Unsaturated carboxylic add

J.-L Xiao, S. C. A Nefkens, P. G. Jessop, T. Ikariya, R. Noyori, Asymmetric Hydrogenation of a, -Unsaturated Carboxylic Adds in Supercritical Carbon Dioxide , Tetrahedron Lett. 1996,37,2813-2816. 

Reduction of unsaturated carboxylic adds gives products that you might alternatively think of making by auxiliary-controlled alkylation methods. When the NutraSweet company needed this chiral branched carboxylic acid as a single enantiomer, they initially used the auxiliary methods of p. 1110 to make a small amount, but they found that ruthenium-catalysed hydrogenation was greatly to be preferred on a large scale just 22 g of the ruthenium-(5)-BINAP complex is needed to produce SO kg of product with 90% ee. 

Conjugate addition (1,4 addition) of pyridine and ionization of a carboxylic acid are followed by decarboxylation and concomitant elimination of pyridine to yield the a,p-unsaturated carboxylic add as shown here. 

Unsaturated Carboxylic Add Amides, Esters, and Nitriles Enantioselective hydroformylation of dialkylacrylamides was investigated by Clarke and coworkers in detail (Scheme 4.81) [56]. It was found that these substrates undergo hydroformylation more slowly than styrene. Up to 82% ee was realized in the best trials. A serious problem was caused by the epimerization of chiral aldehydes by the intermediarily formed umnodified rhodium hydride complexes. Therefore, the reaction times should be kept short, and low temperatures are recommended. 

Unsaturated carboxylic adds (23) can be electrolytically decarboxylated to allylic acetates (24) in 80—90% yield. a-Phenylthiocarboxylic acids can also be decarboxylated electrolytically to give high yields of aldehyde acetals (c/. 3, 49). Electrolytic procedures are also useful for the conversion of malonic acids into ketones. " This method has been used to prepare valerolactones from cyclic ethers (25), themselves prepared by Diels-Alder reactions between dienes and ketomalonates. ... 

Zhao, X., Alper, H. and Yu, Z. (2006) Stereoselective hydroxycarbonylation of vinyl bromides to a,p-unsaturated carboxylic adds in the ionic hquid [BMIM]... 

Esters of allylic alcohols can be rearranged to %5-unsaturated carboxylic adds via the O-trimethylsilyl ethers of the ester enolate. This rearrangement takes place under much milder conditions than for the orthoester method. The reaction occurs at room temperature or slightly above. Entries 10, 11, and 13 of Scheme 6.11 are examples. The example in entry 12 is a rearrangement on the enolate without intervention of the silyl enol ether. 

Deng J, Duan Z-C, Huang J-D, Hu X-P, Wang D-Y, Yu S-B, Xu X-F, Zheng Z. Rh-Catalyzed asymmetric hydrogenation of y-phthalimido-substituted y,p-unsaturated carboxylic add esters an effident enantioselective synthesis of P-aryl-y-amino adds. Org. Lett. 2007 9(23) 4825-4828. 

Water can add reversibly to o ,/3-unsalurated aldehydes and ketones to yield /3-hydroxy aldehydes and ketones, although the position of the equilibrium generally favors unsaturated reactant rather than saturated adduct. A related addition to an c /S-unsaturated carboxylic acid occurs in numerous biological pathways, such as the citric acid cycle of food metabolism where ds-aconitate is converted into isocitrate by conjugate addition of water to a double bond. 

Electrolysis, under similar conditions, of a mixture of two carboxyUc acids RCOOH and R COOH leads, in addition to normal coupling products R—R and R —R, to cross coupling R— R. If a mixture of a saturated carboxylic add and a half-ester of an ouo-dicarboxylic acid is electrolysed, there are three main products, viz., a hydrocarbon (I), a mono-ester (II), and a di-ester (HI) and these are readily separable by distillation. Some unsaturated ester (IV) is often present in small quantity. 

The benzotriazolyl derivative of acrolein acetal, compound 882, is lithiated, treated with chlorodiphenylphosphine, and the obtained intermediate is oxidized with hydrogen peroxide to phosphine oxide 883 (Scheme 145). The relatively acidic proton in derivative 883 is easily removed by a base, and the obtained anion adds to a carbonyl group of aldehyde or ketone. Subsequent rearrangement and elimination of the phosphorane group generates diene 884. For the derivatives of aldehydes (884, R2 = H), (E)-(E) stereoselectivity of the elimination is observed. Acidic alcoholysis of dienes 884 affords esters of P,y-unsaturated carboxylic acids 885 < 1997JOC4131>. 

Monohydnc alcohols are named by adding -01 to a molecular skeleton name. Carbon chains, unsaturation, etc., are numbered in a manner analogous to that used for carboxylic adds. (See preceding section.)... 

Both, strained and unsaturated organic molecules are known to form cation radicals as a result of electron transfer to photoexdted sensitizers (excited-state oxidants). The resulting cation radical-anion radical pairs can undergo a variety of reactions, including back electron transfer, nucleophilic attack on to the cation radical, electrophilic attack on the anion radical, reduction of anion radical, and addition of anion radical to the cation radical. This concept has been nicely demonstrated by Gassman et al. [103, 104], using the photoinduced electron-transfer cydization of y,8-unsatu-rated carboxylic add 232 to y-ladones 233 and 234 as an example (see Scheme 8.65). 

The aluminum tellurolate is very sensitive towards air and moisture and, therefore, is not isolated but used in situ. Aluminum benzenetellurolates add to a-enones and to oc,fi-unsaturated carboxylic acid esters. The adducts can be hydrolyzed to /i-phenyltelluro carbonyl compounds or reacted with an aldehyde1. 

Esterification. Boron thfluoride etherale in combination with a large excess of an alcohol is an elTeclive reagent for the esterification of 4-aminobenzoic acid. The combination is particularly useful for esterification of unsaturated carboxylic acids. The boron trifluoridc etherate alcohol reaction is particularly useful for esterification of heterocyclic carboxylic adds. ... 

The occurrence of C8 and C9 dicarboxylic adds in samples of atmospheric particles and in recent sediments (Stephanou 1992 Steph-anou and Stratigakis 1993) has been attributed to photochemical degradation of unsaturated carboxylic acids that are widespread in almost all biota. 

The hydrocarboxylation of an unsaturated fatty add ester is carried out in a single organic phase. As product, the monoester of a dicarboxylic add is formed. When this produd is treated with aqueous sodium hydroxide solution this add is converted into a water-soluble sodium salt. In the following separator the water-insoluble palladium catalyst is extracted from the aqueous phase by addition of an organic solvent. When the aqueous product phase is addified with aqueous hydrochloride solution the released carboxylic acid forms a second organic phase and can easily be separated. The catalyst-containing solvent phase passes a distillation step, thus recycling the solvent to the separator and the palladium catalyst to the reactor. 

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