Synthesis of (<i>Z</i>)-Alkene and (<i>E</i>)-Fluoroalkene-Containing Diketopiperazine Mimetics Utilizing Organocopper-Mediated Reduction−Alkylation and Diastereoselectivity Examination Using DFT Calculations
作者:Ayumu Niida、Makiko Mizumoto、Tetsuo Narumi、Eriko Inokuchi、Shinya Oishi、Hiroaki Ohno、Akira Otaka、Kazuo Kitaura、Nobutaka Fujii
DOI:10.1021/jo060202z
日期:2006.5.1
by trapping the resulting metal dienolate with an electrophile in a one-pot procedure gave α-alkylated-β,γ-unsaturated-δ-lactams in good yields. Because of side-chain steric repulsion, we found that alkylation using relatively large electrophiles such as BnBr gave mostly 3,6-trans isomers by kinetic trapping of metal enolates. On the other hand, MeI-mediated alkylations predominantly provided the unexpected
我们仔细检查了有机铜介导的γ-乙酰氧基或γ,γ-二氟-α,β-不饱和-δ-内酰胺的还原烷基化反应,以合成含(Z)-烯烃-或(E)-氟烯烃的二酮哌嗪模仿物。乙酸盐的还原2,12,14,和difluorolactam 18与高阶铜酸盐试剂(ME 3 CuLi 2·LiI·3LiBr),然后在一锅法中用亲电子试剂捕获所得的金属二烯酸酯,以良好的产率得到α-烷基化的β,γ-不饱和的δ-内酰胺。由于侧链空间排斥,我们发现使用相对较大的亲电子试剂(如BnBr)进行烷基化可通过动态捕获金属烯醇化物产生3,6-反式异构体。另一方面,尽管存在庞大的苄基侧链,但MeI介导的烷基化仍主要提供了意想不到的3,6-顺式异构体。基于密度泛函理论计算,我们得出结论,3,6-顺式异构体的形成是由于oxa-π-烯丙基锂络合物29和31的出现。