Caronic acid, structure

Hydrolysis of cinenn I gives an optically active carboxylic acid (+) chrysanthemic acid Ozonolysis of (+) chrysanthemic acid followed by oxidation gives acetone and an optically active dicarboxyhc acid (—) caronic acid (C7H10O4) What is the struc ture of (—) caronic acid" Are the two carboxyl groups cis or trans to each other What does this information tell you about the structure of (+) chrysanthemic acid" ... 

Fujitani [6] separated the insecticidally active syrupy ester from pyrethrum flowers in 1909 and named the ester pyrethron. Yamamoto [7, 8] subjected the hydrolysis product of this pyrethron to ozone oxidation, and isolated Iram-caronic acid and aldehyde (1 and 2, respectively, Fig. 3). Although Yamamoto did not determine the structure of this acid, he presumed it to be pyrethron acid (Fig. 3). Eventually, the presence of a cyclopropane ring in the molecule of natural pyrethrins became clear for the first time in 1923. 

Because caronic acid is optically active, its carboxyl groups must be trans to each other. (The cis stereoisomer is an optically inactive meso form.) The structure of (+)-chrysanthemic acid must therefore be either the following or its mirror image. 

Caron, A., Brand, C., Bunel, C. and Vert, M. (1990) Blocky structure of copolymers obtained by Pd/C-catalyzed hydrogenolysis of benzyl protecting groups as shown by sequence-selective hydrolytic degradation in poly(j -malic acid) derivatives, Polymer, 31, 1797-802. 

Brand, C., Caron, A., Francillette, J., Guerin, P. and Vert, M. (1988). Poly ()5-malic acid) stereocopolymers structural characteristics and degradation in aqueous media, Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.), 29,600-1. 

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