Nickel-Catalyzed Cycloaddition of Unsaturated Hydrocarbons and Carbonyl Compounds
作者:Thomas N. Tekevac、Janis Louie
DOI:10.1021/ol0515558
日期:2005.9.1
A mild and general route for preparing pyrans and dienones from carbonyls and diynes is described. Ni imidazolylidene complexes were used to mediate cyclizations between diynes and aldehydes. The reaction of an enyne and an aldehyde afforded a mixture of cyclized products. In addition, a spiropyran was prepared from the cycloaddition of a diyne and cyclohexanone. [reaction: see text]
Cationic Rhodium(I)/Segphos-Catalyzed Cycloisomerization of 1,6- and 1,7-Diynes in the Presence of 1,2-Cyclohexanedione
作者:Ken Tanaka、Yousuke Otake、Masao Hirano
DOI:10.1021/ol7015687
日期:2007.9.1
We have developed the first catalytic cycloisomerization of 1,6- and 1,7-diynes leading to trienes and vinylpyrroles by using a cationic rhodium(I)/Segphos complex (2.5-10 mol %) and 1,2-cyclohexanedione (100 mol %). 1,2-Cyclohexanedione may effectively occupy vacant coordination sites and thus promote the present cycloisomerization.
Highly Stereo- and Regioselective Hydrocarboxylation of Diynes with Carbon Dioxide
作者:Tao Cao、Shengming Ma
DOI:10.1021/acs.orglett.6b00028
日期:2016.4.1
A nickel-catalyzed three-component hydrocarboxylation of diynes with ZnEt2 and CO2 (1 atm) is disclosed. With this method, symmetric/nonsymmetric diynes could be reacted smoothly with very high stereo- and regioselectivity, affording conjugated 2,4-alkadienoic acids incorporated with five- or six-membered rings efficiently. A stepwise non-oxidative cyclometalation mechanism was proposed based on careful
Nickel-Catalyzed Cycloadditions of Unsaturated Hydrocarbons, Aldehydes, and Ketones
作者:Thomas N. Tekavec、Janis Louie
DOI:10.1021/jo702508w
日期:2008.4.1
The nickel-catalyzed cycloaddition of unsaturated hydrocarbons and carbonyls is reported. Diynes and enynes were used as coupling partners. Carbonyl substrates include both aldehdyes and ketones. Reactions of diynes and aldehydes afforded the [3,3] electrocyclic ring-opened tautomers, rather than pyrans, in high yields. The cycloaddition reaction of enynes and aldehydes afforded two distinct products
报道了镍催化的不饱和烃和羰基化合物的环加成反应。二炔和烯炔用作偶联伙伴。羰基底物包括醛和酮。二炔和醛的反应以高产率提供了 [3,3] 电环开环互变异构体,而不是吡喃。烯炔和醛的环加成反应得到两种不同的产物。在烷氧基镍的竞争性β-氢消除之前,在羰基碳与烯烃或炔烃的碳之一之间形成新的碳-碳键。烯炔的空间位阻极大地影响了烯炔和醛环加成的化学选择性。在某些情况下,还会形成二氢吡喃。环加成反应的范围扩大到包括烯炔和酮的偶联。在烯炔和酮的环加成反应中没有观察到β-氢消除。相反,形成 CO 键的还原消除专门用于以优异的产率提供二氢吡喃。在所有情况下,都观察到了完全的化学选择性;只有二氢吡喃的羰基碳与观察到烯烃,而不是炔烃。所有环加成反应均在室温下进行,并使用带有受阻 1,3-双(2,6-二异丙基苯基)咪唑-2-亚基 (IPr) 或其饱和类似物 1,3-双(2,6-二异丙基苯基) 的镍催化剂)-4,5-二氢咪唑啉-2-亚基(SIPr)。