Valence tautomers of dimethyl cycloocta-2,5,7-triene-1,4-dicarboxylate and an iron tricarbonyl complex therefrom

Article abstract of DOI:10.1016/0022-328X(87)80071-2

Carboxylation of cyclooctatrienyldilithium, Li2C8H8, gives predominantly tricyclo<5.1.0.0^2,4>oct-5-ene-3,8-dicarboxylic acid and trans,cis,cis,trans-deca-2,4,6,8-tetraene-1,10-dioic acid; in addition, a small quantity of cycloocta-2,5,7-triene-trans-1,4-dicarboxylic acid has been identified as its dimethyl ester.The tricyclooctene diester is in equilibrium with a small amount of the isomeric cis-disubstituted cycloocta-2,5,7-triene in solution, and heating such a solution results in formation of a dimer.Reaction of the tricyclooctene diester with iron pentacarbonyl produces exo(2-5)η-<3,8x-dicarbomethoxybicyclo<4.2.0>octa-2,4-diene> tricarbonyliron.