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)
Azonanes were prepared by a palladium-catalyzed (5 + 4) cycloaddition between activated vinylcyclopropanes and 1-azadienes. During this process, the vinylcyclopropane partner displayed an unusual reactivity and behaved as an all-carbon 1,5-dipole. A N,N-bidentate ligand was required to inhibit the formation of thermodynamic (3 + 2) cycloadducts.
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.
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
Sterically and Temperature Controlled Divergent Cycloadditions of α,β‐Unsaturated Imines with Vinylethylene Carbonates: Insights from Experimental and DFT Studies
作者:Xiaolong Xie、Dandan Yuan、Ben Ma、Jiaming Jin、Enpeng Wang、Wenyi Zhou、Yaowen Hu、Lihong Hu、Junwei Wang
DOI:10.1002/adsc.202101423
日期:2022.3.15
Divergent synthesis of heterocycles with controllable ring sizes from the same starting materials is a long-standing challenge. We report herein the first example of controllable divergent [4+5] and [2+3] cycloadditions of α,β-unsaturatedimines and vinylethylene carbonates, which enables the selectively synthesis of nine-membered and different five-membered heterocycles by controlling the reaction