Enantioselective [4+2] cycloaddition reaction of α,β-unsaturated imine and methyl vinyl ketone catalyzed by chiral phosphine
作者:Ge Wang、Rukeya Rexiti、Feng Sha、Xin-Yan Wu
DOI:10.1016/j.tet.2015.04.076
日期:2015.6
New bifunctional phosphines were prepared as chiral organocatalysts for the enantioselective [4+2] cycloaddition between α,β-unsaturated imines and methylvinylketone. In the presence of 10 mol % of amide-phosphine, the [4+2] cycloaddition reaction was achieved in good-to-excellent yields (up to 95%) and diastereoselectivities (up to 99:1 dr) with moderate-to-good enantioselectivities (up to 82% ee)
unexpected and efficient dominoreaction of N-sulfonyl-1-aza-1,3-dienes with 2-halo-1,3-dicarbonyl compounds to synthesize differently substituted 2,3-dihydrofuran derivatives with excellent regio-, chemo-, and stereoselectivity in moderate to good yields was developed. In this transformation, broad substrate scope was demonstrated, and a plausible mechanism for this novel dominoreaction was given.
Switchable Access to Different Spirocyclopentane Oxindoles by N-Heterocyclic Carbene Catalyzed Reactions of Isatin-Derived Enals and N-Sulfonyl Ketimines
fused spirocyclopentane oxindoles with four contiguousstereocenters, including twoquaternary carbon centers, was developed. Alternatively, spirocyclopentane oxindoles containing an enaminone moiety can be achieved using the same starting materials, isatin‐derived enals, and N‐sulfonyl ketimines, in the presence of a slightly different NHC catalytic system. This switchable annulation strategy enables
Enantioselective Activation of Stable Carboxylate Esters as Enolate Equivalents <i>via</i> N-Heterocyclic Carbene Catalysts
作者:Lin Hao、Yu Du、Hui Lv、Xingkuan Chen、Huishen Jiang、Yaling Shao、Yonggui Robin Chi
DOI:10.1021/ol300676w
日期:2012.4.20
The first N-Heterocyclic Carbene (NHC) mediated activation of stable carboxylate esters to generate enolate intermediates is disclosed. The catalytically generated arylacetic ester enolates undergo enantioselective reactions with α,β-unsaturated imines.
Copper-catalyzed conjugate protosilylation reaction of α,β-unsaturated sulfonyl ketimines has been developed. The corresponding E- and Z-stereoselective functionalized allylsilane products were obtained in good yields respectively via tuning the ligands used in the reactions. Furthermore, the highly enantioselective (E)-β-tosylamine-substituted allylsilanes were also achieved in the presence of chiral