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Synthesis of novel tri‐ and tetrasubstituted C 18 furan fatty esters
Author(s) -
Lie Ken Jie Marcel S. F.,
Lau Maureen M. L.,
Lam Corey N. W.
Publication year - 2003
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-003-1192-8
Subject(s) - furan , chemistry , allyl bromide , benzonitrile , bromide , medicinal chemistry , halogenation , palladium , organic chemistry , catalysis
A methylene‐interrupted C 18 keto‐acetylenic fatty ester (methyl 12‐oxo‐9‐octadecynoate) was obtained from methyl ricinoleate by bromination‐dehydrobromination followed by oxidation. Reaction of methyl 12‐oxo‐9‐octadecynoate with bis(benzonitrile) palladium(II) chloride, allyl bromide, or methyl‐allyl bromide furnished methyl 8‐[5‐hexyl‐3‐allyl‐furan‐2‐yl]‐octanoate ( 1 , 56%) or methyl 8‐[5‐hexyl‐3‐(2‐methyl‐allyl)‐furan‐2‐yl]‐octanoate ( 2 , 55%). Reaction of methyl 12‐oxo‐11‐chloro‐or 11‐fluoro‐9‐octadeyynoate (prepared from methyl santalbate‐methyl 11‐ E ‐9‐octadecynoate, found in sandalwood, Santalum album , seed oil) with bis(benzonitrile) palladium(II) chloride gave methyl 8‐(4‐fluoro‐5‐hexyl‐furan‐2‐yl)‐octanoate ( 3 , 50%) or methyl 8‐(4‐fluoro‐5‐hexyl‐furan‐2‐yl)‐octanoate ( 4 , 50%), respectively. And when methyl 12‐oxo‐11‐chloro‐ or 11‐fluoro‐9‐octadecynoate was treated with a mixture of bis(benzonitrile) palladium(II) chloride, allyl bromide, or methyl‐allyl bromide, the reaction yielded tetrasubstituted C 18 furan derivatives, viz , methyl 8‐(3‐allyl‐4‐chloro‐5‐hexyl‐furan‐2‐yl)‐octanoate ( 5 , 54%), methyl 8‐[4‐chloro‐5‐hexyl‐3‐(2‐methyl‐allyl)‐furan‐2‐yl)‐octanoate ( 6 , 54%), methyl 8‐(3‐allyl‐4‐fluoro‐5‐hexyl‐furan‐2‐yl]‐octanoate ( 7 , 10%), and methyl 8‐[4‐fluoro‐5‐hexyl‐3‐(2‐methyl‐allyl)‐furan‐2‐yl]‐octanoate ( 8 , 10%). The presence of a fluorine atom in the furan derivatives 4, 7 , and 8 was readily characterized by the appearance of doublets for carbon nuclei, which were coupled to the fluorine atom in the 13 C NMR spectra. All furan fatty derivatives from this work were characterized by NMR spectroscopic and mass spectrometric analyses. The yields of compounds 7 and 8 were very low (10%) despite attempts to improve the procedure by increasing the amounts of the reactants and catalyst.