21327-72-0Relevant academic research and scientific papers
A Fast and General Route to Ketones from Amides and Organolithium Compounds under Aerobic Conditions: Synthetic and Mechanistic Aspects
Ghinato, Simone,Territo, Davide,Maranzana, Andrea,Capriati, Vito,Blangetti, Marco,Prandi, Cristina
, p. 2868 - 2874 (2021/01/21)
We report that the nucleophilic acyl substitution reaction of aliphatic and (hetero)aromatic amides by organolithium reagents proceeds quickly (20 s reaction time), efficiently, and chemoselectively with a broad substrate scope in the environmentally responsible cyclopentyl methyl ether, at ambient temperature and under air, to provide ketones in up to 93 % yield with an effective suppression of the notorious over-addition reaction. Detailed DFT calculations and NMR investigations support the experimental results. The described methodology was proven to be amenable to scale-up and recyclability protocols. Contrasting classical procedures carried out under inert atmospheres, this work lays the foundation for a profound paradigm shift of the reactivity of carboxylic acid amides with organolithiums, with ketones being straightforwardly obtained by simply combining the reagents under aerobic conditions and with no need of using previously modified or pre-activated amides, as recommended.
Kinetically Controlled, Highly Chemoselective Acylation of Functionalized Grignard Reagents with Amides by N?C Cleavage
Li, Guangchen,Szostak, Michal
supporting information, p. 611 - 615 (2020/01/02)
The direct transition-metal-free acylation of amides with functionalized Grignard reagents by highly chemoselective N?C cleavage under kinetic control has been accomplished. The method offers rapid and convergent access to functionalized biaryl ketones through transient tetrahedral intermediates. The direct access to functionalized Grignard reagents by in situ halogen–magnesium exchange promoted by the versatile turbo-Grignard reagent (iPrMgCl?LiCl) permits excellent substrate scope with respect to both the amide and Grignard coupling partners. These reactions enable facile, operationally simple and chemoselective access to tetrahedral intermediates from amides under significantly milder conditions than chelation-controlled intermediates. This novel direct two-component coupling sets the stage for using amides as acylating reagents in an alternative paradigm to the metal-chelated approach, acyl metals and Weinreb amides.
HMPA-catalyzed transfer hydrogenation of 3-carbonyl pyridines and other N-heteroarenes with trichlorosilane
Fu, Yun,Sun, Jian
supporting information, (2019/02/06)
A method for the HMPA (hexamethylphosphoric triamide)-catalyzed metal-freetransfer hydrogenation of pyridines has been developed. The functional group tolerance of the existing reaction conditions provides easy access to various piperidines with ester or ketone groups at the C-3 site. The suitability of this method for the reduction of other N-heteroarenes has also been demonstrated. Thirty-three examples of different substrates have been reduced to designed products with 45–96% yields.
Preparation of Polyfunctional Organozinc Halides by an InX3- and LiCl-Catalyzed Zinc Insertion to Aryl and Heteroaryl Iodides and Bromides
Benischke, Andreas D.,Le Corre, Grégoire,Knochel, Paul
supporting information, p. 778 - 782 (2017/02/05)
A catalytic system consisting of InCl3(3 mol %) and LiCl (30 mol %) allows a convenient preparation of polyfunctional arylzinc halides via the insertion of zinc powder to various aryl iodides in THF at 50 °C in up to 95 % yield. The use of a THF/DMPU (1:1) mixture shortens the reaction rates and allows the preparation of keto-substituted arylzinc reagents. In the presence of In(acac)3(3 mol %) and LiCl (150 mol %), the zinc insertion to various aryl and heteroaryl bromides proceeds smoothly (50 °C, 2–18 h). Alkyl bromides are also converted to the corresponding zinc reagents in the presence of In(acac)3(10 mol %) and LiCl (150 mol %) in 70–80 % yield.
Synthesis of bis(heteroaryl) ketones by removal of benzylic CHR and CO groups
Maji, Arun,Rana, Sujoy,Akanksha,Maiti, Debabrata
supporting information, p. 2428 - 2432 (2014/03/21)
A copper-catalyzed method for synthesis of diaryl ketones (Ar-CO-Ar′) through removal of benzylic -CH2-, -CO-, and -CHR- groups from Ar-CO-CXR-Ar′ has been discovered. A number of symmetrical and unsymmetrical heterocyclic ketones, which are usually difficult to synthesize, can be prepared in good to excellent yields. This method was applied to the synthesis of the nonsteroidal anti-inflammatory drug suprofen (47 % yield over three steps). Based on preliminary mechanistic and kinetic studies, an active Cu/O2 species is proposed to mediate the rearrangement reaction. Snip snip: A copper-catalyzed method for synthesis of diaryl ketones by removal of benzylic CH2, CO, and CHR groups has been discovered. A number of symmetrical and unsymmetrical heterocyclic ketones, which are usually difficult to synthesize, can be prepared in good to excellent yields. Preliminary mechanistic studies indicate that an active Cu/O2 species mediates the rearrangement. Copyright
Imidazolines as efficacious glucose-dependent stimulators of insulin secretion
Jakobsen, Palle,Madsen, Peter,Andersen, HenrikSune
, p. 357 - 362 (2007/10/03)
Synthesis of a series of imidazolines with glucose dependent effects on insulin exocytosis from pancreatic β-cells is reported. Regioisomers and enantiomers were found to exhibit marked differences in exocytotic effects as well as different activities on the KATP-channel; the (R (+)) isomer of 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-thiophene-2-ylethyl]pyridin e (4a) and the (+) isomer of 2-[2-(4,5-dihydro-1H-imidazol-2-yl)-1-thiophene-3-ylethyl]pyridin e (4d) were found to give a significant increase in insulin release - in contrast to findings for their enantiomers - without influence on the KATP-channel. The (+) isomer (4a) showed glucose dependent insulin release from β-cells at concentrations above 2.5 mM and a marked glucose lowering effect in ob/ob mice as well as in fed but not in fasted rats.
Oral hypoglycaemic agents
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, (2008/06/13)
Compounds of formula (I) which are optionally substituted 2-(ω,ω-diarylalkyl)-4,5-dihydro-1H-imidazoles and 2-(ω,ω-diarylalkyl)-1,4,5,6-tetrahydropyrimidines and salts thereof with inorganic and organic acids have interesting pharmacological properties. T
