title: Novel halo-oxo-allenic fatty ester derivatives from epoxidized methyl santalbate (methyl trans-11-octadecen-9-ynoate).
abstract: Methyl santalbate (methyl trans-11-octadecen-9-ynoate) from Sandal wood seed oil, Santalbum alum) was epoxidized to methyl trans-11,12-epoxy-octadec-9-ynoate (1). Treatment of compound 1 with tetrabutylammonium dihydrogentrifluoride, and boron trifluoride etherate gave the corresponding anti- (2a) (57%) and syn- (2b) (35%) fluorohydrin derivatives, respectively. These reactions were regio- and stereoselective in nature. The structures of the anti- and syn- isomers were confirmed by NMR spectroscopy. Ring opening of the epoxy system of compound 1 with lithium chloride gave the anti-chlorohydrin derivative (3) (89%). Oxidation of either compound 2a or 2b gave the same fluoro-keto acetylenic fatty ester (4) (75%), and compound 3 on chromic acid oxidation yielded the corresponding chloro-keto acetylene (5) (73%). Isomerization of compounds 4 and 5 with potassium carbonate in dichloromethane furnished the requisite fluoro-allenic (6) (63%, methyl 11-fluoro-12-oxo-9,10-octadecadienoate) and chloro-allenic (7) (80%, methyl 11-chloro-12-oxo-9,10-octadecadienoate) C(18) fatty esters. All products were confirmed by a combination of spectrometric and spectroscopic techniques.
mesh_terms: D000466:Alkadienes / Q000138:chemical synthesis* / Q000737:chemistry; D001880:Boranes / Q000737:chemistry; D004852:Epoxy Compounds / Q000737:chemistry; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D006846:Hydrocarbons, Halogenated / Q000138:chemical synthesis* / Q000737:chemistry; D007536:Isomerism; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D018021:Lithium Chloride / Q000737:chemistry; D009829:Oleic Acids / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: D000466:Alkadienes; D001880:Boranes; D004852:Epoxy Compounds; D005231:Fatty Acids, Unsaturated; D006846:Hydrocarbons, Halogenated; D007659:Ketones; D009829:Oleic Acids; C101707:boron trifluoride etherate; C025947:propadiene; D018021:Lithium Chloride; C053760:ximenynic acid