| 摘要 |
PURPOSE:To readily and stereoselectively obtain the subject compound in high yield by asymmetrically hydrogenating a 4-tert-butoxyacetoacetic acid ester in the presence of a specific catalyst, then carrying out carbon chain extending reaction and further asymmetrically hydrogenating the resultant optically active ester using a specified catalyst. CONSTITUTION:A 4-tert-butoxyacetoacetic acid ester which is expressed by formula I (R<1> is lower alkyl; t-Bu is tert-butyl) and can be synthesized from a 4- chloroacetoacetic acid ester is asymmetrically hydrogenated in the presence of a ruthenium-optically active phosphine complex expressed by formula II [formula III is formula IV (R<2> is H or CH3); R<3> is R<1> or CF3] as a catalyst to form an optically active ester expressed by formula V, which is then reacted with a lithium enolate of an acetic acid ester to afford an optically active ester expressed by formula VI (R<4> is R<1>). The resultant optically active ester expressed by formula VI is then subjected to asymmetric hydrogenating reaction in the presence of a ruthenium-optically active phosphine complex expressed by formula VII (Et is ethyl) as a catalyst to provide the objective compound, expressed by formula VIII and useful as an intermediate for raw materials employed in synthesizing medicines, such as cholesterol synthetase inhibitor. |
