Enantio- and diastereoselective aldol reactions of achiral ethyl and methyl ketones with aldehydes: the use of enol diisopinocampheylborinates
作者:Ian Paterson、Jonathan M. Goodman、M. Anne Lister、Russell C. Schumann、Cynthia K. McClure、Roger D. Norcross
DOI:10.1016/s0040-4020(01)85588-5
日期:1990.1
from achiral ethyl and methyl ketones by enolisation in the presence of tertiary amine bases (iPr2NEt or Et3N), undergo enantio- and diastereoselective aldol reactions with aldehydes. The reagents employed, (+)- and (-)-(Ipc)2BOTf, are easily prepared in enantiomerically pure form in two steps from (-)- and (+)-α-pinene, respectively. The aldol reaction between ethyl ketones and aldehydes using (+)- or
通过在叔胺碱(i Pr 2 NEt或Et 3 N)存在下进行烯醇化而衍生自非手性乙基和甲基酮的烯醇二异opinocampheylborinates与醛进行对映和非对映选择性醛醇缩合反应。(+)-和(-)-(Ipc)2 BOTf所用的试剂易于分别从(-)-和(+)-α-pine烯分两步以对映体纯形式制备。使用(+)-或(-)-(Ipc)2 BOTf / i Pr 2 NEt在二氯甲烷中的乙酮与醛之间的醛醇缩合反应,通过衍生的手性Z-烯醇硼酸酯得到syn对映体过量(66-93%ee)和非对映选择性高(> -95%)的-α-甲基-β-羟基酮。相反,二乙基酮经由异构的E-烯醇二异松香樟脑硼酸酯(通过用(-)-(Ipc)2 BCl烯醇化)与甲基丙烯醛的抗选择性醛醇缩合反应的对映选择性可忽略不计。在与醛甲基酮的醛醇缩合反应的三氟甲磺酸酯和氯化试剂二者的使用提供了在中等对映体过量在醛的选择性enanti