Chemical synthesis and spectroscopic characteristics of C18 1,2-disubstituted cyclopentyl fatty acid methyl esters

The chemical synthesis of methyl 9-(2′-n-butylcyclopentyl)nonanoate and methyl 10-(2′-n-propylcyclopentyl)-decanoate was performed using a Wittig reaction between 2-alkylcyclopentanones and the corresponding ω-carbomethoxyalkyl triphenylphosphonium bromides. The intermediate alkylcyclopentylidene alkanoate esters were isolated from the reaction mixture, characterized by spectrometric methods, and then catalytically hydrogenated to the desired cyclopentyl esters. Gas chromatographymass spectrometry (GC-MS) showed that the final products contained a mixture oftrans- andcis-ring isomers with small amounts of other cyclic by-products. The GC-retention features, the mass fragmentation pattern, and the spectroscopic characteristics of both the final and the unsaturated intermediate products are discussed.