A Concise Assembly of Electron-Deficient 2,4-Dienes and 2,4-Dienals: Regio- and Stereoselective<i>exo</i>-Diels-Alder and Redox Reactions through Sequential Amine and Carbene Catalysis
catalysis: A γ,δ‐regioselective anomalous exo‐Diels–Alder reaction with electron‐deficient β‐substituted 2,4‐dienes and 2,4‐dienals has been developed by using trienamine activation. The resulting multifunctional cycloadducts contain perfectly positioned functional groups, thereby facilitating a 1,5‐hydride transfer from the C–H group of an aldehyde to an activated alkene under sequential catalysis of
Chiral phosphine-catalyzed asymmetric [4 + 1] annulation of polar dienes with allylic derivatives: Enantioselective synthesis of substituted cyclopentenes
作者:Hanyuan Li、Zhengjie He
DOI:10.1016/j.tetlet.2021.152863
日期:2021.3
A chiral phosphine-catalyzedasymmetric [4 + 1] annulation reaction of polar 1,3-dienes and allylic derivatives is reported. Under the catalysis of P-chiral bicyclic phosphine (15 mol%), a series of 1,1-dicyano-2,4-diaryl-1,3-dienes (21 examples) readily undergo stereoselective [4 + 1] annulation reactions with allylic acetate under mild conditions, delivering enantio-enriched polysubstituted cyclopentenes
An asymmetric direct ϵ-regioselective bisvinylogous 1,6-addition reaction of β-allyl-2-cyclohexenone to β-substituted α,α-dicyanodienes was developed throughtrienaminecatalysis of a bifunctional primary amine–thiourea compound. Excellent enantioselectivity (up to 97 % ee) was obtained even through such a remote reaction mode. In addition, more complex cyclic frameworks could be efficiently constructed
Highly Substituted Cyclohexenes via Phosphine-Catalyzed [4+2] Annulation of Electron-deficient Dienes and Vinyl Ketones
作者:Peng Chen、Junyou Zhang、Junliang Zhang
DOI:10.1002/adsc.201701168
日期:2018.2.15
A highly efficient phosphine‐catalyzed [4+2] annulation of electron‐deficient diene and alkyl vinyl ketone was developed for the first time, which provides an easy access to functionalized cyclohexenes. This method has the advantages of mild reaction conditions, widely functional group tolerance, high yields and transition metal free.
Organocatalytic Domino Reaction of Electron-Deficient 2,4-Dienes with 2-Halo-1,3-Dicarbonyl Compounds: A Highly Regio- and Stereoselective Approach to Functionalized Five-Membered Carbocycles
AbstractAn unexpected domino reaction of electron‐deficient 2,4‐dienes with 2‐halo‐1,3‐dicarbonyl compounds, employing the readily available N‐(4‐trifluoromethylbenzyl)cinchonium bromide as the phase‐transfer catalyst, provides an access to functionalized cyclopentenes and fulvene derivatives with excellent regio‐, chemo‐ and stereoselectivities. A plausible mechanism for this unprecedented domino reaction is given.magnified image