Stereoselective Hydrocoupling of Cinnamic Acid Esters by Electroreduction: Application to Asymmetric Synthesis of Hydrodimers
作者:Naoki Kise、Shumei Iitaka、Keisuke Iwasaki、Nasuo Ueda
DOI:10.1021/jo026183k
日期:2002.11.1
The electroreduction of Ar-substituted methyl cinnamates in acetonitrile gave all-trans cyclized hydrodimers stereoselectively (58 approximately 90% de). In all cases, small amounts (<10% yield) of meso hydrodimers were also formed. The electrolysis was performed conveniently using an undivided cell at a constant current. The transition states for the hydrocoupling were calculated with semiempirical
Ar-取代的肉桂酸甲酯在乙腈中的电还原立体选择性地产生了全反式环化的二聚体(58约为90%de)。在所有情况下,也会形成少量(<10%的收率)内消旋二聚体。电解是使用恒定电压的不分隔电池方便地进行的。用半经验方法计算了水耦合的过渡态。全反式环化的二聚体被转化为C(2)对称的dl-3,4-二芳基己二酸和反式3,4-二芳基环戊烷。由(1R)-(+)-樟脑制备的手性辅助[(1R)-exo] -3-exo-(二苯甲基)冰片,对于通过电还原将肉桂酸酯进行立体选择性加氢偶联非常有效。(3R,4R)-3,4-二芳基己二酸酯和(3R,4R)-3,4-二芳基己烷-1