7,-Unsaturatcd acids

Caprylic acid 5-7% Oleic acid 4-8% Stearic acid 2-5% Arachidic acid 1 % Palmitoleic acid 0.4% Unsaturatcd acids 8% Saturated acids 92% (Approximate) Palmitoleic acid 1% Myristic acid 1%— Capric acid 0.5% Linolenic acid 0.4% Launc acid 0.4% Arachidic acid 0.2% Unsaturated acids 73% Lignoceric acid 1.5% Steaiic acid 1.5-3.0% Arachidic acid 1.5-2.5% Myristic 0.2% Unsaturatcd acids 82% Saturated acids 18% (Approximate) Saturated acids 27% (Approximate) Myristic acid 0.8-1.5% Linoleic acid 1-3% Palmitoleic acid 0.2-0.4% Arachidic acid 0.2-0.4% Unsaturatcd acids 50% Saturated acids 50% (Approximate) There are some significant differences m composition of palm oil (from fleshy fruit pulp) and palm kernel oil. 21 content. 

As an example of carbometallation, the 1,4-carbosilylation product 218 is obtained by the reaction of dienes, disilanes and acid chlorides of aromatic and a,/i-unsaturatcd acids at 80 °C. The phenylpalladium 216 is formed by the oxidative addition of benzoyl chloride, followed by facile decarbonylation at 80 °C, and reacts with butadiene to generate the benzyl-7i-allylic complex 217. Then, transmetallation with the disilane and reductive elimination afford 4-silyl-2-butenylbenzene 218 [92], Regioselective carbomagnesation of isoprene with allylic magnesium bromide 219 catalysed by Cp2TiCl2 gives 220, which is useful for terpene synthesis [93,94],... 

Method A Dithiocarbamic acid and ,/3 unsaturated ketones (a,/J-unsaturatcd acids). B Dithiocarbamic acid and j -halo carboxylic acids. C Dithiocarbamic acid and -propiolactone. 

The reaction is general for ortAo-substituted phenols and for a, -unsaturatcd acids, but yields are somewhat low (ca. 207 ) in the case of cresol. One useful result of this route is that the bicyclo[2.2.2]octenones are regioisomers of the adducts formed by intermolecular Diels-Alder reactions of the 2,4-dienones obtained by usual Wessely oxidation. ... 

Thiolates, generated in situ by the action of ammonium tetra-thiomolybdate on alkyl halides, thiocyanates, and disulfides, undergo conjugate addition to a, (1-unsaturatcd esters, nitriles, and ketones in water under neutral conditions (Eq. 10. II).29 Conjugate addition of thiols was also carried out in a hydrophobic ionic liquid [bmim]PF6/water-solvent system (2 1) in the absence of any acid catalyst to afford the corresponding Michael adducts in high to quantitative yields with excellent 1,4-selectivity under mild and neutral conditions (Eq. 10.12). The use of ionic liquids helps to avoid the use of either acid or base catalysts... 

Samarium enolates 60 can be easily prepared by reduction of ct-bromocarboxylic acid esters with SmT. These enolates mediated well-defined synthesis of star-shaped block co-polymers 61 (Scheme 21 ).32 32l Sml3 also mediated the formation of samarium enolates. Phenacyl thiocyanate 6233 and cr-haloketone 6434 are converted to samarium(lll) enolate intermediates 63 and 65, respectively, which undergo addition to benzaldehyde derivatives affording the corresponding oy i-unsaturatcd ketones as shown in Schemes 22 and 23. 

Regarding the first problem, the most elemental treatment consists of focusing on a few points on the gas-phase potential energy hypersurface, namely, the reactants, transition state structures and products. As an example, we will mention the work [35,36] that was done on the Meyer-Schuster reaction, an acid catalyzed rearrangement of a-acetylenic secondary and tertiary alcohols to a.p-unsaturatcd carbonyl compounds, in which the solvent plays an active role. This reaction comprises four steps. In the first, a rapid protonation takes place at the hydroxyl group. The second, which is the rate limiting step, is an apparent 1, 3-shift of the protonated hydroxyl group from carbon Ci to carbon C3. The third step is presumably a rapid allenol deprotonation, followed by a keto-enol equilibrium that leads to the final product. 

