No abstract

Reaction of 1‐mesyloxynonane with methyl 8‐aminooctanoate gives methyl 9‐azastearate (I, 20%); treatment of methyl 9(10),10(9)‐azidohydroxyoctadecanoate and methyl 10‐azido‐12‐hydroxyoctadecanoate with triphenylphosphine furnishes the corresponding aziridine derivative (II, 75%) and two geometric azetidine isomers (IIIa and IIIb, 37%), respectively. The aza function in compound I, the aziridine nucleus in compound II and the azetidine system in compounds IIIa, IIIb were characterized by1H nuclear magnetic resonance (NMR) and13C NMR spectral analysis. The infrared spectral analyses of compounds (I), (II) and (IIIa,IIIb) showed characteristic absorption bands at 3200–3300 cm−1 for the N‐H stretching vibration.

A novel 1-pyrroline fatty acid ester isomer (viz. 8-5-hexyl-1-pyrrolin-2-yl) octanoate) has been synthesized from methyl ricinoleate by two routes with an overall yield of 42 and 30%, respectively. Most of the reactions are carried out under concomitant ultrasonic irradiation (20 KHz, ca. 53 watts/cm2). Under such a reaction condition, the reaction time is considerably shortened, and product yields are high. Dehydrobromination under concomitant ultrasonic irradiation of methyl 9, 10-dibromo-12-hydroxyoctadecanoate with KOH in EtOH furnishes methyl 12-hydroxy-9-octadecynoate (66%) within 15 min. Hydration of the latter under ultrasound with mercury(II)acetate in aqueous tetrahydrofuran yields exclusively methyl 12-hydroxy-9-oxo-octadecanoate (95%) in 30 min. The hydroxy group in the latter compound is transformed to the azido function via the mesylate, and treatment of the azido-oxo intermediate (methyl 12-azido-9-oxooctadecanoate) with Ph3P under ultrasonic irradiation furnishes the requisite 1-pyrroline fatty acid ester (77%). The same azido-oxo intermediate has also been obtained by the oxidation of methyl 12-azido-9-cis-octadecenoate using benzoquinone and a catalytic amount of Pd(II)chloride in aqueous tetrahydrofuran under concomitant ultrasonic irradiation (90 min) to give the product in 45% yield. The latter reaction does not take place even under prolonged silent stirring of the reaction mixture.

C18 furanoid triacylglycerol [glycerol tri-(9,12-epoxy-9,11-octadecadienoate)] was prepared by chemical transformation of triricinolein isolated from castor oil. The procedure involved oxidation, epoxidation and cyclization of the epoxy-keto intermediate with sodium azide and ammonium chloride in aqueous ethanol. The furanoid triacylglycerol was also obtained by esterification of C18 furanoid fatty acid with glycerol using Novozyme 435 (Novo Nordisk A.S., Bagsvaerd, Denmark) as biocatalyst. When Lipozyme (Novo Nordisk A.S.) was used, a mixture of the furanoid 1(3)-rac-monoacylglycerol and 1,3-diacylglycerol was obtained. In order to obtain the C18 furanoid 1,2(2,3)-diacylglycerol, selective hydrolysis of the furanoid triacylglycerol was achieved using porcine pancreatic lipase in tris(hydroxymethyl) methylamine buffer. Interesterification of triolein with methyl C18 furanoid ester in the presence of Lipozyme showed maximum incorporation of 34% of furanoid fatty acid. Extension of the interesterification to vegetable oils (olive, peanut, sunflower, corn and palm oil) allowed a maximum of 24% furanoid acid incorporation to be achieved.