نتایج جستجو برای: enamine formation
تعداد نتایج: 527727 فیلتر نتایج به سال:
Based on the enamine reaction, cellulose-based (CAA-PEA) UV shielding film was prepared by solvent pouring.
Experimental and computational studies probing the nature of intermediates in the α-amination of aldehydes catalyzed by prolinate salts support an enamine carboxylate intermediate in the stereodetermining step.
Acylation reaction of a variety of cyclic ketones via acylation of the corresponding enamines is welldefined in the literature. Enamine acylation of carbonyl compounds is a significant synthetic method because of its mildness and the ease of preparing various β-diketones [1-4]. Acylation reactions are performed by means of converting enamines to the enaminoketones and subsequent hydrolysis of t...
The mechanism and stereoselectivity in an organocatalyzed triple cascade reaction between an aldehyde, electron deficient olefin and an alpha,beta-unsaturated aldehyde are investigated for the first time using density functional theory. The factors responsible for high levels of observed stereoselectivity (Enders et al., Nature, 2006, 441, 861) towards the generation of cyclohexene carbaldehyde...
The Michael addition of nitromethane to cinnamaldehyde has been computationally studied in the absence of a catalyst and the presence of a biotinylated secondary amine by a combined computational and experimental approach. The calculations were performed at the density functional theory (DFT) level with the M06-2X hybrid functional, and a polarizable continuum model has been employed to mimic t...
Equilibria between carbonyl compounds and their enamines (from O-TBDPS-derived prolinol) have been examined by NMR spectroscopy in DMSO-d(6). By comparing the exchange reactions between pairs (enamine A + carbonyl B → carbonyl A + enamine B), a quite general scale of the tendency of carbonyl groups to form enamines has been established. Aldehydes quickly give enamines that are relatively more s...
The formation of keto-enamine based crystalline, porous polymers in water is investigated for the first time. Facile access to the Schiff base reaction in water has been exploited to synthesize stable porous structures using the principles of Dynamic Covalent Chemistry (DCC). Most credibly, the water-based Covalent Organic Frameworks (COFs) possess chemical as well as physical properties such a...
Mannich reactions between aldehydes and N-p-methoxyphenyl-protected alpha-imino ethyl glyoxylate have been performed using (S)-pipecolic acid as catalyst. The reactions give both syn- and anti-products (dr=1.4-2:1) with high enantioselectivities (>98% ee). In contrast, (S)-proline-catalyzed reactions give mainly syn-products with high enantioselectivities. Computational studies reveal that the ...
Chiral 1,2-amino alcohols and 1,2-diols are common structural motifs found in a vast array of natural and biologically active molecules.1 Recently, significant efforts have been applied toward the development of direct catalytic asymmetric approaches to the construction of these units based on the addition of unmodified R-hydroxyketones to imines or aldehydes in Mannich-type and aldol reactions...
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