Oxalate, diethyl, reaction with

However, Claisen found in 1889 that a second molecule of ethyl acetate (with CH3 hydrogen atoms activated by COOEt) was not the only possible partner for a condensation reaction It could be replaced by a variety of other molecules, such as aldehydes and ketones (activation by CO group) and methyl cyanide and its derivatives (activation by CN group). Many condensation reactions of esters with nitriles were discovered, e.g. diethyl oxalate reacts with methyl cyanide in the presence of sodium ethoxide (Fleischhauer, 189320) ... 

One route to o-nitrobenzyl ketones is by acylation of carbon nucleophiles by o-nitrophenylacetyl chloride. This reaction has been applied to such nucleophiles as diethyl malonatc[l], methyl acetoacetate[2], Meldrum s acid[3] and enamines[4]. The procedure given below for ethyl indole-2-acetate is a good example of this methodology. Acylation of u-nitrobenzyl anions, as illustrated by the reaction with diethyl oxalate in the classic Reissert procedure for preparing indolc-2-carboxylate esters[5], is another route to o-nitrobenzyl ketones. The o-nitrophenyl enamines generated in the first step of the Leimgruber-Batcho synthesis (see Section 2.1) are also potential substrates for C-acylation[6,7], Deformylation and reduction leads to 2-sub-stituted indoles. 

Primary synthesis of arylazopyrimidines is used (52JCS3448). It is exemplified in the condensation of phenylazomalondiamidine with diethyl oxalate to give the azopyrimidine (833) (66JCS(C)226). Finally, 5-phenylazopyrimidine may be made by the condensation of pyrimidin-5-amine with nitrosobenzene (5UCS1565) but the reaction seems to have been overlooked for many years. 

Derivatives (410) of a canthinone may be prepared readily from the dilithio derivative of the appropriate j8-carboline (409) by reaction with diethyl oxalate. Reversal of this condensation accounts for... 

Another acylated ampicillin derivative with expanded antimicrobial spectrum is piperacil1 in (19). Its synthesis begins with 1-ethyl-2,3-diketopiperazine (j7, which itself is made from ]i-ethylethylenediamine and diethyl oxalate), which is activated by sequential reaction with trimethylchlorosilane and then trichloromethyl chioroformate to give This last... 

To this acid was then added 1 g of 4-ethyl-2,3-dioxo-1-piperazinocarbonyl chloride (from the reaction of N-ethylethylenediamine and diethyl oxalate to give 2,3-dioxo-4-ethyl-piperazine which Is then reacted with phosgene) and the resulting mixture was reacted at 15°C to 20°C for 2 hours. After the reaction, a deposited triethylamine hydrochloride was separated by filtration, and the filtrate was incorporated with 0.4 g of n-butanol to deposit crystals. The deposited crystals were collected by filtration to obtain 1.25 g of white crystals of 6-[ D(—l-Ct-(4-ethyl-2,3-dioxo-1 -piperazinocarbonylaminolphenylacetamido] penicillanic acid. Into a solution of these crystals in 30 ml of tetrahydrofuran was dropped a solution of 0.38 g of a sodium salt of 2-ethyl-hexanoic acid in 10 ml of tetrahydrofuran, upon which white crystals were deposited. The deposited crystals were collected by filtration, sufficiently washed with tetrahydrofuran and then dried to obtain 1.25 g of sodium salt of 6-[D(—)-a-(4-ethyl-2,3-di-0X0-1-piperazinocarbonylaminolphenylacetamido] penicillanic acid, melting point 183°C to 185°C (decomposition), yield 90%. 

Diethyl oxalate, (CCqEt, often gives high yields in mixed Claisen reactions. What product would you expect to obtain from a mixed Claisen reaction of ethyl acetate with diethyl oxalate ... 

The reaction of cyclooctanone with diethyl oxalate, followed by decarbonylation of the resulting glyoxylate, has been reported to yield 32% of 2-carbethoxycyclooctanone.2 The reaction of cyclooctanone with sodium amide in ether, followed by the... 

Ethyl o-nitrophenylpyruvate and o-nitrophenylpyruvic acid 14-21 have been prepared by condensation of o-nitrotoluene with diethyl oxalate in the presence of potassium ethoxide,4 14 sodium ethoxide,16-20 or sodium methoxide.21 Sodium ethoxide is less reactive, however, and cannot be substituted successfully for potassium ethoxide in the present procedure, as it gives a very poor yield and poor quality of precipitated sodium salt. With sodium ethoxide the reaction does not appear to go to completion even under the conditions of refluxing ethanol usually employed,16-21 which are considerably more severe than the room temperature conditions employed with potassium ethoxide in the present procedure. o-Nitrophenylpyruvic add has also been prepared by hydrochloric acid hydrolysis of o-nitro-a-acetamino-dnnamic azlactone.4... 

Reaction of the hydrazinoquinoline derivative 148 with ethyl bromoacetate or diethyl oxalate gave the cyclized product 149 in high yield upon microwave irradiation (Equation 22) <1998IJB174>. 

A pyranothiazolotriazine 240 was synthesized in good yield by the reaction of thiazolohydrazine derivative 239 with diethyl oxalate (Equation 29) <1999ZNB1589>. 

Parabanic acid can be prepared by the condensation of urea with diethyl oxalate in an ethanolic solution of sodium ethoxide,2 by reaction of urea with an ethereal solution of oxalyl chloride,3 by oxidizing uric acid with an acid solution of perhydrol,4 or by the action of hot, concentrated nitric acid on uric acid.5 The present method gives better yields than the previously reported methods and is better adapted to larger-scale preparations. 

The 2,3-dioxo-6-thioxo-2,3,5,6-tetrahydro-l/7-imidazo[l,2-A]pyrazole 393 and 5,6-dioxo-2,3-dihydro-l//-imidazo[l,2- ]-imidazole 395 were synthesized by condensation of the respective 5-amino-3-thioxo-2,3-dihydro-pyrazole 392 and 2-aminoimidazoline 394 compounds with either oxalyl dichloride or diethyl oxalate in moderate to poor yields (Equations 178 and 179) <1995JPR472, 2002EJM845>. These cyclizations can suffer from various side reactions such as expulsion of CO, polymerization, or formation of open-chain products. To solve these problems, reagents such as oxalic acid bis-imidoyl- and bis-hydrazoylchlorides 397 and 400 as well as 2,3-dichloroquinoxalines 403... 

The reactivity of amino functions on diazotization and condensation with dimethylformamide dimethyl acetal has been discussed in CHEC-II <1996CHEC-II(7)431>. The diamine 220 is readily converted into a variety of tricyclic pyrazolo[3,4-r/ pyrimidines under a variety of conditions <2004T5093>. Thus with chloroacetyl chloride the chlor-oacetyl derivative 221 was formed. This could not be further cyclized into 222. Refluxing 220 with diethyl oxalate afforded 223 while 224 was formed when the reaction was conducted at 40 °C. Treatment of 224 with POCI3 afforded 223. Reacting 220 with carbon disulfide afforded 225 (Scheme 14) <2004T5093>. 

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