Ethyl a-acetyl-/3-

Polyphosphoric acid in cyclization of ethyl a-acetyl-/3-(2,3-dimethoxy-phenyl)propionate to 6,7-dimeth-oxy-3-methylindene-2-carboxyl-ate, 40, 43... 

Ethyl a-ACETYL-/3-(2,3-DiMETHOXY-phenyl)propionate, 31, 56 Ethyl a-acetyl-/3-(3,4-dimethoxyphenyl)-propionate, 31, 58... 

The method described is that of Hampton, Harris, and Hauser6 and is an improvement over the benzyne method, which gives poor yields.6,7 This /J-diketone has been prepared by Claisen condensation of ethyl phenylacetate with acetone,8 but the yield is poorer and the product has been shown by gas chromatography to be impure.6 The j8-diketone has also been prepared by the hydrolysis of 4-methoxy-5-phenyl-3-penten-2-one and by hydrolysis and decarboxylation of ethyl a-acetyl-/3-oxo-y-phenylbutyrate10 but these compounds are more difficult to obtain than the starting materials used in the present synthesis. 

Ethyl acetoacetate, 31, 1, 57 32, 76, 84 Ethyl a-acetyl-/3-(2,3-dimethoxy-phenyl)acrylate, 31, 5(5, 58 Ethyl a-acetyl-/S-(3,4-dimethoxy-phenyl)acrylate, 31, 58 Ethyl q -acetyl-/3-(2,3-dimethoxy-phenyl)propionate, 31, 56 Ethyl a-acetyl-/3-(3,4-dimethoxy-phenyl)propionate, 31, 58 Ethylamine, 2-chloro-N,N-di-... 

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%. ... 

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