63921-06-2Relevant articles and documents
Evidence for Ketene Intermediates in the Reactions of 2-Oxobutanedioic Acid Diesters with Alcohols and Water
Emerson, David W.,Titus, Richard L.,Gonzalez, Rowena M.
, p. 3572 - 3576 (2007/10/02)
The reactions of diethyl ester (1a) and dimethyl ester (1b) of 3-methyl-2-oxobutanedioic acid with excess ethanol, methanol, or water in a sealed tube at approximately 125 deg C were studied.With methanol, 1a yielded mainly 3-methyl-2-oxobutanedioic acid 1-ethyl 4-methyl diester, 2a; with ethanol, 1b yielded mainly the 4-ethyl 1-methyl diester, 2b, while reaction of 1a with water yielded carbon dioxide, 2-oxobutanoic acid ethyl ester, 6, and 2-methyl-3-oxopropanoic acid ethyl ester, 7.These results suggested that the ketene intermediates 3-methyl-2,4-dioxo-3-butenoic acid ethyl or methyl ester, 4a and 4b, respectively, are implicated.The similarity of these reactions to those exhibited by ethyl acetoacetate, such as alkoxy group exchange, and formation of dehydroacetic acid, now thought to proceed by way of acetyl ketene, was demonstrated.
Synthesis of the (Z) and (E) Isomers of 1,2-Diaryl-3-methyl-4,5-dioxo-3-pyrrolidinecarboxylic Acid Esters. Structural Assignment by NMR and Mass Spectroscopy
Titus, Richard L.,Emerson, David W.,Gonzales, Rowena M.
, p. 1857 - 1860 (2007/10/02)
Reaction of N-benzylideneaniline, 1a, with 3-methyl-2-oxobutanedioic acid diethyl ester, 2a, produced isomeric 3-methyl-4,5-dioxo-1,2-diphenyl-3-pyrrolidinecarboxylic acid ethyl esters, 3a and 3b.The higher melting isomer, 3a, was shown to have (Z) configuration by nmr spectroscopy.The (Z) and (E) isomers of 3-methyl-4,5-dioxo-1,2-diphenyl-3-pyrrolidinecarboxylic acid methyl esters, 3c and 3d, were prepared from 1a and 3-methyl-2-oxobutanedioic acid dimethyl ester, 2b.The higher melting isomer, 3c, was shown to have the (Z) configuration.Similarly, N-benzylidene-p-toluidine, 1b, reacted with 2a to form (Z) and (E) isomers of 3-methyl-4,5-dioxo-1-(4-methylphenyl)-2-phenyl-3-pyrrolidinecarboxylic acid ethyl esters, 3e and 3f.Assignment o the 13C carbonyl carbon nmr chemical shift was made by preparing 2-methyl-3-oxobutanedioic-1-13C acid diethyl ester, 4, and from it the corresponding (Z) and (E) isomers of 3-methyl-4,5-dioxo-1,2-diphenyl-3-pyrrolidinecarboxylic 13C acid ester, 5a and 5b.The mass spectra of the (Z) isomers exhibit prominent ions corresponding to the masses of the Schiff bases used to make them, and ions corresponding to the loss of Ar-NCOCO from the parent ion.The (E) isomers 3b, 3d and 5b exhibit a prominent ion of mass 264; 3f gives mass 278, corresponding to the loss of the carboalkoxy group.
Synthesis of erythro-2-Hydroxy-3-methylbutane-1,4-dioic Acid
Bhat, K. S.,Dixit, K. N.,Rao, A. S.
, p. 509 - 512 (2007/10/02)
Reduction of ethyl 3-methyl-2-oxobutane-1,4-dioate (3) with sodium borohydride furnishes a 6:1 mixture of ethyl erythro-2-hydroxy-3-methylbutane-1,4-dioate (8) and ethyl threo-2-hydroxy-3-methylbutane-1,4-dioate (18).Hydrolysis of this mixture with aq. hydrochloric acid gives a mixture of acids from which pure erythro-2-hydroxy-3-methylbutane-1,4-dioic acid (4) has been isolated.The stereochemistry of 4 has been establishrd by PMR and by transforming it to the anhydride, erythro-dihydro-3-acetyloxy-4-methyl-2,5-furandione (26).
The Use of Microorganisms in Organic Synthesis. II. Microbiological Asymmetric Reduction of 2-Methyl-3-oxosuccinates
Akita, Hiroyuki,Furuichi, Akiya,Koshiji, Hiroko,Horikoshi, Koki,Oishi, Takeshi
, p. 4384 - 4390 (2007/10/02)
In order to synthesize four optically active methyl 2-methylmalates (10-13), microbiological asymmetric reduction of the corresponding dimethyl 2-methyl-3-oxosuccinate (9) was carried out.The β-keto diester 9 was found to be reduced by fermenting baker's yeast (Saccharomyces cerevisiae) and Candida albicans to afford a mixture of the (2R,3R)-isomer 10 and the (2S,3R)-isomer 11.Although the optical purity of 10 produced by Candida albicans was reasonably high (95percent e.e.), optical yields of other products were unexpectedly low.However, identification of the four possible isomers 14-17 was found to be easily carried out by means of nuclear magnetic resonance spectroscopy.Keywords - α-methyl-β-keto ester; methylmalate; asymmetric reduction; microbiological reduction; yeast; methyl 2-methylmalate
Specific Two-Step Decarboxylation of Copper(I,II) β-Keto Carboxylates. A Novel Type of Regulation of the Decarboxylation of β-Keto Acids
Tsuda, Tetsuo,Chujo, Yoshiki,Takahashi, Seiji,Saegusa, Takeo
, p. 4980 - 4987 (2007/10/02)
Copper(I,II) β-keto carboxylates undergo a specific two-step decarboxylation.For example, the decarboxylation of copper(I) 1-oxocyclohexane-2-carboxylate (1) evolves CO2 in a 50percent yield in dimethylformamide (DMF) at 70 deg C.No further CO2 evolution beyond this 50percent decarboxylation occurs at 70 deg C.At a higher temperature of 120 deg C., the remaining 50percent of the CO2 is released.This specific two-step decarboxylation of 1 results from the intermediate formation of a dicopper(I) salt of the enol of 1-oxocyclohexane-2-carboxylic acid (10) which is stable to decarboxylation at 70 deg C.Compound 10 is isolated from the reaction mixture after the 50percent decarboxylation.Decarboxylations of copper(I,II) benzoylacetates, copper(I) oxaloacetate, copper(II) 1-oxo-cyclohexane-2-carboxylate, and copper(II) chloride 1-oxocyclohexane-2-carboxylate also proceed stepwise in DMF.On the other hand, copper(I,II) benzoylcyclopropane-1-carboxylates without an enolizable α-hydrogen atom evolve CO2 in a usual one-step manner.The present specific two-step decarboxylation of copper(I,II) β-keto carboxylates provides a novel type of regulation of the decarboxylation of β-keto acids and also a method of generating copper(I,II) enolate.The bearing of the two-step decarboxylation of copper(I) β-keto carboxylates on both the Cu(I)-mediated carboxylation of ketones and organic synthesis is also described.