Lewis acid-catalyzed ene reactions proceed between allenyl sulfides, e.g. 330, and aldehydes 329 to afford cis-trans mixtures of 1,3-butadienes 331 (Scheme 8.90) [168, 175b], Similar ene reactions observed with imines such as 332 provide the corresponding allylamines [168,177]. It was also found that the ene reaction of 1-silylated allenyl sulfide 333 with various aldehydes (or acetals) furnishes a,/l-unsaturatcd acyl compounds such as 334 and 335 under BF3-etherate catalysis [175b]. 

Homologation via a-Haloenolates. Organoboranes can also be used to construct carbon-carbon bonds by several other types of reactions that involve migration of a boron substituent to carbon. One such reaction involves a-halocarbonyl compounds.19 For example, ethyl bromoacetate reacts with trialkylboranes in the presence of base to give alkylated acetic acid derivatives in excellent yield. The reaction is most efficiently carried out with a 9-BBN derivative. These reactions can also be effected with B-alkenyl derivatives of 9-BBN to give /i,y-unsaturatcd esters.20... 

P,y-Unsaturated ketones7i-Allylnickel halides (4, 33) react with 2-pyridyl-carboxylic acid esters to form a mixture of p,y- and a,/i-unsaturatcd ketones in which the former isomer predominates (equation I). 2-Pyridylbenzoate can be used... 

Unsaturatcd carboxylic acids arc selectively hydroxylated on the double bonds. Pentafluoro-prop-1-enyl)malonate is selectively dihydroxylated by potassium permanganate on the fluorinated carbons. The intermediate geminal fluorohydrins 3 immediately eliminate hydrogen fluoride to give dioxo esters, such as 4, as the final product (vide supra).90... 

Diazo ketone cyclizathn. Some years ago Mander and his group1 demonstrated that the protonated diazomethylcarbonyl group can initiate cyclizations in unsaturatcd systems. In the case of phenolic diazo ketones, formation of spirodienones can predominate over competing side reactions (dienone-phenol rearrangement). Tetra-fluoroboric acid or boron trifluoride etherate can be used, but trifluoroacetic acid is usually the acid of choice. 

Enamines behave in much the same way as enolate ions and enter into many of the same kinds of reactions. In the Stork reaction, for example, an enamine adds to an a,/3-unsaturated carbonyl acceptor in a Vlichael-like process. The initial product is then hydrolyzed by aqueous acid (Section 19.8) to yield a 1,5-dicarbonyl compound. The overall reaction is thus a three-step sequence of (1) enamine formation from a ketone, (2) Michael addition to an o ,j8-unsaturatcd carbonyl compound, and (3) enamine hydrolysis back to a ketone. 

Conjugate addition is also possible with a,p-unsaturatcd esters and the interesting pyridine derivative (0-51 gives a 90% yield of the conjugate addition product 52 that is 95% one diastereo-isomer. Purification and hydrolysis gives the substituted proline derivative 54 via the amino acid 53. Many variations of this theme have been played with different electrophiles. 

Reactions. In a reaction reminiscent of methylene transfer with dimethyloxo-sulfonium methylide, EDSA reacts with ,/)-unsaturatcd aldehydes and ketones in aprotic solvents to give cyclopropanes in 65-90% yield.1 EDSA reacts with ,/3-unsaturated esters to give esters of acyclic polybasic acids.2... 

The a j3 ratio is suspiciously dependent upon the solvent, coordination may be playing a part here too, and there is a further complication in both series. For nucleophilic attack on a carbonyl to take place, coordination to the oxygen atom by a Lewis or protic acid is often necessary, as we have already seen with n, T-unsaturatcd ketones. This means that there is a pre-equilibrium step between the bare carbonyl compound, used in the calculations, and the reactive species. There will be a higher concentration of the intermediate with the metal or other catalyst coordinated to the more basic of the two carbonyl groups, which will be the (3 carbonyl in 4.171. However, when the coordination is to the less basic carbonyl group, it will create a more reactive species. The balance of all these effects is hard to predict, and the overall story is too complicated for simple analysis. This is not an uncommon situation, and care must be taken in any analysis of subtle steric and electronic effects like those operating here and in much of the discussion about enones above. 

---