Lipase/Acetamide-Catalyzed Carbon-Carbon Bond Formations: A Mechanistic View
作者:Xiao-Yang Chen、Guo-Jun Chen、Jun-Liang Wang、Qi Wu、Xian-Fu Lin
DOI:10.1002/adsc.201201080
日期:2013.3.25
A lipase B from Candida antarctica (CALB)/acetamide‐catalyzed Michael addition of less‐activated ketones and aromatic nitroolefins has been developed, which is particularly interesting because neither CALB nor acetamide can independently catalyze the reaction to any appreciable extent. This co‐catalyst system was applicable to the Michael additions of cyclic and acyclic ketones to a series of aromatic
trifunctional catalyst was successfully prepared by bonding (1R,2R)-(+)-1,2-DPEN to sulfonic acidresin. The catalyst was characterized by elemental analysis, thermogravimetric (TG) analysis and infrared (IR) spectroscopy. The results indicated the coexistence of sulfonic, sulfonamido and primary amino groups on the surface of the resin. Based on the IR spectroscopy of the catalyst treated with a solution
Some novel prolinal dithioacetal derivatives have been synthesized and applied as the organocatalysts for the direct Michaeladdition of ketones and aldehydes to nitroalkenes. High enantioselectivities and diastereoselectivities have been obtained in both organic and aqueous media (dichloromethane, water, or brine).
Organocatalyzed asymmetric Michael addition by an efficient bifunctional carbohydrate–thiourea hybrid with mechanistic DFT analysis
作者:Chandra S. Azad、Imran A. Khan、Anudeep K. Narula
DOI:10.1039/c6ob02158a
日期:——
core scaffold were synthesized and examined as catalysts for the asymmetricMichael addition reaction of aryl/alkyl trans-β-nitrostyrenes over cyclohexanone and other Michael donors having active methylene. Excellent enantioselectivities (<95%), diastereoselectivities (<99%), and yields (<99%) were attained undersolvent free conditions using 10 mol% of 1d0. The obtained results were explained through
Michaeladditions of different aldehydes and ketones to β-nitrostyrene and 2-(β-nitrovinyl)thiophene in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) were studied. β-Nitrostyrene was a better acceptor than 2-(β-nitrovinyl)thiophene, in terms of both reactivity and selectivity. Aldehydes proved to be better donors than ketones, which were themselves better than β-diketones. L-proline proved