ray diffraction analysis. The substitution by ammonia took place at only the C(6) carbon showing that the aminolysis occurred regioselectively at the one side of the two acetates. Similarly, hydrolysis of (1R, 4R)-bis(phenyhnethyl)ferrocenyl diacetate at room temperature for 18 h occurred regio-and stereoselectively to give the optically active half ester in a.good yield. The ease of the substitution may depend on the geometry of the two stereogenic centers. In only one of the acetoxy group suitably aligned for ionization (exo to the ferrocenyl group) to proceed efficiently; the aminolysis took place smoothly by the iron-assisted ionization, i.e., neighboring group participation. The leaving group on the second acetoxy group is not suitably aligned (endo to the ferrocenyl group) and also cannot undergo a conformational change for it to adopt the appropriate orientation for ionization to occur.In conclusion, this reaction is the first case of an aminolysis and hydrolysis in a chiral molecule that a conformational difference between two leaving groups happened to affect a rate of aminolysis and hydrolysis at two stereogenic centers.
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