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Sunggi Lee 《Tetrahedron letters》2009,50(26):3345-11452
Binaphthol-derived chiral phosphoric acid catalysts were applied to enantioselective radical addition reactions of imines and provided chiral amines with good enantioselectivities (73-84% ee). Furthermore, the enantioselectivities were not affected by either electronic properties of phenyl imines or radical precursors. 相似文献
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Jan Vesely 《Tetrahedron letters》2007,48(3):421-425
Highly enantioselective catalytic routes to Boc protected β-amino aldehydes, β-amino acids and γ-amino alcohols are presented. The organocatalytic asymmetric reactions between unmodified aldehydes and N-Boc protected aryl imines proceed with excellent chemo- and enantioselectivities to give the corresponding compounds in high yields with up to >19:1 dr and 93% to >99% ee. 相似文献
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Adiseshu Kattuboina 《Tetrahedron letters》2008,49(10):1573-1577
Novel chiral N-phosphonyl imines 2 have been designed and synthesized using chiral N-phosphoramide 1. These N-phosphonyl imines have been successfully utilized for asymmetric aza-Darzens reaction and asymmetric aza-Henry reaction. The C2-symmetric chiral auxiliary tolerates oxidation, is not sensitive to racemization and can be recycled for large scale synthesis. 相似文献
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Isabelle Bonnaventure 《Tetrahedron》2009,65(26):4968-9061
The preparation of N-heterocycles from alkyl- and aryl-substituted imines is described. The key step involves a copper-catalyzed addition of diethylzinc to functionalized alkyl-substituted imines that were generated in situ from the sulfinic acid adducts. The nucleophilic addition products were then converted to 2-substituted pyrrolidines and piperidines. Aryl-substituted imines were transformed into enantioenriched 1- and 1,4-substituted tetrahydroisoquinolines. 相似文献
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Jan Vesely 《Tetrahedron letters》2007,48(39):6900-6904
Highly enantioselective catalytic routes to Boc protected aza-Morita-Baylis-Hillman-type products are presented. The organocatalytic asymmetric reactions between unmodified α,β-unsaturated aldehydes and N-Boc protected aryl imines proceed with excellent chemo- and enantioselectivity to give the corresponding compounds in good yields with 97-99% ee. 相似文献
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A highly efficient protocol has been developed for the synthesis of aminals from γ-butyrolactam and benzaldehyde using iodine as Lewis acid catalyst. The attack of γ-butyrolactam nucleophile to intermediate N-acyliminium ion was more favorable, when aryl aldehyde bears the electron donating group (EDG). Iodine plays a key role in these reaction transformations. This current mild protocol is environmentally benign and cost-effective method for the synthesis of industrially and pharmaceutically useful scaffolds. 相似文献
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David Guijarro 《Tetrahedron letters》2009,50(38):5386-1833
The ruthenium complex prepared from [RuCl2(p-cymene)]2 and (1S,2R)-1-amino-2-indanol is a very efficient catalyst for the asymmetric transfer hydrogenation of (R)-N-(tert-butanesulfinyl)ketimines in isopropanol. By carefully removing all possible moisture from the reaction medium, chiral primary amines with very high optical purities (up to >99% ee) can be easily prepared in excellent yields by the diastereoselective reduction of the imines followed by removal of the sulfinyl group under mild acidic conditions. Reaction times of 1-4 h were needed to complete the reduction reactions when they were performed at 40 °C. 相似文献
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A simple and convenient mechanochemical method for the condensation of aldehydes with tert-butanesulfinamide using catalytic amounts of iodine under metal- and solvent-free conditions is described. 相似文献
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Adiseshu Kattuboina 《Tetrahedron letters》2008,49(23):3722-3724
Chiral N-phosphonyl homoallylic amines were synthesized by the reaction of allylmagnesium bromide with chiral N-phosphonyl imines. The C2-symmetric chiral N-phosphonyl group was optimized for this reaction. Excellent yields and good diastereoselectivities were obtained for eight examples. 相似文献
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Gaurav Bhargava 《Tetrahedron》2008,64(13):3017-3024
The chemo- as well as regioselective imino Diels-Alder reactions of 5-dienyl pyrimidinones with N-aryl as well as N-naphthyl imines in the presence of a different Lewis acid catalysts resulting in novel quinoline and benzoquinoline derivatives are reported. 相似文献
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A new sialyl donor, N,N-dibenzyl-protected p-toluenethiosialoside, was synthesized and its sialylation reaction was investigated. This reaction proceeded in a preactivation manner and preferred to provide β-anomeric coupling products. The β-selectivity was rationalized based on the assumption that N,N-dibenzylamino group could serve as an oriented group to activate the hydroxyl group of acceptor from β-face. 相似文献
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Roman G. KultyshevAkira Miyazawa 《Tetrahedron》2011,67(11):2139-2148
A facile approach to the synthesis of several types of chiral P,N- and P,P-ligands bearing triethoxysilyl groups starting from N,N-diemthyl-1-ferrocenylethylamine (Ugi amine) has been developed. Allyl palladium complexes of these ligands have been prepared, characterized, and grafted on mesoporous silica. The resulting silica-supported complexes have been shown to catalyze asymmetric allylic alkylation and aminations reactions with moderate enantioselectivities. 相似文献
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《Tetrahedron: Asymmetry》2000,11(23):4645-4650
A simple synthesis of two new nitrogen containing diselenides, 7 and 8, is described. These compounds were employed as starting materials to effect the asymmetric methoxyselenenylation, the hydroxyselenenylation as well as the cyclofunctionalization of olefins. Starting from 7 all these addition processes occurred with good facial selectivity. Poor results were however obtained with 8. One-pot selenenylation–elimination sequences using catalytic amounts of the diselenide 7 have also been investigated. 相似文献
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Mlynarski J Rakiel B Stodulski M Suszczyńska A Frelek J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(31):8158-8167
The asymmetric aldol-Tishchenko reaction of aromatic aldehydes with aliphatic and aromatic ketones has been developed as an efficient strategy for the synthesis of anti-1,3-diols in good yield with high diastereocontrol and good levels of enantioselectivity. This domino-type reaction is catalyzed by a chiral ytterbium complex that promotes both the aldol reaction through enolization of the carbonyl compound and the Evans-Tishchenko reduction of the aldol intermediate. The stereochemistry of the resulting diols is also investigated and finally proved by using CD techniques. 相似文献
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A readily available, low cost bifunctional organic catalyst promoted the addition of nitroesters to imines; in the reaction between 2-nitropropionates and N-Boc protected aldehyde-imines the product bearing a new quaternary stereocenter was obtained in up to 81% ee. The positively charged catalyst was postulated to control the attack of the enolic form of nitroester to imine through a hydrogen bonding network. 相似文献