34233-75-5Relevant academic research and scientific papers
Catalytic asymmetric difunctionalization of stable tertiary enamides with salicylaldehydes: Highly efficient, enantioselective, and diastereoselective synthesis of diverse 4-chromanol derivatives
He, Ling,Zhao, Liang,Wang, De-Xian,Wang, Mei-Xiang
, p. 5972 - 5975 (2014)
Catalyzed by a chiral BINOL-Ti(OiPr)4 complex, various stable tertiary enamides reacted with salicylaldehydes to afford diverse cis,trans-configured 4-chromanols that contain three continuous stereogenic centers in good yields with excellent diastereoselectivity and enantioselectivity. The reaction proceeded through the addition of enamide to aldehyde followed by the intramolecular interception of the resulting iminium by the hydroxy group. Oxidation of the resulting 4-chromanols yielded almost quantitatively chroman-4-one derivatives which underwent diastereospecific reduction with NaBH4 to produce cis,cis-configured 4-chromanols.
Monoacylation of Symmetrical Diamines in Charge Microdroplets
Ansu-Gyeabourh, Emelia,Amoah, Enoch,Ganesa, Chandrashekar,Badu-Tawiah, Abraham K.
, p. 531 - 536 (2021/01/13)
Monoacylation of symmetrical diamine is achieved when the primary α,ω-diamines (carbon numbers n = 3, 5 and 12) are diluted in ethyl acetate, and the resultant mixture is electrosprayed across a 10 mm distance in ambient air toward a mass spectrometer. The N-acylated product is formed in charged microdroplets without acidifying and activating agents and in the absence of heat. This result provided an insight into the orientation of the amines in the droplets, suggesting that the ester is activated to react with the amine at the droplet surface due to the high abundance of protons at the air-droplet interface.
Base-Free Oxidative Coupling of Amines and Aliphatic Alcohols to Imines over Au–Pd/ZrO2 Catalyst under Mild Conditions
Cui, Wenjing,Jia, Meilin,Sagala,Wang, Jiang
, p. 958 - 967 (2021/06/06)
Abstract: The base-free synthesis of imines from amines and aliphatic alcohols over Au–Pd alloy catalysts under ambient conditions was developed. A series of Au–Pd/ZrO2 bimetallic catalysts with varying metal loadings and Au?:?Pd molar ratios were prepared and their catalytic performance was investigated. The 3.0?wt?% Au–Pd/ZrO2 alloy catalyst with Au?:?Pd molar ratio of 1?:?1 showed the best catalytic performance. Under air atmosphere, various imines were obtained from coupling of amines and aliphatic alcohols without any additives or promoters. The performance of alloy NPs was superior to that of monometallic catalysts due to the synergistic effect which was demonstrated by TEM, XPS, and UV–Vis characterization. Our work suggested this transformation differed slightly from those reactions between amine and benzyl alcohol and a possible mechanism was proposed. Moreover, the Au–Pd/ZrO2 catalyst could be easily separated and reused for at least five successive runs with high catalytic activity.
Enantioselective Reductive Cyanation and Phosphonylation of Secondary Amides by Iridium and Chiral Thiourea Sequential Catalysis
Chen, Dong-Huang,Sun, Wei-Ting,Zhu, Cheng-Jie,Lu, Guang-Sheng,Wu, Dong-Ping,Wang, Ai-E,Huang, Pei-Qiang
supporting information, p. 8827 - 8831 (2021/03/16)
The combination of transition-metal catalysis and organocatalysis increasingly offers chemists opportunities to realize diverse unprecedented chemical transformations. By combining iridium with chiral thiourea catalysis, direct enantioselective reductive cyanation and phosphonylation of secondary amides have been accomplished for the first time for the synthesis of enantioenriched chiral α-aminonitriles and α-aminophosphonates. The protocol is highly efficient and enantioselective, providing a novel route to the synthesis of optically active α-functionalized amines from the simple, readily available feedstocks. In addition, the reactions are scalable and the thiourea catalyst can be recycled and reused.
Aza-Henry reactions on C-Alkyl substituted aldimines
Pelagalli, Alessia,Pellacani, Lucio,Scandozza, Elia,Fioravanti, Stefania
, (2016/07/07)
The reactivity of C-CH3 substituted N-protected aldimines in aza-Henry addition reactions was compared with that of the analogous trifluoromethylated compounds. C-Alkyl aldimines easily reacted with nitro alkanes under solvent-free conditions and in the absence of catalyst, despite being worse electrophiles than C-CF3 aldimines, they gave the aza-Henry addition only when ZrCl4 was added. The presence of a bulky group on the imine carbon deeply influenced the reactivity.
