Differentiation of the reactivities of carbon-carbon multiple bonds in one molecule. Highly chemo- and stereo-selective hydrohalogenation of allyl or propargyl propiolates
摘要:
The reaction of allyl or propargyl propiolates with lithium halides in acetic acid afforded allyl or propargyl (Z)-3-halopropenoates highly chemo- and stereo-selectively by differentiation of reactivities of carbon-carbon multiple bonds in the same molecule.
Radical Hydrosilylation of Alkynes Catalyzed by Eosin Y and Thiol under Visible Light Irradiation
作者:Jing Zhu、Wei-Chen Cui、Shaozhong Wang、Zhu-Jun Yao
DOI:10.1021/acs.orglett.8b00909
日期:2018.6.1
A visible light-promoted hydrosilylation of alkynes has been explored and achieved using 1 mol % organic dye Eosin Y as the photocatalyst and a catalytic amount of thiol as the radical quencher. The corresponding alkenylsilanes were provided with high regio- and stereoselectivites in the reactions of various terminal and internal alkynes. The experimental evidence shows that the reaction is preferentially
In the presence of a catalytic amount of Cp*RuCl(cod), 1,6-diynes were allowed to react chemo- and regioselectively with electron-deficient nitriles and heterocumulenes at 60−90 °C to afford heterocyclic compounds. The mechanism of the ruthenium-catalyzed regioselective formations of bicyclic pyridines and pyridones were analyzed on the basis of density functional calculations. Cyclocotrimerizations
在催化量的 Cp*RuCl(cod) 存在下,1,6-二炔可以在 60-90 °C 下与缺电子腈和杂枯烯进行化学和区域选择性反应,得到杂环化合物。在密度泛函计算的基础上分析了钌催化的双环吡啶和吡啶酮区域选择性形成的机制。丙炔酸乙酯与氰基甲酸乙酯或异氰酸丙酯的环三聚反应产生四种可能的吡啶或吡啶酮区域异构体中的两种。
Synthesis of Isobenzofuranones by Cobalt Catalyzed [2+2+2] Cycloaddition
Transition metal‐catalyzed [2+2+2] cyclotrimerization is a powerful method to synthesize substituted benzene derivatives with optimal atom efficiency. However, controlling regio‐ and chemoselectivity is difficult. We present a cobalt catalyzed cycloaddition of alkynes, which provides the cycloaddition products in high yields and excellent regioselectivity in the presence of a pyridine‐2,6‐diimine ligand
A series of fluoroalkylated 1,4-disubstituted [1,2,3]-triazoles were synthesized by the 1,3-dipolar cycloaddition of fluoroalkylated azides with terminal alkynes in the presence of Cu(I) salt as catalyst at room temperature. All the reactions were performed in highly regioselective with 1,4-disubstituted, no 1,5-disubstituted product was formed. For aryl or alkyl-alkyne, triethylamine should be used
annulation of 2-iodo enol esters leading to 4- and 3,4-substituted isocoumarins was accomplished selectively at room temperature. Coupling of 2-iodo benzoic acids with enolates that were produced in situ from the simple esters was also performed to produce isocoumarins under analogous reaction conditions. Owing to the mildness of the current protocol, 4-acyl 3-substitutedisocoumarins were efficiently produced