Rhodium‐catalysed cyclisation by addition of unsaturated 1,4‐dicarbonyl compounds to oleic acid methyl ester

Abstract

The Rh‐catalysis allows the one‐step synthesis of Diels–Alder‐like cycloadducts from mono‐unsaturated fatty acid and 1,4‐dicarbonyl components. In this article we report on the addition of maleic acid‐, fumaric acid‐ and acetylene dicarboxylic acid dimethyl ester to oleic acid methyl ester. In previous studies, Rh(OAc)2 showed the highest selectivity of the investigated catalysts towards the 3,6‐disubstituted‐1,2,3,6‐tetrahydro‐phthalic acid derivatives (THPA) for the addition of maleic anhydride to oleic acid. Thus, it was also used in this study. The relative configurations of the final products were identified by comparison with the Diels–Alder products, resulting from conjugated linoleic acid methylester (CLAMe) and the mentioned 1,4‐dicarbonyl compounds.Practical applications: The Rh‐catalysis is an appropriate method to synthesise Diels–Alder‐like cycloadducts from mono‐unsaturated fatty acids derivatives and 1,4‐dicarbonyl compounds in a one‐step process. The resulting products are considered to be used as detergents, corrosion inhibitors, plasticiser or new monomeric building blocks, e.g. for polycondensation processes. The obtained polyesters can be used for several applications, e.g. for coatings or adhesives, and lead to new products with promising properties.Diels–Alder‐like cycloadducts can be obtained in a one‐pot reaction from mono‐unsaturated fatty acids and 1,4‐dicarbonyl compounds using Rh‐catalysts. In contrast to common Diels–Alder reactions, a conjugated diene is not mandatory as educt, but will be generated in situ from the mono‐unsaturated fatty acid compound. The configurations of the resulting cyclocadducts are determined by NMR‐measurements.