Development of a novel synthetic route to optically active anthracyclinones: Preliminary synthesis of the racemic key intermediate.
作者:NORIHIKO TANNO、SHIRO TERASHIMA
DOI:10.1248/cpb.31.811
日期:——
In order to develop a novel synthetic route to a key synthetic intermediate ((R)-(-)-3) for optically active anthracyclinones (2a-d), preparation of the racemic intermediate ((±)-3) from the α, β-unsaturated ketone (6), obtainable from the α, β-unsaturated acid (5) or the 2-tetralone (11), was attempted according to the designed synthetic scheme. Since epoxidation of the racemic allylic alcohol ((±)-7) produced by reduction of 6, followed by reductive cleavage of the epoxides ((±)-8a, b) and oxidation of the vicinal-diol ((±)-9a), was found to readily give the desired (±)-3 in good overall yield, optically pure (R)-(-)-3 should be obtainable from 6 if 6 can be asymmetrically reduced to afford (S)-7 in a high optical yield. The racemic ketone ((±)-3) was further transformed to (±)-7-deoxy-4-demethoxy-daunomycinone dimethyl ether ((±)-13), from which racemic 4-demethoxyanthracyclinone ((±)-2c, d) could be elaborated.
为了开发出一条通向光学活性蒽环类化合物(2a-d)的关键合成中间体((R)-(-)-3)的新合成路线,我们根据设计的合成方案,尝试从α,β-不饱和酮(6)制备外消旋中间体((±)-3),该中间体可从α,β-不饱和酸(5)或 2-四氢萘酮(11)中获得。由于发现通过还原 6 生成的外消旋烯丙基醇((±)-7)的环氧化反应,随后环氧化物((±)-8a, b)的还原裂解和沧醛二醇((±)-9a)的氧化反应很容易得到所需的(±)-3,而且总收率很高,因此如果 6 可以不对称地还原,以高光学收率得到(S)-7,那么就可以从 6 得到光学纯度为(R)-(-)-3。外消旋酮((±)-3)进一步转化为(±)-7-脱氧-4-去甲氧基-金霉素酮二甲醚((±)-13),并由此制备外消旋 4-去甲氧基蒽环酮((±)-2c, d)。