Enders’ SAMP-Hydrazone as Traceless Auxiliary in the Asymmetric 1,4-Addition of Cuprates to Enones
作者:Karsten Sammet、Christoph Gastl、Angelika Baro、Sabine Laschat、Peter Fischer、Ina Fettig
DOI:10.1002/adsc.201000412
日期:2010.9.10
Conjugate additions of Gilman cyanocuprates to (S)‐N‐amino‐2‐(methoxymethyl)pyrrolidine (SAMP)‐hydrazones 4, 5 derived from cyclic and acyclic α,β‐unsaturated ketones were investigated. A protocol utilizing copper(II) sulfate/ammonium chloride was evolved, which allowed cleavage of SAMP (S)‐1 under the hydrolysis and work‐up conditions, followed by recovery of the auxiliary with ethylenediaminetetraacetic
吉尔曼cyanocuprates的共轭加成到(小号) - ñ -氨基-2-(甲氧基甲基)吡咯烷(SAMP)-hydrazones 4,5从环状和无环α衍生,β不饱和酮进行了研究。制定了使用硫酸铜(II)/氯化铵的方案,该方案允许在水解和后处理条件下裂解SAMP(S)-1,然后用乙二胺四乙酸(EDTA)回收助剂。对于环状SAMP-hydr 4而言,铜酸盐添加物的对映选择性主要受铜酸盐烷基取代基和环大小的影响,在无环亚芳基SAMP-hydr 5的情况下然而,由于芳基取代基的性质。给电子的取代基的对映体过量差,而吸电子基团的ee值极佳,为98–99%。确定新立体中心的配置为(R)。此外,反应序列被开发它集成了串联1,4-加成/甲基化和辅助(的无痕迹水解裂解小号) - 1在一个单釜反应中,所得的对映体纯的甲基酮11 - 13,它们中的每ee大于99%。