The carbonyl group at the 2-position of levoglucosenone is reduced to obtain a hydroxyl group having a .beta.-configuration. The hydroxyl group having a .beta.-configuration is reversed to an .alpha.-configuration, and hydroxyl groups are added at the 3- and 4-positions in a cis-.alpha. form. Finally, the protective group of the hydroxyl group at the 2-position is eliminated. The reduction of the carbonyl group at the 2-position can be performed such that the levoglucosenone is reacted with aluminum lithium hydride or sodium boron hydride in an appropriate solvent. Reversion of the hydroxyl group having a .beta.-configuration can be performed by the Mitsunobu method or a method having a mesylation step and a step using cesium acetate. The addition of the hydroxyl groups to the 3-and 4-positions in the cis form can be performed by oxidizing the double bond across the 3- and 4-positions with an appropriate oxidizing agent. The elimination of the protective group of the hydroxyl group at the 2-position can be performed under basic conditions in accordance with normal methods. According to the method of the present invention, D-allosan can be obtained stereoselectively in high yield via a smaller number of steps than that of the conventional synthesis method.
在得到一个具有β-构型的羟基团之后,对
蔗糖醛酮的2位上的羰基团进行还原。将具有β-构型的羟基团转变为α-构型,然后以顺式α形式在3位和4位加入羟基团。最后,消除2位处羟基团的保护基团。对2位处羰基团的还原可以通过将
蔗糖醛酮与适当溶剂中的铝
锂氢化物或
硼氢化钠反应来完成。具有β-构型的羟基团的转变可以通过Mitsunobu方法或包含甲磺酰化步骤和使用
乙酸铯的方法来完成。以顺式形式在3位和4位加入羟基团可以通过适当的氧化剂氧化3位和4位之间的双键来完成。2位处羟基团的保护基团的消除可以根据常规方法在碱性条件下完成。根据本发明的方法,可以通过比传统合成方法更少的步骤高产率地立体选择性地获得D-阿洛三糖。