Y-Diketo acids

Note It is important to observe that the ester of a,y-diketo acid chemoselectively affords only y-oxime since the a-keto group is completely enolized (Scheme 7.7). It is also worth mentioning that inversion of the reactivity of two carbonyl groups is possible on lactonization. Within stable enol-lactone, the a-carbonyl group then reacts. 

The second group of syntheses effected via ABD derivatives linked by a Cg—Ci4 bond was first proposed, also by Robinson, in 1938 [374]. In these syntheses, ring C is formed by the cyclization of acids of the type of (270) (Scheme 26) obtained, in their turn, from the y-diketo acids (268) with an aromatic substituent comprising rings A and B and a side chain comprising atoms Cij—C17. This method leads directly only to equilenin derivatives, but the reduction of these has enabled some derivatives of estrone to be obtained. 

Carboxyalkyl-Y-but5U olactone has also been S5mthesized by combining pure enz5mies and whole microbial cells in the same process. Thus, the corresponding 2-hydroxy esters and lactones were obtained from 2-oxoglutaric acid [219]. Low ee values, however, were obtained for the reduction of a,y-diketo esters and keto a,y-diesters [220-224]. 

Hao, Z., Iqbal, A. and Herren, F. (1999c). l,4-Diketo-3,6-bis-4-chloro-phenyl-pyrrolopyrrole in /3 and y modification, prepd. by acid hydrolysis of soluble carbamate. Derivation and preparation by cooling. Ciba-Geigy Ltd. EP 690059 B1. [271 ] Harano, Y. and Oota, K. (1978). Measurement of crystallization of potassium bro-mate from its quiescent aqueous solution by differential scanning calorimeter. Homogeneous nucleation rate. /. Chem. Eng. J., 11, 159-61. [70]... 

By using active peptide esters with high molecular ester components, inter-molecular aminolysis can be suppressed. — E Glycyl glycine cross-linked poly-(4-hydroxy-3-nitrostyrene) ester hydrobromide suspended in dimethylformamide, neutralized with triethylamine, allowed to stand 12 hrs. at room temp., and the resulting poly-4-hydroxy-3-nitrostyrene removed by filtration diketo-piperazine. Y 75%. F. e. and ester components s. M. Fridkin, A. Patchornik, and E. Katchalski, Am. Soc. 87, 4646 (1965) peptides s. T. Wieland and G. Birr, Ang. Gh. 78, 303 (1966) with active a-aminocarboxylic acid polyphenolesters s. M. Fridkin, A. Patchornik, and E. Katchalski, Am. Soc, 88, 3164 (1966). 

Diketo- from y -keto-carboxylic acid esters... 

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