The highly stereoselective allylicalkylation of Morita–Baylis–Hillman carbonates with β-ketoesters catalysed by β-ICD is described. The corresponding products containing two adjacent quaternary and tertiary carbon centers were obtained in good yields with high diastereoselectivity (up to 10 : 1 dr) and enantioselectivity (up to 95% ee).
1,3,5-Triaza-7-phosphaadamantane (PTA): A Practical and Versatile Nucleophilic Phosphine Organocatalyst
作者:Xiaofang Tang、Bo Zhang、Zhengrong He、Ruili Gao、Zhengjie He
DOI:10.1002/adsc.200700071
日期:2007.8.6
cycloaddition reaction of 4-substituted 2,3-butadienoates with N-tosylimines, PTA is also proven to be a comparable catalyst as tributylphosphine (PBu3). By systematic comparison with other structurally similar N,P catalysts, it is concluded that the superiority of PTA in the above nucleophilic catalysis is attributable to its comparable nucleophilicity with that of trialkylphosphines. The feasibility
Efficient Baylis−Hillman Reactions of Cyclic Enones in Methanol As Catalyzed by Methoxide Anion
作者:Sanzhong Luo、Xueling Mi、Hui Xu、Peng George Wang、Jin-Pei Cheng
DOI:10.1021/jo0491760
日期:2004.11.1
The Baylis−Hillman reactions of cyclic enones with a variety of aldehydes were investigated. 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) was found to be a viable catalyst in promoting the reactions of sterically retarded substrates in methanol. The reactions showed clear solvent dependence and only occurred in hydroxylic solvents, especially in methanol. Further consideration on the steric character of
Remarkable Rate Acceleration of Imidazole-Promoted Baylis−Hillman Reaction Involving Cyclic Enones in Basic Water Solution
作者:Sanzhong Luo、Peng George Wang、Jin-Pei Cheng
DOI:10.1021/jo035345p
日期:2004.1.1
The Baylis−Hillmanreaction of cyclic enones was greatly accelerated in basic water solution with imidazoles as catalysts, which resulted in short reaction time, high yields, and expanding substrate scopes. Bicarbonate solution was shown to be the optimal reaction medium for the reaction in this study. The apparent “enhanced basicity” of imidazoles accounted for the rate increase in alkaline solution
Rate Acceleration of the Baylis−Hillman Reaction in Polar Solvents (Water and Formamide). Dominant Role of Hydrogen Bonding, Not Hydrophobic Effects, Is Implicated
作者:Varinder K. Aggarwal、David K. Dean、Andrea Mereu、Richard Williams
DOI:10.1021/jo016073y
日期:2002.1.1
A substantial acceleration of the Baylis-Hillmanreaction between cyclohexenone and benzaldehyde has been observed when the reaction is conducted in water. Several different amine catalysts were tested, and as with reactions conducted in the absence of solvent, 3-hydroxyquinuclidine was found to be the optimum catalyst in terms of rate. The reaction has been extended to other aldehyde electrophiles