Isomerization of anacardic acid: A possible route to the synthesis of an unsaturated benzolactone and a kairomone

Abstract

Dedicated to Proifessor Frank Gunstone, an outstanding researcher of fats and oils and a great friend, on the occasion of his 90th birthday.Crystalline unsaturated lactone, 8-hydroxy-3-tridecyl-1H-isochromen-1-one (6) has been synthesized by isomerization of anacardic acid having heterogeneous alkyl side chains (a mixture of mono-, di-, and tri-unsaturated anacardic acid) (1). Hydrogenation of 8-hydroxy-3-tridecyl-1H-isochromen-1-one produced a saturated lactone, 8-hydroxy-3-tridecyl-3,4-dihydroisochromen-1-one (7). Isomerization of monoene anacardic acid resulted in a crystalline isoanacardic acid, (E)-2-hydroxy-6-(pentadec-1-enyl) benzoic acid (8) as a major product. This was then metathesized with 2-butene to give 3-prop-1enylphenol (10). Both isomerization reactions used a 1,2-bis(ditertiarybutylphosphinomethyl)benzene modified palladium catalyst. The two products, 8-hydroxy-3-tridecyl-1H-isochromen-1-one and (E)-2hydroxy-6-(pentadec-1-enyl)benzoic acid have been crystallographically characterized.Practical applications: Unsaturated lactones are structural elements often found in natural products, which have medicinal value. Benzolactones derived from anacardic acid reported in this work have some structural similarity with lactones such as massoia lactone having medicinal value. Therefore with this idea in mind, the unsaturated benzolactones reported in this work will be tested for their anti pathogenic activity. 3-Propylphenol is used in combination with racemic 1-octen-3-ol and p-cresol to prepare a kairomone for tsetse fly traps. Results from this work describe the suitability of anacardic acid for synthesizing 3-propylphenol. The fact that 3-propylphenol can be synthesized from anacardic acid, a component of cashew nut shell liquid is of particular interest since most of the areas affected with tsetse flies are suitable for growing cashew plants. This means the raw materials (CNSL) for synthesis of 3-propylphenol will be obtained from within the same region where the kairomone is to be applied, although we appreciate that specialized facilities would be required for the types of transformation described.

Synthesis of Bifunctional Monomers by the Palladium‐Catalyzed Carbonylation of Cardanol and its Derivatives

“…The same monomer could be synthesized by the methoxycarbonylation of monoene anacardic acid, obtained from the transfer hydrogenation of anacardic acid as the starting material in a similar yield (65 %). The methoxycarbonylated anacardic acid must be then be decarboxylated to produce the desired monomer (58 % overall yield; Scheme ).…”

“…CNSL was obtained from the shells by the solvent extraction method . Anacardic acid, cardanol ( 1 ), monoene cardanol, monoene anacardic acid, and 3‐(non‐8‐enyl)phenol; HOPhC 9 ‐ene ( 5 ) were obtained by methods reported previously. All reactions were performed using standard Schlenk line and glovebox techniques.…”

“…Method 2 : The methoxycarbonylation of monoene anacardic acid was performed as for the methoxycarbonylation of cardanol to yield 2‐hydroxy‐6‐(16‐methoxy‐16‐oxohexadecyl)benzoic acid in 66 % isolated yield. 1 H NMR (400 Hz; CDCl 3 ): δ =1.07–1.49 (m, 22 H; −CH 2 −, alkyl chain), 1.54–1.73 (m, 4 H; −CH 2 −), 2.33 (t, 3 J (H,H)=8.1, 2 H; −CH 2 −), 3.01 (t, 3 J (H,H)=8.2, 2 H; −CH 2 −), 3.70 (s, 3 H; −OCH 3 ), 6.80 (d, 3 J (H,H)=7.5, 1 H; Ar‐H), 6.90 (d, 3 J (H,H)=8.98, 1 H; Ar‐H), 7.38 (t, 3 J (H,H)=8.98, 1 H; Ar‐H), 11.11 ppm (s, 1 H; −COOH); 13 C NMR (100 Hz; CDCl 3 ): δ =25.3, 29.8, 32.4, 34.9, 37.0 (−CH 2 −), 52.0 (−OCH 3 ), 116.4 (Ar‐CH−), 123.1 (Ar‐CH−), 136.0 (Ar‐CH−), 148.0 (Ar‐C−R), 163.9 (Ar‐C−OH), 175.9 ppm (R−COOMe); elemental analysis calcd (%) for C 24 H 38 O 5 (406.27): C 70.90, H 9.42; found: C 70.77, H 9.54.…”

Synthesis of a tyrosinase inhibitor by consecutive ethenolysis and cross-metathesis of crude cashew nutshell liquid

“…However, the separation and purification of this CNSL component without decarboxylation is laborious and relies on wasteful and tedious processes such as fractionate precipitation or column chromatography [6,17]. A limited number of derivatizations of anacardic acid are reported by now, including the synthesis of lactones [18–20], sulfonamides [21] or hydrazones [22], typically bioactive compounds though with low commercial value. However, several studies suggest that anacardic acid and its derivatives display a broad range of biological activities such as antimicrobial [23], antioxidant [24], molluscicidal [25] and antiplaque [26].…”

Fats and oils as renewable feedstock for the chemical industry

“…Y. Peng et al explored the potential of ring‐opening cross‐metathesis of highly functionalized sophorolipids, which are accessible in large amounts by fermentation, to expand the range of modified sophorolipids‐based surfactants by chemical transformations. J. G. Mgaya et al used cashew nut shell liquid, a renewable resource containing aromatic moieties which is a byproduct of cashew processing factories, as substrate for catalytic isomerization of the double bond followed by metathesis, yielding 3‐propylphenol, a kairomone of the tsetse fly . Using the same substrate, E. Darroman et al presented a synthesis of a new biobased aromatic amine and its use in the formulation of epoxy resins .…”