Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 11, 2002
Publication Date: April 1, 2002
Citation: KENAR, J.A. REDUCTION OF FATTY ESTER DELTA2-ISOXAZOLINE HETEROCYCLES. PREPARATION OF FATTY ESTERS CONTAINING THE BETA-HYDROXY KETONE MOIETY. JOURNAL OF THE AMERICAN OIL CHEMISTS' SOCIETY. v.79. pp.351-356. 2002. Interpretive Summary: The current social climate regarding environmental issues and pollution related to the use and waste disposal of non-renewable resources (petroleum based products) in industrial applications has clearly underscored the importance of utilizing renewable resources for these applications. Only through continued research to effectively modify lipids and vegetable oils, in an effort to tailor their physical properties to the needs of industry, will renewable resources be able to enter petroleum dominated chemical markets. We successfully used chemical reactions to introduce useful hydroxyl and ketone functionalities onto the structure of renewable resource derived lipid intermediates. This method may provide scientists with a convenient tool for obtaining new types of modified fatty lipids with useful physical and chemical properties not readily accessible by current methods. These new oleochemicals may have application as bio-based surfactants, emulsifiers, or wetting agents. Finding new methods to effectively modify fatty acids and vegetable oils obtained from renewable resources and obtain bio-based industrial products not only benefits United States farmers, but also the environment and will help to decrease our dependence on the ever tightening supply of non- renewable resources.
Technical Abstract: Fatty ester compounds containing the beta-hydroxy ketone moiety were prepared in good yields from their corresponding fatty delta2- isoxazoline heterocyclic precursors by a reductive hydrogenolysis- hydrolysis procedure using Raney nickel. By this methodology, C-17, C- 18 and C-19 straight chain fatty methyl esters containing the 10-hydroxy 12-keto moieties were prepared in 73 %, 83 % and 92 %, respectively from their corresponding isoxazoline fatty ester compounds. Additionally, two other 10-hydroxy 12-keto C-12 and C-14 fatty ester compounds were prepared in 84% and 92% yield, respectively. The C-12 beta-hydroxy ketone contains a phenyl ring at C-12 while the C-14 beta-hydroxy ketone compound has two methyl substituents at C-13. Gas chromatography-mass spectrometry using electron impact ionization is an efficient characterization method for these fatty beta-hydroxy ketones, and the positions of the hydroxyl and ketone functionalities are easily determined after conversion of the hydroxyl group into its trimethylsilyl ether. The precursor fatty ester delta2-isoxazoline heterocycles used in this study are readily available in one step from a 1,3-dipolar cycloaddition reaction between nitrile oxides and methyl 10- undecenoate. This overall two-step sequence, 1,3-dipolar cycloaddition followed by reductive ring opening, represents a convenient method to construct fatty ester compounds containing the beta-hydroxy ketone functionality not easily accessible by other methods.