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Beta-ketoesters

Carbon is alkylated ia the form of enolates or as carbanions. The enolates are ambident ia activity and can react at an oxygen or a carbon. For example, refluxing equimolar amounts of dimethyl sulfate and ethyl acetoacetate with potassium carbonate gives a 36% yield of the 0-methylation product, ie, ethyl 3-methoxy-2-butenoate, and 30% of the C-methylation product, ie, ethyl 2-methyl-3-oxobutanoate (26). Generally, only one alkyl group of the sulfate reacts with beta-diketones, beta-ketoesters, or malonates (27). Factors affecting the 0 C alkylation ratio have been extensively studied (28). Reaction ia the presence of soHd Al O results mosdy ia C-alkylation of ethyl acetoacetate (29). [Pg.199]

The Pechmaim reaction has found extensive appHcations for the synthesis of numerous coumarin derivatives (39). Coumarin derivatives substituted in the pyrone ring can be obtained by condensing phenol with beta-ketoesters. For example, 4-methylcoumarin (3) is obtained with ethyl acetoacetate... [Pg.320]

Coumarin can also be formed by the reaction of phenol with diketene (40). Similarly, diphenols can react with hydroxycarboxyUc acids or beta-ketoesters to give hydroxycoumaria derivatives. The reaction of resorciaol with malic acid produces umbeUiferone (7-hydroxycoumaria) and its reaction with ethyl acetoacetate gives beta-methylumbeUiferone (7-hydroxy-4-methylcoumaria). [Pg.321]

One such compound, bropirimine (112), is described as an agent which has both antineo-plastic and antiviral activity. The first step in the preparation involves formation of the dianion 108 from the half ester of malonic acid by treatment with butyllithium. Acylation of the anion with benzoyl chloride proceeds at the more nucleophilic carbon anion to give 109. This tricarbonyl compound decarboxylates on acidification to give the beta ketoester 110. Condensation with guanidine leads to the pyrimidone 111. Bromination with N-bromosuccinimide gives bropirimine (112) [24]. [Pg.117]

Three potential routes from 14 to 2, shown in Scheme 2.6, were identified and evaluated. Option A was the original plan of preparation. Hydroboration of the carbon-carbon double bond in 14 followed by oxidation provided primary alcohol 19 (P=H). Beta-ketoester 19 was converted to the corresponding diazo compound... [Pg.49]

Zhu, D., Mukherjee, C., Rozzell, J.D. et al. (2006) A recombinant ketoreductase tool-box. Assessing the substrate selectivity and stereoselectivity toward the reduction of beta-ketoesters. Tetrahedron, 62 (5), 901-905. [Pg.165]

Habib-Zahmani H, Viala J, Hacini S, Rodriguez J (2007) Synthesis of functionalized spiroheterocycles by sequential multicomponent reaction/metal-catalyzed carbocylizations from simple beta-ketoesters and amides. Synlett 1037-1042... [Pg.278]

The second arm of the scheme involves first a reaction of the (3-beta ketoester (7-1) with nitrous acid. The first product from nitrosation on the activated carbon spontaneously rearranges to afford oxime (7-2). Treatment with acetyl chloride then affords the (9-acylated oxime (7-3). Condensation of that compound with the imino ether from propionitrile leads to the formation of the imidazole (7-4). [Pg.387]

Habermas KL, Denmark SE, Jones TK (1994) Qrg React 45 1-158 Hagiwara E, Fujii A, Sodeoka M (1998) J Am Chem Soc 120 2474 Hamashima Y, Sasamoto N, Hotta D, Somei H, Umebayashi N, Sodeoka M (2005) Catalytic asymmetric addition of beta-ketoesters to various imines by using chiral palladium complexes. Angew Chem Int Ed Engl 44 1525-1529... [Pg.247]

A library of 500 bipyridines was synthesized using a solid state combinatorial approach using five beta-ketoesters, 10 aldehydes, and 10 enamines through sequential Knoevenagel/Hantzsch condensation reactions.56... [Pg.11]