Axially Chiral Enamides: Substituent Effects, Rotation Barriers, and Implications for their Cyclization Reactions
Clark, Andrew J.,Curran, Dennis P.,Fox, David J.,Ghelfi, Franco,Guy, Collette S.,Hay, Benjamin,James, Natalie,Phillips, Jessica M.,Roncaglia, Fabrizio,Sellars, Philip B.,Wilson, Paul,Zhang, Hanmo
, p. 5547 - 5565 (2016/07/14)
The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG∞ rotation varied between -1). The most important factor in controlling the rate of rotation was the level of alkene substitution, followed by the size of the nitrogen substituent and, finally, the size of the acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for rotation between 5.5 days and 99 years at 298 K, sufficient to isolate enantiomerically enriched atropisomers. The radical cyclizations of a subset of N-alkenyl-N-benzyl-α-haloacetamides exhibiting relatively high barriers to rotation round the N-alkenyl bond (ΔG∞ rotation >20 kcal mol-1) were studied to determine the regiochemistry of cyclization. Those with high barriers (>27 kcal mol-1) did not lead to cyclization, but those with lower values produced highly functionalized γ-lactams via a 5-endo-trig radical-polar crossover process that was terminated by reduction, an unusual cyclopropanation sequence, or trapping with H2O, depending upon the reaction conditions. Because elevated temperatures were necessary for cyclization, this precluded study of the asymmetric transfer in the reaction of individual atropisomers. However, enantiomerically enriched atropsiomeric enamides should be regarded as potential asymmetric building blocks for reactions that can be accomplished at room temperature.
Convenient modular construction of medicinally important 5-acylamino-4,5-dihydroisoxazoles featuring four elements of diversity
Kulyashova, Alexandra,Krasavin, Mikhail
supporting information, p. 4395 - 4397 (2016/09/13)
An efficient modular approach toward medicinally important 5-acylamino-4,5-isoxazolines via the 1,3-dipolar cycloaddition reaction of nitrile oxides and MCR-derived enamide building blocks is described. This approach results in isoxazolines containing four elements of diversity utilizing two practically simple synthetic operations.
Synthesis of imines from amines in aliphatic alcohols on Pd/ZrO2 catalyst under ambient conditions
Cui, Wenjing,Zhaorigetu, Bao,Jia, Meilin,Ao, Wulan,Zhu, Huaiyong
, p. 2601 - 2604 (2014/01/06)
Synthesis of imines from amines and aliphatic alcohols (C 1-C6) in the presence of base on supported palladium nanoparticles has been achieved for the first time. The catalytic system shows high activity and selectivity in open air at room temperature.
Substituted 4-Oxo-1,2,3,4-tetrahydroquinoline-3-carboxylic esters by a tandem imine addition-SNAr reaction
Bunce, Richard A.,Schammerhorn, James E.,Sigle, Jessica
, p. 373 - 380 (2013/06/04)
A tandem imine addition-SNAr annulation reaction has been developed as a new approach to the synthesis of 4-oxo-1,2,3,4- tetrahydroquinoline-3-carboxylic esters. A series of these structures has been generated by reacting selected imines with tert-butyl 2-fluoro-5- nitrobenzoylacetate. Structural variations in the final products are accomplished by changing the substituents on the imine and the alkyl group of the ester. The title compounds are isolated as their enols in 55-97% yield without the need for added base or catalysts. The synthesis of the starting materials as well as mechanistic studies and further synthetic conversions of the products are presented.
Coupling of two multistep catalytic cycles for the one-pot synthesis of propargylamines from alcohols and primary amines on a nanoparticulated gold catalyst
Corma, Avelino,Navas, Javier,Sabater, Maria J.
, p. 14150 - 14156 (2013/01/15)
A one-pot reaction was performed with a nanoparticulated gold catalyst. A secondary amine is formed through N-monoalkylation of a primary amine with an alcohol by a borrowing hydrogen methodology in a three-step reaction. The secondary amine formed enters into a second A3-coupling cycle to give propargylamines. The multistep reaction requires a gold species formed and stabilized on a ceria surface. Copyright
