| 摘要 |
PURPOSE:To obtain the derivative useful as an intermediate for optically active steroid compounds, esp. vitamin D derivatives, by asymmetric reduction of a specific phosphonoester derivative as a readily available raw material, in the presence of a basic compound. CONSTITUTION:The derivative of formula I [R<1> is an optically active alcohol residue; * means that the absolute configuration of the asymmetric carbon atom in question stands at (R) or (S)] is obtained by asymmetric reduction of a phosphonoester derivative of formula II [R<2> is a (substituted) lower alkyl] in the presence of a basic compound. It is recommended that, for example, the basic compound be n-butyllithium and the reaction conducted in a solvent such as tetrahydrofuran at -80 to 20 deg.C. |