Coman, S., Bendic, C., Hillebrand, M., Angulescu, E., Parvulescu, V.I., Petride, A (1998) Diastereoselective hydrogenation of cyclic beta-ketoesters over modified Ru-Zeolite catalysts. Chemical Industries Series (Catalysis of Organic Reactions, Herkes F.E., ed.) 75,169-181. [Pg.257]

The Knorr Pyrrole Synthesis. In this process, the starting materials are an alpha-amino ketone, or less commonly an alpha-amino aldehyde, and a beta-ketoester. In the latter, the protons on the alpha carbon are activated both by the keto and the ester carbonyls and are especially easily removed. The Knorr process starts with the condensation of the amino group with the keto group in the usual way to tie the two molecules together as in 4.29 of the example shown in Scheme 4.31. This species then undergoes intramolecular aldol-type condensation to form a reduced pyrrole derivative 4.30. [Pg.75]

Two classic furan syntheses were described in Chapter 4 an adaptation of the Paal-Knorr method (section 4.2.1) and the Feist-Benary synthesis (section 4.2.3), which starts with an alpha-haloketone and a beta-ketoester. Other ring-closing processes have been devised and are outlined elsewhere. It is of practical current importance to start syntheses with the readily available furfural (furan-2-carbaldehyde) or fiiran itself. The reason for this is that large-scale commercial syntheses of these compounds have been developed, and thus they are readily available and inexpensive. [Pg.225]

The Hantzsch synthesis, which was developed in 1882, is perhaps the best known of several ways to construct the pyridine ring. The original synthesis involved the three-component reaction mixture of a beta-ketoester, ammonia, and an aldehyde. The product is a dihydropyridine, which is easily oxidized to a pyridine. An example is given in Scheme 9.45. Two intermediate compounds have been detected in... [Pg.246]

A valuable synthesis of 4-alkylpyrimidines consists of the use of beta-ketoesters in reactions with the urea derivatives (Scheme 9.65). [Pg.260]

The number of atoms intervening between the central atoms of the two functional groups is given as a prefix to the number of the complex functional group. For example, an alpha keto ester is numbered 0.40, a beta ketoester is numbered 1.40, a gamma ketoester 2.40 etc. [Pg.143]

Chelating dicarbene palladium(II) complexes have been found to catalyze the Nazarov cyclization of divinyl-beta-ketoesters to the corresponding cyclopentenones (Fig. 29). The reactivity of the complexes was generally... [Pg.250]

A. Rioz-Martinez, A. Cuetos, C. Rodriguez, G. de Gonzalo, 1. Lavandera, M.W. Fraaije, V. Gotor, Dynamic kinetic resolution of alpha-substituted beta-ketoesters catalyzed by Baeyer-Villiger monooxygenases access to enantiopure alpha-hydroxy esters, Angew. Chem.-Int. Ed. 50 (2011) 8387-8390. [Pg.282]

Trost BM, Bream RN, Xu J. Asymmetric allylic alkylation of cyclic vinylogous esters and thioesters by Pd-catalyzed decarboxylation of enol carbonate and beta-ketoester substrates. Angew. Chem. Int. Ed. 2006 45 3109-3112. [Pg.212]

Hamashima Y, Yagi K, Takano H, Tamas L, Sodeoka M. An efficient enantioselective fluorination of various beta-ketoesters catalyzed chiral palladium complexes. J. Am. Chem. Soc. 2002 124 14530. [Pg.1374]


See other pages where Beta-ketoesters is mentioned: [Pg.1465]    [Pg.46]    [Pg.291]    [Pg.313]    [Pg.71]    [Pg.181]   
See also in sourсe #XX -- [ Pg.106 , Pg.119 , Pg.120 ]

See also in sourсe #XX -- [ Pg.1042 , Pg.1049 ]




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