Abstract
The geometrical configuration of αδ-dimethylsorbic acid, an important intermediate in our successful total synthesis of chrysanthemum-dicarboxylic acid, is confirmed to be trans by the ultra-violet and infra-red absorptions and also by the dissociation constant of αδ-dimethyl-Δα-hexenoic acid derived from the parent αδ-dimethylsorbic acid by semi-hydrogenation over a palladium catalyst. Thus, the trans-configuration of this acid, previously deduced on a theoretical basis, is free from any experimental defect, and thence, the trans-configuration of the side-chain double-bond of the naturally derived chrysanthemum-dicarboxylic acid follows from the method of synthesis from trans-αδ-dimethylsorbic acid. This method of assignment may, in general, be applicable to the α-alkyl substituted conjugated diene carboxylic acids.
