194540-36-8Relevant articles and documents
An expedient synthesis of cyanoformates via DAST-mediated C–C bond cleavage of α-oximino-β-ketoesters
Kim, Danhee,Lim, Hee Nam
, (2021/05/10)
A new protocol to synthesize cyanoformates was developed using simple β-ketoesters as substrates. (Diethylamino)sulfur trifluoride (DAST) was used as a dual-role reagent to activate the oxime moiety and to donate a fluoride. The key intermediates, α-oximino-β-ketoesters, were prepared by highly efficient acid-assisted oximation of β-ketoesters. Then, the deconstruction of α-oximino-β-ketoesters by the fluorinative C–C bond cleavage was demonstrated to provide cyanoformates. In this event, the fluoride addition followed by the C–C bond cleavage selectively occurred in the ketones over esters. Due to simple and mild reaction conditions, variously functionalized cyanoformates were exemplified.
Design, synthesis, structure, and dehydrogenation reactivity of a water soluble o-iodoxybenzoic acid derivative bearing a trimethylammonium group
Cui, Li-Qian,Dong, Zhi-Lei,Liu, Kai,Zhang, Chi
supporting information; experimental part, p. 6488 - 6491 (2012/02/02)
5-Trimethylammonio-1, 3-dioxo-1, 3-dihydro-1λ5-benzo[d][1, 2]iodoxol-1-ol anion (AIBX 1a), an o-iodoxybenzoic acid (IBX) derivative having the trimethylammonium moiety on its phenyl ring, possesses very good solubility in water and distinct oxidative properties from IBX, which is demonstrated in the oxidation of various β-keto esters to the corresponding dehydrogenated products using water as cosolvent. The regeneration of AIBX 1a can be easily realized from the reaction mixture due to its good water solubility.2011 American Chemical Society.
Delineating origins of stereocontrol in asymmetric Pd-catalyzed α-hydroxylation of 1,3-ketoesters
Smith, Alexander M. R.,Rzepa, Henry S.,White, Andrew J. P.,Billen, Denis,Hii, King Kuok
supporting information; experimental part, p. 3085 - 3096 (2010/07/17)
Systematic studies of reaction conditions and subsequent optimization led to the identification of important parameters for stereoselectivity in the asymmetric α-hydroxylation reaction of 1,3-ketoesters. Enantioselectivities of up to 98% can be achieved for cyclic substrates and 88% for acyclic ketoesters. Subsequently, the combination of cyclic/acyclic ketoester, catalyst, and oxidant was found to have a profound effect on reaction rates and turnover-limiting steps. The stereochemistry of the reaction contradicts that observed for other similar electrophilic substitution reactions. This was rationalized by transition-state modeling, which revealed a number of cooperative weak interactions between oxidant, ligand, and counterion, together with C-H/π interactions that cumulatively account for the unusual stereoselectivity.
Enantioselective decarboxylation of β-keto esters with Pd/amino alcohol systems: Successive metal catalysis and organocatalysis
Kukula, Pavel,Matousek, Vaclav,Mallat, Tamas,Baiker, Alfons
supporting information; experimental part, p. 2699 - 2708 (2009/06/17)
The kinetics and mechanisms of one-pot cascade reactions of racemic β-keto esters to give chiral ketones in the presence of Pd/C-chiral amino alcohol catalyst systems were studied. Transformation of 2-methyl-l-tetralone-2- carboxylic acid benzyl ester (1) into 2-methyl-1-tetralone (4) in the presence of Pd/C and cinchona alkaloids or ephedrine was chosen as a model reaction. After the first reaction step, the Pd-catalysed dehenzylation of 1 to afford the corresponding β-keto acid (2), there are two possible reaction routes that may be catalysed by the chiral amino alcohol in solution or by Pd0 sites on the metal surface in co-operation with the adsorbed amino alcohol. The reaction intermediate 2 was synthesized, and the kinetics of decarboxylation were followed by NMR, UV and IR spectroscopy. The studies revealed that the role of Pd is to trigger the reaction series by deprotection of 1. The subsequent dominant reaction route from the racemic β-keto acid 2 to the chiral ketone 4 is catalysed by the chiral amino alcohol in the liquid phase. It is shown that kinetic resolution of the diastereomeric salt of rac-2 and the chiral amino alcohol plays a key role in the enantioselection. High enantioselectivity necessitates an amino alcohol/rac-2 ratio of at least 2. A high ratio favours the formation of 1:1 amino alcohol/acid diastereomeric complexes, and the second amino alcohol molecule may be responsible for the enantioselective protonation of 2 in the diastereomeric complex.
Mechanistic insights into the palladium-induced domino reaction leading to ketones from benzyl β-ketoesters: First characterization of the enol as an intermediate
Detalle, Jean-Francois,Riahi, Abdelkhalek,Steinmetz, Vincent,Henin, Francoise,Muzart, Jacques
, p. 6528 - 6532 (2007/10/03)
The monitoring by UV spectroscopy of the Pd-catalyzed hydrogenolysis in acetonitrile of 2-methyl-2-benzyloxycarbonyl-1-indanone and 2-methyl-2- benzyloxycarbonyl-1-tetralone showed the successive formation of corresponding β-ketoacids and enols to deliver finally the ketones. Some factors which influence the stability of the intermediates are determined. In contrast to the above benzyl β-ketoesters, the enol was not detected from benzyl (2-methylinden-3-yl) carbonate.
