The highly chemo- and enantioselective organocatalytic tandem reaction between N-carbamate-protected hydroxylamines and α,β-unsaturated aldehydes is presented. The reaction represents a unique entry for the asymmetric synthesis of 5-hydroxyisoxazolidines, oxazolidin-5-ones or γ-hydroxyamino alcohols in high yields and 90-99% ee. A procedure for the conversion of the oxazolidin-5-ones into the corresponding β-amino acids is also described.
Chiral Ionic Liquid/ESI‐MS Methodology as an Efficient Tool for the Study of Transformations of Supported Organocatalysts: Deactivation Pathways of Jørgensen–Hayashi‐Type Catalysts in Asymmetric Michael Reactions
作者:Oleg V. Maltsev、Alexander O. Chizhov、Sergei G. Zlotin
DOI:10.1002/chem.201100388
日期:2011.5.23
organocatalysts modified with an ionic liquid fragment in asymmetric Michaelreactions of α,β‐enals with C‐ (nitromethane, dimethylmalonate) or N‐nucleophiles (N‐carbobenzyloxyhydroxylamine) that involved an iminium‐ion formation step were studied for the first time by the electrospray ionization mass spectrometry (ESI‐MS). “Parasitic” side reactions and undesirable cation intermediates that poisoned the catalysts
Spiro-Pyrrolidine-Catalyzed Asymmetric Conjugate Addition of Hydroxylamine to Enals and 2,4-Dienals
作者:Qing-Yun Dou、Yong-Qiang Tu、Ye Zhang、Jin-Miao Tian、Fu-Min Zhang、Shao-Hua Wang
DOI:10.1002/adsc.201501025
日期:2016.3.17
A spiro‐pyrrolidine‐catalyzed tandem aza‐1,4‐addition/hemi‐acetalization reaction was developed with excellent enantioselectivity (12 examples of ≥99% ee), and several substrates proceeded with higher ee (up to 10% increase) compared with the literature data. Particularly, an interesting and unusual aza‐1,6‐/oxa‐1,4‐addition for some substrates was also observed.
The asymmetricsynthesis of Maraviroc (UK‐427,857), a chemochine receptor 5 (CCR‐5) receptor antagonist, based on an expeditious organocatalytic enantioselective assembly of the chiral β‐amino aldehyde key fragment is presented. The reactions were performed on a gram‐scale and allow for the rapid construction of new Maraviroc analogues.
Immobilization of <i>cis</i>
-4-Hydroxydiphenylprolinol Silyl Ethers onto Polystyrene. Application in the Catalytic Enantioselective Synthesis of 5-Hydroxyisoxazolidines in Batch and Flow
作者:Junshan Lai、Sonia Sayalero、Alessandro Ferrali、Laura Osorio-Planes、Fernando Bravo、Carles Rodríguez-Escrich、Miquel A. Pericàs
DOI:10.1002/adsc.201800572
日期:2018.8.6
A new family of polystyrene‐supported cis‐4‐hydroxydiphenylprolinol silyl ethers has been prepared, and the resulting polymers have been evaluated as organocatalysts to promote the tandem reaction between N‐protected hydroxylamines and α,β‐unsaturated aldehydes in batch and flow. The new PS‐supported catalysts compare favorably with well‐established immobilized Jørgensen‐Hayashi catalysts, affording