A chiral pyrrolidine-pyrazole catalyst for the enantioselective Michael addition of carbonyls to nitroolefins
摘要:
An enantioselective Michael reaction of carbonyl compounds to nitroolefins has been accomplished using a novel chiral pyrrolidine-pyrazole catalyst. This newly prepared catalyst was found to be very effective in providing good yields as well as good diastereo- and enantio-selectivities. The mechanism of the reaction has also been substantiated by mass spectral studies. (C) 2011 Elsevier Ltd. All rights reserved.
l-Prolinol as a highly enantioselective catalyst for Michael addition of cyclohexanone to nitroolefins
作者:Pei Juan Chua、Bin Tan、Xiaofei Zeng、Guofu Zhong
DOI:10.1016/j.bmcl.2009.03.076
日期:2009.7
versatile catalysts in many reactions, l-prolinol was seldom used as organocatalyst for reactions. Herein, we report the first l-prolinol catalyzed asymmetric Michaeladdition of cyclohexanone to nitroolefins in the presence of benzoic acid to afford Michael adducts with high diastereoselectivities (87:13–>99:1) and enantioselectivities (82–96%).
Chiral pyrrolidine–triazole conjugate catalyst for asymmetric Michael and Aldol reactions
作者:S. Chandrasekhar、Bhoopendra Tiwari、Bibhuti B. Parida、Ch. Raji Reddy
DOI:10.1016/j.tetasy.2008.01.033
日期:2008.3
A new pyrrolidine-triazole conjugate organocatalyst is synthesized using a Huisgen 1,3-dipolar cycloaddition reaction. The application of this catalyst in an asymmetric Michael addition and in an Aldol reaction is described, showing good catalytic activity. The reactions proceeded to give the products in good yield and in a highly selective manner. (C) 2008 Elsevier Ltd. All rights reserved.
Pyrrolidine-oxyimides: new chiral catalysts for enantioselective Michael addition of ketones to nitroolefins in water
A new class of proline based organocatalysts 'pyrrolidine-oxyimides' were designed and synthesized from L-proline and hydroxyimides by employing a simple reaction protocol. These catalysts were found to be efficient in promoting asymmetric Michael additions of ketones to nitroolefins at room temperature. Good yields and high selectivities were obtained with catalyst 1a under additive-free conditions employing water as the reaction medium. (C) 2014 Elsevier Ltd. All rights reserved.
Solvent free, fast and asymmetric Michael additions of ketones to nitroolefins using chiral pyrrolidine–pyridone conjugate bases as organocatalysts
作者:Chandan K. Mahato、Mrinalkanti Kundu、Animesh Pramanik
DOI:10.1016/j.tetasy.2017.03.002
日期:2017.4
New chiral organocatalysts are envisaged based on a pyrrolidine-pyridone conjugate and synthesized from commercially available proline employing standard protocols. These catalysts were found to be useful for asymmetric Michael additions of ketones to nitroolefins to afford the desired products in very good yields (up to 98%) with excellent diastereo- and enantioselectivities (>97:3 syn/anti and up to 98% ee) in very short reaction time compared with the existing reports. (C) 2017 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.