Pyrrolidine-HOBt: an oxytriazole catalyst for the enantioselective Michael addition of cyclohexanone to nitroolefins in water
摘要:
A new analogue of the proline derived organocatalyst 'pyrrolidine-HOBt' has been designed and synthesized from L-prolinol and hydroxybenzotriazole (HOBt) employing a simple reaction protocol. The catalyst was found to be effective in promoting the asymmetric Michael addition of cyclohexanone to nitroolefins using water as the reaction medium. The reaction products gamma-nitrocarbonyls are obtained in good yields and stereoselectivities. (C) 2016 Elsevier Ltd. All rights reserved.
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
A surfactant-type asymmetric organocatalyst (STAO) catalyzed highly efficient Michael addition to nitroalkenes with high stereoselectivities in water without using any organic solvents or additional additives.
combinatorial screening of optimal catalysts for the targeted reactions. In this regard, highly efficient and enantioselective heterogeneous catalysts were identified for the asymmetric direct aldol and Michaeladditionreactions. The catalysts could be easily recovered by filtration and reused for six cycles with similar stereoselectivity but slightly decreased activity. Significantly, the deactivated
Sugar amide-pyrrolidine catalyst for the asymmetric Michael addition of ketones to nitroolefins
作者:Togapur Pavan Kumar、Sirinyam Venugopal Balaji
DOI:10.1016/j.tetasy.2014.02.003
日期:2014.3
New sugar amide-pyrrolidine derivatives possessing the furano form of the carbohydrate template were designed and developed as efficient and stereoselective organocatalysts for asymmetric Michael additions of ketones to nitroolefins at room temperature. Good yields and high selectivities were achieved with catalyst 2 under solvent-free and additive-free reaction conditions. (C) 2014 Elsevier Ltd. All rights reserved.
Pyrrolidine-HOBt: an oxytriazole catalyst for the enantioselective Michael addition of cyclohexanone to nitroolefins in water
A new analogue of the proline derived organocatalyst 'pyrrolidine-HOBt' has been designed and synthesized from L-prolinol and hydroxybenzotriazole (HOBt) employing a simple reaction protocol. The catalyst was found to be effective in promoting the asymmetric Michael addition of cyclohexanone to nitroolefins using water as the reaction medium. The reaction products gamma-nitrocarbonyls are obtained in good yields and stereoselectivities. (C) 2016 Elsevier Ltd. All rights reserved.