Benzoylacetic esters

Benzotriazole, 20,16 Benzoylacetic ester, 23, 35 Benzoylation of acetoacetic ester by ethyl benzoate, 23, 35 Benzoyl chloride, 24, 14 purification of, 24, 15 Benzoyl Cyanide, 24,14, 16 Benzoyleormic acid, 24,16 Benzoyl-o-toluidines, conversion to indoles, 22, 95... 

The action of propylene bromide and eodium acetacetlc or benzoylacetic esters proceeds as would be expected and methyIcycloprop nc=2-benzoyl-2 acid and methylcyclopropane-2-acetyl-2-acid are the products. The latter on boiling with water loses carbon dioxide with ring cleavage and acetolsobutylalcohol result 1... 

The reaction of diketene with aryl isocyanates in an acid medium furnished derivatives of 50.180,181 It was also found that acetoacetic and benzoylacetic esters react with unsymmetrical dimethylurea to yield 50 and 51, respectively [Eq. (38)]. 

By comparison, the <5(OHO) of acetoacetic ester is to be found at 12.17 ppm and benzoylacetic ester at 12.83 ppm30). This class of /3-dicarbonyl derivative has the cis enol tautomer signals in the narrow range of 12-13 ppm, relatively insensitive to a and /3 and ester substituents. 

The acylation of simple /3-keto esters with acyl chlorides to form di-acylacetic esters proceeds readily however, the subsequent cleavage for removing the smaller acyl group is complicated in that the original keto ester may be regenerated. The optimum conditions for the conversion of benzoylacetoacetic ester to benzoylacetic ester with ammonium chloride and ammonium hydroxide have been studied. The over-all synthesis of this ester has been described (57%). An improved procedure for the ammonolysis of ethyl a-acetyl-/3-oxocaproate using gaseous ammonia has been described. By a similar process, a series of alicyclic /3-keto esters has been prepared in over-all yields of 20-40%. ... 

Reactions using highly acidic active methylene compounds (pAa = 9-13) comprise nearly all the early examples of imine condensation reactions, some of which date back to the turn of the century. Reviews by Layer and Harada have summarized many of these reactions and include examples using diethyl malonate, ethyl cyanoacetate, ethyl malonamide, acetoacetic acid, benzoylacetic esters and nitroalkanes. Conditions of these reactions vary they have been performed both in protic and aptotic solvents, neat, and with and without catalysts. Elevated temperatures are generally required. Reactions with malonates have useful applications for the synthesis of 3-amino acids. For example, hydrobenzamide (87), a trimeric form of the benzaldehyde-ammonia Schiff base, and malonic acid condense with concomitant decarboxylation to produce p-phenylalanine (88) in high yield (equation 14). This is one of the few examples of a Mannich reaction in which a primary Mannich base is produced in a direct manner but is apparently limited to aromatic imines. 

Heating 6-amino-l,3-dimethyluracil together with 2-chlorobenzaldehyde and a 4-substituted benzoylacetic ester in refluxing ethanol directly leads to the corresponding 5,8-dihydropyrido-[2,3-(7]pyrimidine.273 Similarly, other uracils react with aromatic aldehydes and various alkyl acetoacetates in propan-2-ol.235... 

Shriner and Schmidt161 have described the following similar procedure for preparation of benzoylacetic ester from benzoylacetoacetic ester by gentle warming with an aqueous solution of ammonia and ammonium chloride ... 

Benzotriazole, 20, 16 Benzoylacetanilide, 25, 7 Benzoylacetic ester, 23, 35 Benzoylation of acetoacetic ester by... 

Dilute sodium hydroxide was used as a condensing ent by J. G. Schmidt and the method was applied by Claisen and collaborators to the s3mthesis (Claisen reaction) of aromatic ketonic esters, e.g. benzylidene acetone and di-benzylidene acetone from benzaldehyde and acetone. An alternative method was the use of an aromatic aldehyde or ketone with acetoacetic ester in presence of hydrogen chloride. Benzoylacetic ester, CgHgCO CHe-COOCoHs, was obtained by condensing benzoic and acetic esters in presence of sodium ethoxide, and j8-diketones by condensing ketones and acid esters, e.g. acetyl-acetone CHaCO-CHaCOCHg."... 

Fig. 3 Asymmetric reduction of benzoylacetate esters and [l-keto esters...

Some (co-dialkylamino)alkyl benzoylacetate esters undergo remote hydrogen abstraction probably initiated by electron transfer to form 1,8, 1,9, or 1,10 biradicals and their azalactone cyclization products. Contrary to most other such reactions, a hydrogen gets transferred from an internal methylene next to nitrogen to produce aminolactones. 

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