Stereoselective synthesis of highly enantioenriched 3-methyl-2-cyclohexen-1-ones possessing an asymmetric quaternary carbon as C-4 or C-6: a sugar template approach
作者:Hiroto Kubo、Ikuko Kozawa、Ken-ichi Takao、Kin-ichi Tadano
DOI:10.1016/j.tetlet.2007.12.031
日期:2008.2
a 3-methyl-2-cyclohexen-1-one-4- (or -6-) carboxylic acid as the O-4 ester, in which C-4 or C-6 is an asymmetric quaternary carbon. Removal of the sugar template from those aldol condensation products provided synthetically useful 3,6-dimethyl-2-cyclohexen-1-one-6-carboxylic acid and 3,4-dimethyl-2-cyclohexen-1-one-4-carboxylic acid derivatives both in high enantioenriched forms.
由6-脱氧-2,3-二-O-(叔丁基二甲基甲硅烷基)-α-d-吡喃葡萄糖苷的C-4处的C-4掺入的α-甲基化乙酰乙酸酯生成的烯醇盐的1,4-加成,然后在两个碱介导的条件下将所得的1,4-加成产物进行羟醛缩合,提供具有高非对映选择性的4-O-官能化d-葡萄糖衍生物。这些产品将3-甲基-2-环己烯-1-酮-4-(或-6-)羧酸安装为O-4酯,其中C-4或C-6是不对称季碳原子。从那些醛醇缩合产物中除去糖模板提供了合成上有用的3,6-二甲基-2-环己烯-1-一-6-羧酸和3,4-二甲基-2-环己烯-1-一-4-羧酸都以高对映体富集的形式存在。