Diethyl oxalacetate

There are at least eight syntheses of orotic acid in the literature. The most practical in the laboratory is that involving the condensation of diethyl oxalacetate (972) with S-methylthiourea to give 2-methylthio-6-oxo-l,6-dihydropyrimidine-4-carboxylic acid (973) which undergoes either direct acidic hydrolysis or a less smelly oxidative hydrolysis, via the unisolated sulfone (974), to afford orotic acid (971) (B-68MI21303). 

Cyclization of 1-ureidopyrroles 88 with a base gave (79JHC833) pyr-rolo[2,l-/][I,2,4]triazines 89. Pyrolysis of 89 (R2 = COOH) afforded 90. Compounds 88 were prepared by treating chloroacetone semicarbazone 85 with the sodium salts of diethyl oxalacetate or oxalylacetophenone 86 to give semicarbazones 87, which were converted to 88 by the action of hydrochloric acid (Scheme 22). 

Metal amalgams may be used for reduction of the keto groups in keto esters provided the medium does not cause hydrolysis of the ester. Because of that aluminum amalgam in ether is preferable to sodium amalgam in aqueous solutions. Diethyl oxalacetate was reduced to diethyl malate by sodium amalgam in 50% yield and with aluminum amalgam in 80% yield [148], Stereospecific reduction of a- and fi-keto esters to optically pure hydroxy esters was achieved by biochemical reduction in moderate to good yields. Saccharomyces cerevisiae converted methyl 2-keto-2-phenylacetate to methyl... 

A series of oxygenated pyrrole derivatives have been obtained in moderate yields in an approach involving sodium diethyl oxalacetate, amines, and aromatic aldehydes, as illustrated by the preparation of the product 531 (Equation 144) <2006T6018>. 

Diethyl methyloxalacetate (106J, R = Me) adds to tetrahydropyridine and forms a new pyrroledione ring, but diethyl oxalacetate gives a product which is shown to be the enol form of the corresponding dione [2744]. The 1,2-double bond of 3A/-indoles undergoes a cycloaddition on treatment at ambient temperature with either diethyl oxalacetate or oxalopropionate. When R = H, the product may exist as its 2-hydroxy tautomer [3394]. Successive N- and... 

The 5,6,7,8-tetrahydro-7,7-dimethyl-2,5-dioxo-2H-l-benzopyran-4-carboxylic ester 435 was prepared from 1 and sodium diethyl oxalacetate in trifluoroacetic acid. Hydrolysis of the ester group in 435 gave 436 whose decarboxylation afforded the 7,8-dihydrobenzopyran 437 (72JOC1337). 

Ethyl Oxalacetate. Oxobutanedioie add diethyl ester diethyl oxalacetate oxaloacetic ester. C Hl2Os mol wt 188.18. C 51,06%, H 6,43%. O 42.51%. C OOCCH CO-COOCjHj. Obtained by the action of sodium on a mixture of ethyl oxalate and ethyl acetate. 

AI3-04820 Butanedioic acid, oxo-, diethyl ester, ion(l-), sodium Diethyl oxalacetate sodium salt Diethyl oxaloacetate, monosodium salt Diethyl oxobutanedloate ion(l-) sodium Diethyl sodiooxalacetate Diethyl sodium oxalacetate EINECS 255-122-9 NSC 126906 Oxalacetic acid diethyl ester sodium salt Sodium diethyl oxaloacetate Sodium diethyl oxobutanedloate. 

Another interesting approach to the less readily accessible diethyl ( S)-malate (3) is enan-tioselective bioreduction of sodium diethyl oxalacetate (4) with baker s yeast Saccharomyces cerevisiae). Under fermenting conditions, 3 is produced in high yield with >98% ee [10]. 

It is of interest that diethyl oxalacetate (Scheme 4.6.), that can be considered both as an alpha- and a fteta-keto ester, caimot be hydrogenated on the RNi-TA catalyst. This demonstrated that small changes in the groups around the carbonyl group may result in difficulties in asymmetric hydrogenation (Tanabe et al. ). 

The synthesis of barbituric acid can be best accomplished from diethyl malonate and urea, with an alkaline catalyst, such as sodium ethoxide in ethanol [113]. Barbituric acid-2- C has been prepared from urea- C and diethyl malonate [114]. The 4- C and 5- C compounds have been obtained by the pyrolysis of diethyl oxalacetate-3- C, which produced an equimolar mixture of 4- and 5- C barbituric acid after a rather lengthy procedure [115]. 

Diethyl oxalacetate is reduced in acidic media in protonated keto and protonated enol form, at pH > 6 in the unprotonated form. The carbanion-enolate present at pH > 9 is not reducible. 

A soln. of 4-amino-3-hydroxy-5-methylacetophenone and the equivalent amount of diethyl oxalacetate refluxed 1 hr. ethyl 5-methyl-7-acetylbenz-l,4-oxazin-2-on-3-ylacetate. Y ca. 90%.—Because these benz-l,4-oxazin-2-ones crystallize well and can be cleaved by alkali, they are suitable for the separation of aminophenols and the identification of the o-isomers. Even isomeric o-aminophenols can be separated due to different reaction rates. F. e. s. A. Butenandt, E. Biekert, et al., B. 92, 2172 (1959). Condensed l,4-oxazin-2-ones may also be used for the identification of a-ketocarboxylic acid esters. E. s. B.94, 1664 (1961). 

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