941706-81-6Relevant articles and documents
Mechanistic study of β-substituent effects on the mechanism of ketone reduction by Sml2
Prasad, Edamana,Flowers II, Robert A.
, p. 6357 - 6361 (2002)
The rate constants for the reduction of 2-butanone, methylacetoacetate, N, N-dimethylacetoacetamide, and a series of 4′- and 2′-substituted acetophenone derivatives by Sml2 were determined in dry THF using stopped-flow absorption decay experiments. Activation parameters for the electron-transfer processes in each series of compounds were determined by a temperature-dependence study over a range of 30 to 50 °C. Two types of reaction pathways are possible for these electron-transfer processes. One proceeds through coordination (Scheme 1) while the other involves chelation (Scheme 2). The results described herein unequivocally show that both coordination and chelation provide highly ordered transition states for the electron-transfer process but the presence of a chelation pathway dramatically increases the rate of the reduction of these substrates by Sml2. The ability of various functional groups to promote a chelated reaction pathway plays a crucial role in determining the rate of the reaction. Among the 2′-substituted acetophenone series, the presence of a fluoro, amino, or methoxy substituent enhances the rate of reduction compared to the 4′-analogues. In particular, the presence of a 2′-fluoro substituent on acetophenone provides a highly ordered transition state and considerably enhances the rate of ketone reduction.
Facile Access to Triazole-Fused 3,1-Benzoxazines Enabled by Metal-Free Base-Promoted Intramolecular C-O Coupling
Tatevosyan, Stepan S.,Kotovshchikov, Yury N.,Latyshev, Gennadij V.,Lukashev, Nikolay V.,Beletskaya, Irina P.
supporting information, p. 369 - 377 (2021/10/21)
A convenient approach to assemble 1,2,3-triazole-fused 4 H -3,1-benzoxazines has been developed. Diverse alcohol-tethered 5-iodotriazoles, readily accessible by a modified protocol of Cu-catalyzed (3+2)-cycloaddition, were utilized as precursors of the target fused heterocycles. The intramolecular C-O coupling proceeded efficiently under base-mediated transition-metal-free conditions, furnishing cyclization products in yields up to 96%. Suppression of the competing reductive cleavage of the C-I bond was achieved by the use of Na 2CO 3in acetonitrile at 100 °C. This practical and cost-effective procedure features a broad substrate scope and valuable functional group tolerance.
Effect of solvent in the hydrogenation of acetophenone catalyzed by Pd/S-DVB
Bereta, Tomasz,Mieczyńska, Ewa,Ronka, Sylwia,Tylus, W?odzimierz,Trzeciak, Anna M.
, p. 5023 - 5028 (2021/03/26)
A solvent effect was found in the hydrogenation of acetophenone catalyzed by a new Pd/S-DVB catalyst, immobilized on a styrene (S)/divinylbenzene (DVB) copolymer containing phosphinic groups. The porous structure of the catalyst was characterized by a specific surface area of 94.7 m2g?1. The presence of Pd(ii) and Pd(0) in Pd/S-DVB was evidenced by XPS and TEM. Pd/S-DVB catalyzes the hydrogenation of acetophenone (APh) to 1-phenylethanol (PhE) and ethylbenzene (EtB). The highest conversion of APh was obtained in methanol (MeOH) and in 2-propanol (2-PrOH), while in water it was lower. The conversion of APh correlates well with the hydrogen-bond-acceptance (HBA) capacity of the solvent. However, in all binary mixtures of alcohol and water the APh conversion and the yield of products significantly decreased. The observed inhibiting effect can be explained by the microheterogeneity of these mixtures and the blocking of the catalyst surface restricting access of the substrates to the Pd centers.
Highly selective hydrogenation of aromatic ketones to alcohols in water: effect of PdO and ZrO2
Alsalahi, W.,Trzeciak, A. M.,Tylus, W.
, p. 10386 - 10393 (2021/08/09)
Pd/ZrO2and PdO/ZrO2composites, containing Pd or PdO nanoparticles, were prepared using an original one-step methodology. These nanocomposites catalyze the hydrogenation of acetophenone (AP) at 1 bar and 10 bar of H2in an aqueous solution. Compared to unsupported Pd or PdO nanoparticles, a remarkable increase in their activity was achieved as a result of interaction with zirconia. An unsupported PdO hydrogenated AP mainly to ethylbenzene (EB), while excellent regioselectivity towards 1-phenylethanol (PE) was obtained with PdO/ZrO2and it was preserved during recycling. Similarly, regioselectivity to PE was higher with Pd/ZrO2compared to unsupported Pd NPs. PdO and zirconia resulted in high selectivity to alcohols in the hydrogenation of substituted acetophenones.
