Synthesis and properties of mono-, di- and trienoic fatty esters containing a 12,13 double bond
1983
Rakoff, H. | Emken, E.A.
Methyl trans-12-octadecenoate-9, 10-d2 was obtained from methyl threo-12, 13-dihydroxy-cis-9-octadecenoate by a sequence of reactions involving formation of an ethoxydioxolane, catalytic deuteration of the double bond, and conversion of the ethoxydioxolane group to an ethylenic bond. Methyl cis- and trans-12-octadecenoate-15, 15, 16, 16-d4 and methyl cis- and trans-12-octadecenoate-9, 10, 15, 15, 16, 16-d6 were obtained from the Wittig coupling of hexyl-3, 3, 4, 4-d4-triphenylphosphonium bromide with methyl 12-oxododecanoate and methyl 12-oxododecanoate-9, 10-d2, respectively. The four geometrically isomeric methyl 12, 15-octadecadienoates-9, 10-d2 were prepared by the Wittig reaction between cis- or trans-3-hexenyltriphenylphosphonium bromide and methyl 12-oxododecanoate-9,-10-d2 with butyl lithium in ethyl ether. The Wittig reaction between hexyl-3, 3, 4, 4-d4 -triphenylphosphonium bromide and methyl 12-oxo-cis- or trans-9-dodecenoate was used to prepare the four geometric isomers of methyl 9, 12-octadecadienoate-15, 15, 16, 16-d4, whereas the same reaction between eis- or trans-3-hexenyltriphenyl-phosphonium bromide and methyl 12-oxo-cis- or trans-9-dodecenoate afforded the eight geometrically isomeric methyl 9, 12, 15-octadecatrienoates. In each case, the stereochemistry of the double bond formed in the Wittig reaction was controlled by choice of reaction conditions. Pairs of isomers formed during each synthesis were separated by partial silver resin chromatography. Physical constants presented include13C nuclear magnetic resonance chemical shifts, melting points, equivalent chain lengths and percentage trans by infrared spectroscopy.
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