ABSTRACT
Kanetsuna and Nonaka [70] examined in detail the stereochemistry of final cyclic products (XI) derived by hydrolysis from initially formed cross-coupling products (X) of crotonic acid derivatives with dissymetrical carbonyl compounds as in Eq. (9). The cistrans ratio of XI varied in a wide range from 2.2 to 0.22 depending on the molecular structure of the starting compounds and electrolytic conditions. Stereochemistry around the C-C bond formed by the coupling reaction was discussed in this case and in the coupling of 1-cyclohexenecarboxylic acid derivatives with a symmetrical ketone (acetone). The stereochemistry of the C-C single bond to the corresponding olefinic double bond was examined [71 ]. In the latter case, the cis-trans ratio of the products also varied, but the less stable cis products were always predominant. This results can be helpful for discussing stereocontrol in this reaction. In fact, Kanetsuna and Nonaka [71] discussed the stereochemical course based on these results.
