Process for preparation of hexadecyl cis-9-tetradecenoate and hexadecyl cis-10-tetradecenoate

摘要

Hexadecyl cis-9-tetradecenoate commonly known as Cetyl myristoleate (CMO) is being used for the treatment of osteoarthritis and other joint inflammatory diseases, cis-9-Tetradecenoic acid (cis-9-myristoleic acid) is the main precursor for the preparation of CMO. As there are limited natural plant sources for cis-9-tetradecenoic acid, the present invention aimed at the synthesis of cis-9-tetradecenoic acid methyl ester from oleic acid methyl ester. As oleic acid is not available in pure form, this has to be isolated from oleic acid-rich oils like olive oil. cis-10-Tetradecenoic acid methyl ester, an isomer of cis-9-tetradecenoic acid was also prepared from undecenoic acid methyl ester, a derivative of castor oil. Undecenoic acid is easily available commercially in pure form. Hexadecyl cis-9-tetradecenoate and hexadecyl c/s-10-tetradecenoate were prepared by enzymatic transesterification of cis-9-tetradecenoic acid methyl ester and cis-10-tetradecenoic acid methyl ester with 1-hexadecanol (cetyl alcohol) respectively. Both the isomers of cetyl myristoleate were evaluated for anti arthritis, blocking inflammation and reduction of adjuvant-induced arthritis in rats.

主权项

1. A process for the preparation of two isomers of cetyl myristoleate namely hexadecyl cis-9-tetradecenoate and hexadecyl cis-10-tetradecenoate having general formula 1,comprising the steps of:
a. cooling of an ester selected from the group consisting of oleic acid methyl ester and methyl undecenoate in the presence of an organic solvent at temperature ranges between −70 to −78° C.; b. ozonolysis of cooled ester by bubbling of ozone for a period ranging between 60-90 min; c. quenching the reaction with dimethyl sulphide (DMS) followed by stirring for a period ranging between 6-8 hr at temperature ranging between 25-35° C.; d. evaporating the organic solvent and DMS from the reaction mixture as obtained in step (c) under vacuum to get a crude solid containing 1-al-methyl nonoate or 1-al-methyl deaconate depending upon the ester used in step (a); e. dissolving crude solid containing 1-al-methyl nonoate or 1-al-methyl deaconate as obtained in step (d) in dry THF (tetra hydro furan); f. simultaneously, dissolving triphenyl phosphine salt selected from the group consisting of n-pentyl-triphenyl phosphonium salt and n-butyl-triphenyl phosphonium salt in dry THF and cooled to a temperature ranging between 0-5° C. and followed by addition of n-butyl lithium; g. stirring the reaction mixture as obtained in step (f) for a period ranging between 30-60 min to obtain an orange solution; h. adding solution of crude solid in dry THF as obtained in step (e) into the solution of triphenyl phosphine salt in dry THF as obtained in step (f) followed by refluxing for a period of 0.3-8 hrs; i. removing THF from the reaction mixture as obtained in step (h) under reduced pressure to get residue; j. adding water in the residue as obtained in step (i) and followed by extraction with ether; k. removing ether under vacuum to get the residue followed by carrying, out purification using column chromatography using hexane and ethyl acetate (98:2) as eluent to get cis-9-myristoleate and cis-10-myristoleate depending upon the ester used in step (a) and triphenyl phosphine salt used in step (f); l. transesterifying myristoleate as obtained in step (k) with cetyl alcohol in the presence of enzyme selected from the group consisting of Lipozyme TL IM and Novozyme 435 at temperature ranging between 65-70° C. for a period ranging between 8 to 10 hr; m. separating enzyme by filtration and evaporating the solvent to get the crude product having respective isomer of cetyl myristoleate; n. purifying the crude product as obtained in step (l) by column chromatography to obtain pure cetyl myristoleate of formula 1.