Synthesis and properties of a novel 1-pyrroline fatty ester derivative from methyl isoricinoleate

Reaction of methyl isoricinoleate [(Z)-methyl 9-hydroxyoctadec-12-enoate] with toluene-p-sulphonyl chloride gave a mixture of (Z)-methyl 9-chlorooctadec-12-enoate 2 and (Z)-methyl 9-tosyloxyoctadec-12-enoate 3, and with methane sulphonyl chloride the corresponding mesyloxy derivative 4. Treatment of compounds 2–4 with NaN3 in N,N-dimethylformamide at 50 °C gave (Z)methyl 9-azidooctadec-9-enoate 5, while at 80 °C methyl 8-(5-hexyl-2-pyrrolin-1-yl)octanoate 6 was obtained. The 1-pyrroline ring was characterized by IR,1H and 13C NMR spectroscopy, while the ring cleavage products (methyl 9-acetamido-12-oxooctadecanoate 7 and methyl 9-benzamido-12-oxooctadecanoate 8) were characterized by GC–MS. Reduction of the CN bond in compound 6 with NaBH4 gave a mixture of E- and Z-isomers of the corresponding disubstituted pyrrolidine fatty esters 9a and 9b.