| Budget Amount *help |
¥4,190,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
Optically active organic germanium compounds bearing asymmetric germanium atom (methyl-1-naphtylphenylgermane and its derivatives) was previously reported by Brook et.al. However, far less attention has been devoted to optically active germyllithium or stannyllithium species. We report herein the results of a study of novel optically active germyllithium, using (-)-sparteine as a chiral ligand.
In the Schlenk tube, tert-butylmethylphenylgermyllithium (t-BuMePhGeLi) (1) was prepared by the reaction of the corresponding hydrogermane with tert-butyllithium in THF in the presence of half amounts of (-)-sparteine. The compound of 1 was characterized by ^1H, ^7Li and ^13C NMR spectra. The ligand-exchange reaction between 1-(sp) and 1-(THF)_2 was observed by variable-temperature NMR spectroscopy. The coalescence point was 107℃, and free energy of activation was calculated to be 18.0 kcal/mol. Optical resolution of germyllithium with (-)sparteine (1^*) was succeeded by recrystallization from n-
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hexane / toluene mixed solvent. The molecular structure of 1^* was determined by X-ray diffraction. As a result, absolute configuration of optically active 1^* was R configuration.
This method could also be applied to synthesis of optically active stannyllithium. Optical resolution of stannyllithium was succeeded by only addtion of half amount of (-)-sparteine into the racemic mixture of tert-butylmethylphenylstannyllithium (t-BuMePhSnLi) (2). The optically pure stannyllithium (-)-sparteine complex 2-(sp) was obtained as colorless crystals and its absolute structure had R configuration determined by X-ray crystallography.
In the presence of (-)-sparteine, tert-butylmethylgermane (t-BuMeGeH_2) was reacted with sec-butyllithium to give a (-)-sparteine complex of tert-butylmethylhydrogermyllithium (t-BuMeHGeLi, 3), quantitatively. 3-(sp) was added to triphenylchlorosilane to yield a coupling product of tert-butylmethyl (triphenylsilyll germane (t-BuMeHGeSiPh_3). The resulting optically active silylgermane shows 48%ee, and the absolute structure of the main product was determined by a single crystal X-ray diffraction to be S configuration. Less
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