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)
Phosphine-Catalyzed [4 + 1] Annulation between α,β-Unsaturated Imines and Allylic Carbonates: Synthesis of 2-Pyrrolines
作者:Junjun Tian、Rong Zhou、Haiyun Sun、Haibin Song、Zhengjie He
DOI:10.1021/jo200164v
日期:2011.4.1
In this report, a phosphine-catalyzed [4 + 1] annulationbetween α,β-unsaturated imines and allylic carbonates is described. This reaction represents the first realization of catalytic [4 + 1] cyclization of 1,3-azadienes with in situ formed phosphorusylides, which provides highly efficient and diastereoselective synthesis of 2-pyrrolines.
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
DMAP-promoted in situ activation of bromoacetic acid as a 2-carbon synthon for facile synthesis of pyridines and fused pyridin-2-ones
作者:Lu Wang、Gaoyuan Zhu、Weifang Tang、Tao Lu、Ding Du
DOI:10.1016/j.tet.2016.08.062
日期:2016.10
A general and simple synthesis of 2,4,6-trisubstituted pyridines and fused pyridine-2-ones from bromoacetic acid is developed via a DMAP-promoted in situ activation strategy. In this protocol, readily accessible bromoacetic acid has been effectively employed as a 2C synthon to undergo formal [2+4] cycloadditions with diverse acyclic and cyclic 1-azadienes. Low costs of the reagents and materials, mild