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Allylic oxidation of methyl 10‐undecenoate and nucleophilic additions to methyl 9‐oxo‐10‐undecenoate
Author(s) -
Hinkamp Ludger,
Schäfer Hans J.
Publication year - 2015
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/ejlt.201400238
Subject(s) - chemistry , sodium methoxide , dimethyl malonate , nucleophile , organic chemistry , michael reaction , enone , electrophile , medicinal chemistry , trimethylsilyl cyanide , yield (engineering) , methanol , catalysis , enantioselective synthesis , materials science , metallurgy
Methyl 10‐undecenoate ( 2b ) has been oxidized with tert ‐butyl hydroperoxide/selenium dioxide and potassium dichromate to 53% of methyl 9‐oxo‐10‐undecenoate ( 4 ). Based on the conversion of 2b , the yield of 4 is 81%. Residual selenium in ester 5 was determined to be less than 1 ppm. The electrophilic double bond in enone 4 reacts in good to excellent yield with a variety of nucleophiles. With dimethyl malonate, acetylacetone, and methyl acetoacetate Michael –adducts at C‐11 of enone 4 were obtained in 88–99% yield. Corresponding additions were achieved with nitroethane, 1‐ and 2‐nitropropane in 78–89% yield. In a Nef –reaction some nitroalkyl adducts were converted to methyl esters of 9,12‐dioxofatty acids in 99% yield. In methanol/sodium methoxide the ester methyl 11‐methoxy‐9‐oxoundecanoate was obtained in 86% yield from enone 4 . In a three step reaction with ammonium chloride/sodium cyanide, hydrochloric acid/acetic acid, and methanol/2,2‐dimethoxypropane the ester 4 yielded 63% of dimethyl 4‐oxo‐dodecanedioate. With the cyanide ion the electrophilic carbon atom in aldehydes can be converted into a nucleophile ( Stetter –reaction). Catalysed by sodium cyanide in DMF aromatic and heteroaromatic aldehydes RCHO with R = phenyl, 2‐thienyl, 2‐furyl and 3‐pyridyl were added to enone 4 to afford methyl 12‐aryl‐ and methyl 12‐heteroaryl‐9,12‐dioxododecanoates in 54–73% yield. Practical applications: The prepared oleochemicals are useful as precursors for pharmaceuticals and as monomers for polyesters and polyamides. They also may be applied to synthesize fatty acid conjugates by providing suitable connectors for biological active compounds and to attach groups with suitable physical properties for materials. For enone 4 prepared from methyl 10‐undecenoate, thirteen Michael additions with 1,3‐dicarbonyl and nitro alkyl compounds, hydrocyanic acid and acyl anions are reported.