a Cu(II) salt and TBAT yielding the corresponding copper dienolate is addressed. A combined NMR and cyclic voltammetry analysis first highlight the role of TBAT in the Cu(II) to Cu(I) reduction and the structure of the precatalytic species. From these first results a second set of NMR and theoretical studies enable the determination of the structure and the mechanism of formation of the copper dienolate
讨论了甲硅烷基二烯酸酯,Cu(II)盐和TBAT的反应产生相应的二烯丙基铜的反应。NMR和循环伏安分析相结合,首先突出了TBAT在Cu(II)还原为Cu(I)和预催化物质结构中的作用。从这些第一结果中,第二组NMR和理论研究使得能够确定二烯酸铜铜催化物质的结构和形成机理。最后,我们表明,铜催化剂通过二烯醇铜中间体促进了甲硅烷基二烯醇盐前体的E / Z s-顺式/ s-反式平衡。所有这些结果揭示了催化的和不对称的乙烯基Mukaiyama反应的某些特性。
Stereospecific Hydrogenolysis of Lactones: Application to the Total Syntheses of (<i>R</i>)-<i>ar</i>-Himachalene and (<i>R</i>)-Curcumene
作者:Kim Spielmann、Renata Marcia de Figueiredo、Jean-Marc Campagne
DOI:10.1021/acs.joc.7b00419
日期:2017.5.5
A straightforward strategy for the syntheses of curcumene and ar-himachalene is reported. Synthetic highlights include a catalytic and asymmetric vinylogous Mukaiyama reaction and a stereospecific hydrogenolysis of a tertiary benzylic center using Pd/C or Ni/Raney catalysts. Notably, using Ni/Raney, the stereoselectivity outcome (inversion vs retention) of the hydrogenolysis depends on the tertiary