手性氨基二醇的合成及其在二乙基锌对醛不对称加成反应中的应用

手性配体催化的烷基锌试剂对醛的不对称加成反应是合成光学活性二级醇的重要方法 1] ,1 0多年来 ,人们对其进行了深入的研究 ,并取得了很大进展 .其中大部分工作是设计如β-氨基醇等新的手性配体 .此外 ,文献 2～ 6]还报道了氨基二醇在这类反应中具有手性诱导效果 .为进一步研究手性配体催化的二乙基锌对醛的不对称加成反应 ,我们合成了新的手性氨基二醇配体 ,并将其用于该反应中 .1　结果与讨论1 .1　手性配体的合成　以 L -脯氨酸甲酯盐酸盐 ( 5 )为原料 ,与溴代乙酸乙酯反应生成 ( L ) - N - ( 2 -乙酰乙氧基 )脯氨酸甲酯 ( 6)反应 ,…

Preparation of Chiral Aminodiols and Their Applications in the Catalytic Enantioselective Addition of Diethylzinc to Aldehydes

Four new chiral aminodiols 1-4, which were prepared from methyl L proline in 2 steps, were applied in the enantioselective addition of diethylzinc to benzaldehyde. The results indicated that the enantioselectivities enhance with increasing the bulkiness of substituents on chiral ligands and with chiral ligand 4 giving the best result. When ligand 4 was used to catalyze the enantioselective addition of diethylzinc to aromatic aldehydes, the substituents affect the enantioselectivities slightly and 1 naphthaldehyde gives the best enantiomeric excess(up to 75.3% ). On the other hand, 4 (dimethylamino)benzaldehyde gives a low enantiomeric excess, which may most likely arise from a non steroselective ethyl transfer to aldehyde promoted by zinc coordination of amino group. For aliphatic aldehydes, poor enantiomeric excesses are generally given.