Carboxylic acids with alkenes

This reaction is clearly related to forming esters and lactones by reaction of carboxylic acids with alkenes (15-6), but the manganese reagent leads to... 

The reactions of water, alcohols and carboxylic acids with alkenes are explained by these three reaction paths. Formation of acetaldehyde from ethylene, water and PdCb is understood by the sequence of hydroxypalladation to form 5, followed by hydride shift. It has been confirmed that no incorporation of deuterium occurs by the reaction of ethylene with PdCl2 carried out in D2O, and the four hydrogens in ethylene are retained in acetaldehyde, indicating that hydride shift occurs (path c) [1]. Therefore, free vinyl alcohol (6), expected to be formed by )3-H elimination (path a), is not an intermediate (path c). In the presence of LiCl, 2-chloroethanol (7) is obtained by path b. 

In 2011, Ueyama et al. [68] reported the ruthenium-catalyzed oxidative vinylation of heteroarene carboxylic acids with alkenes. The vinylation occurred at the C3-position of the heteroaromatic substrate (Figure 4.34). 

Treatment of indole-3-carboxylic acids with alkenes in the presence of Pd(OAc)2 (5mol%), Cu(0Ac)2 H20 (2equiv.), and LiOAc (3equiv.) in DMAc at 140 C gives rise to C2-alkenylated indoles through carboxylic group directed... 

Reaction with Carboxylic Acids The intramolecular reaction of carboxylic acids with alkenes affords unsaturated lactones (eq 14).i ... 

After the seminal work reported by Satoh and Miura in early 2011 on ruthenium-catalyzed oxidative vinylation of heteroarene carboxylic acids with alkenes [17], Ackermann demonstrated a ruthenium(ll)-catalyzed cross-dehydrogenative C-H bond alkenylations of benzoic acid derivatives with acrylonitrile or alkyl acrylates. Following the oxidative C—H bond alkenylation reaction, subsequent intramolecular oxa-Michael reaction occurred leading to phthalides in good yields (Eq. (7.12)) [18]. The reactions took place with water as an environmentally benign medium under mild conditions. 

We will now explore each aspect of this two-step process. In the first step, a peroxyacid (RCO3H), sometimes called a per-acid, reacts with the alkene. Compare the structure of a carboxylic acid with the structure of a peroxy acid ... 

The supported Co2+-substituted Wells-Dawson POM, Cs6H2[P2W17061Co(OH2)], on silica was stable up to 773 K and catalyzed the heterogeneous oxidation of various aldehydes to the corresponding carboxylic acids with 02 as a sole oxidant [116], The H5PV2Mo10O40 POM, impregnated onto meso-porous MCM-41, catalyzed the aerobic oxidation of alkanes and alkenes using isobutyraldehyde as a... 

Less rigorous reaction conditions are required to cleave the double bond to form ketones and carboxylic acids. Phase-transfer-assisted permanganate oxidations in the presence of quaternary ammonium salts,439 652-654 crown ethers,439,655 or polyethers566 usually ensure high yields. Terminal alkenes are transformed to carboxylic acids with one carbon atom less than the starting compound.653,654... 

Terminal alkynes are prone to undergo facile oxidative cleavage to yield carboxylic acids with loss of the terminal carbon atom. In fact, most of the oxidizing agents that can be used in the selective oxidation of internal alkenes to 1,2-diketones [Ru04,711 PhIO with Ru catalysts,712 KMn04,713 T1(N03)3,716 0s04718] convert terminal alkynes to carboxylic acids. 

Esterification of carboxylic acids with bulky alcohols is unsatisfactory. However, tertiary alkyl esters often can be prepared by addition of the acid to the appropriate alkene using an acid catalyst ... 

A somewhat similar decarboxylation reaction with formation of an alkene can be achieved by heating a carboxylic acid with lead tetraethanoate, Pb(02CCH3)4, in the presence of a catalytic amount of Cu(OCH3)2. A useful example is... 

Non-oxidative hydrocarboxylation of alkenes to carboxylic acids with CO and H20 is catalyzed by palladium complexes such as PdCl2(PhCN)2 or PdCl2(PPh3)2, and a-methyl acids predominate in the presence of HC1.374,443 A recent improvement of this reaction consisted of the use of a PdCl2/CuCl2/HCl catalyst under oxidative conditions.377 Almost quantitative yields of a-methyl carboxylic acids and dicarboxylic acids were obtained from terminal alkenes and terminal dialkenes respectively, at room temperature and atmospheric pressure (equation 174).377... 

A wide variety of unsaturated carboxylic acids have been allowed to react with HBr.101 Carboxylic acids with remote C—C double bonds react as simple alkenes.138,139 4-Pentenoic acid reacts with HBr neat or in a polar solvent to give exclusively 4-bromopentanoic acid, but the reaction in nonpolar solvents affords only 5-bromopentanoic acid.136 On the other hand, 5-methyl-4-hexenoic acid produces only the S-bromo acid. A similar pattern is followed by 3-butenoic, 3-pentenoic and 4-methyl-3-pentenoic acids. No matter what the substitution pattern, 2-alkenoic acids always favor the 3-bromo acid.113,136,140,141 Addition of HBr to cyclic a,3-unsaturated acids initially forms predominantly the product of trans diaxial addition which upon longer reaction time or higher temperature isomerizes to the trans product (equation 92).57,141,142 Similar observations have been made on bicyclic a.fj-unsaturated acids.141... 

With this, the formation of the 2-alkene-l-ol, 2-alkene-l-al, 2-alkene-1-carboxylic acid, l-alkene-3-ol and l-alkene-2-one is predestined. 

An alternative preparation of one-carbon-extended carboxylic acids from alkenes via hydroboration has been most recently reported. Various 2-alkyl-l,3,2-dithiaboro-lanes (28) readily prepared from alkenes by the hydroboration with BHBr2 SMe2 followed by treatment with a suspension of lithium alkylthiolate in pentane, are... 

Dehydrative decarboxylation. The convc sion of p-hydroxy carboxylic acids to alkenes by reaction with a DMF dialkyl acetal iirvolves an r/n/Z-elimination, and thus is complementary to the known. yv/i-elimination of these hydroxy acids via a P-lactone (5, 22 9, 504). These reactions were used to obtain both the (E)- and the (Z)-l-alkoxy-l,3-... 

A The alkynyl hydrogen of propyne is acidic and hence the propyne will form an organometallic derivative. The Grignard derivative will react with carbon dioxide to give the carboxylic acid. Cis alkenes are formed by the catalytic hydrogenation of alkynes using a Lindlar catalyst. Hence a propynyl alcohol is a precursor to compound (b). This could be obtained by the addition of a propyne anion to propanone ... 

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