- Organocatalytic and enantioselective [4+2] cyclization between hydroxymaleimides and: Ortho -hydroxyphenyl para -quinone methide-selective preparation of chiral hemiketals
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A cinchona alkaloid squaramide promoted enantioselective [4+2] cyclization between hydroxymaleimides and ortho-hydroxyphenyl p-QMs has been disclosed, and a wide range of chiral hemiketals containing chromane and succinimide frameworks with two adjacent quaternary stereogenic centers have been prepared for the first time with excellent results (up to 99% yield, up to 99?:?1 dr, up to >99% ee) under mild conditions. This journal is
- Xiang, Min,Li, Chen-Yi,Song, Xiang-Jia,Zou, Ying,Huang, Zhi-Cheng,Li, Xia,Tian, Fang,Wang, Li-Xin
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supporting information
p. 14825 - 14828
(2020/12/07)
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- Palladium-Catalyzed α-Arylation of Carboxylic Acids and Secondary Amides via a Traceless Protecting Strategy
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A novel traceless protecting strategy is presented for the long-standing challenge of conducting the palladium-catalyzed α-arylation of carboxylic aids and secondary amides with aryl halides. Both of the presented coupling processes occur with a variety of carboxylic acids and amides and with a variety of aryl bromides containing a broad range of functional groups, including base-sensitive functionality like acyl, alkoxycarbonyl, nitro, cyano, and even hydroxyl groups. Five commercial drugs were prepared through this method in one step in 81-96% yield. Gram-scale synthesis of medication Naproxen and Flurbiprofen with low palladium loading further highlights the practical value of this method.
- He, Zhi-Tao,Hartwig, John F.
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supporting information
p. 11749 - 11753
(2019/08/26)
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- Organocatalytic Asymmetric Annulation between Hydroxymaleimides and Nitrosoarenes: Stereoselective Preparation of Chiral Quaternary N-Hydroxyindolines
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An unusual and highly effective asymmetric annulation of nitrosoarenes with hydroxymaleimides catalyzed by a chiral bifunctional amine squaramide catalyst has been disclosed. A wide range of highly fused chiral N-hydroxyindolines with two consecutive quaternary stereocenters and multifunctional groups were directly and effectively prepared in excellent yields (up to >99%) with complete regioselective cyclization and excellent stereoselectivities (up to >99:1 dr and >99% ee). The efficiency and potentials of the new reaction and the target chiral entities were well demonstrated by delicate transformations into a series of new chiral indolines.
- Yang, Yu,Ren, Hong-Xia,Chen, Feng,Zhang, Zheng-Bing,Zou, Ying,Chen, Chao,Song, Xiang-Jia,Tian, Fang,Peng, Lin,Wang, Li-Xin
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supporting information
p. 2805 - 2808
(2017/06/07)
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- Catalytic acylation of amines with aldehydes or aldoximes
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The simple nickel salt NiCl2?6H2O catalyzes the coupling of aldoximes with amines to give secondary or tertiary amide products. The aldoxime can be prepared in situ from the corresponding aldehyde. The use of 18O-labeled oximes has allowed insight into the mechanism of this reaction.
- Allen, C. Liana,Davulcu, Simge,Williams, Jonathan M. J.
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supporting information; experimental part
p. 5096 - 5099
(2011/02/21)
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- Bis(salicylaldehyde)ethylenedi-iminecobalt(II)-catalysed Oxidation of Aromatic Amins with Oxygen
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N-n-Butylanilines undergo N-dealkylation to give a primary amine and butyrylaldehyde by oxidation with oxygen in the presence of bis(salicylaldehyde)ethylenedi-iminecobalt(II) (CoIIsalen) as a catalyst.High conversions are obtained with high catalyst concentrations and low / ratios (r).Inspection of the effect of catalyst and substrate concentrations on initial reaction rates (Vin) shows poor sensitivity to the electronic effect of the nuclear substituent.Some anilines give azo derivatives at a lower rate in the same conditions.
- Benedini, Francesca,Galliani, Guido,Nali, Micaela,Rindone, Bruno,Tollari, Stefano
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p. 1963 - 1968
(2007/10/02)
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