ISSN:
0947-3440
Keywords:
Anacardic acids
;
Benzoates, methyl 6-alkyl-2-methoxy-
;
2-Alkynoates, methyl
;
Aluminium triiodide, demethylation by treatment with
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The anacardic acids 1-11, isolated from various plants, were synthesized by a new general method. Reaction of the methyl alkynoates 12-18 with 1-methoxy-1,4-cyclohexadiene at 200°C afforded directly the methyl 2-methoxybenzoates 19-25 with long chain substituents in 6-position in 74-85% yield. The dienophiles 12-16 were prepared by pyrolysis of the corresponding acylphosphoranes 26-30, the dienophiles 17 and 18 by methoxycarbonylation of the corresponding alkynes 31 and 32 via the hydroxy esters 33 and 34. Demethylation of 19-23 with All3 gave the methyl salicylates 35-39 which could be hydrolized to the anacardic acids 1-4 and 7. Hydrolysis of 24 and 25 provided the hydroxy acids 40 and 41, which were converted by treatment with CBr4/PPh3 into the acids 42 and 43 bearing bromoalkyl side chains. These were transformed into 44-47 by reaction with 1-hexynyllithium and 1-octynyllithium. Stereoselective hydrogenation of 44-47 gave 48-51 with (Z)-alkene side chains. In a similar approach 42 was converted into 52 and then into 53, which gave upon treatment with 1-pentynylmagnesium bromide or 1-heptynylmagnesium bromide the acids 54 and 55 with alkadiyne side chains. Stereoselective hydrogenation provided 56 and 57 with (Z,Z)-alkadiene side chains. The 2-methoxy group in 48-51, 56, 57 was demethylated by treatment with All3 to give the anacardic acids 5, 6, 8-11.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.1995199512307
Permalink
