| 摘要 |
<p>PURPOSE:To economically obtain the subject partially new compound by regioselectively reducing a malic acid diester derivative with NaBH4 as a reducing agent in a solvent mainly containing an alcohol (or in the presence of an acid in an aprotic solvent). CONSTITUTION:A compound expressed by formula I (R1 and R2 are alkyl or aralkyl; R3 is H, alkyl, aralkyl or R4 which may have a substituent group; R4 is silyl type protecting group), especially an optically active L-or D-malic acid ester derivative is regioselectively reduced with relatively inexpensive NaBH4 in either of the following cases. (a) in the presence of preferably a base, especially triethylamine in an alcohol or a mixed solvent containing the alcohol as a principal component and an aprotic polar solvent and (b) in the presence of an acid, preferably an organic carboxylic acid, especially acetic acid in an aprotic solvent. Thereby, the objective partially new compound, expressed by formula II (formula III is new; R5 is respective groups in R2) and useful as an intermediate for medicines is effectively and economically obtained.</p> |
