Additions carboxylic acids, palladium chloride

Benzoic acid and naphthoic acid are formed by the oxidative carbonylation by use of Pd(OAc)2 in AcOH. t-Bu02H and allyl chloride are used as reoxidants. Addition of phenanthroline gives a favorable effect[360], Furan and thiophene are also carbonylated selectively at the 2-position[361,362]. fndole-3-carboxylic acid is prepared by the carboxylation of 1-acetylindole using Pd(OAc)2 and peroxodisulfate (Na2S208)[362aj. Benzoic acid derivatives are obtained by the reaction of benzene derivatives with sodium palladium mal-onate in refluxing AcOH[363]. 

Anhydrides are reduced with relative ease. McAlees and McCrindle 20) established the following increasing order of difficulty for various carbonyls acid chlorides > aldehydes, ketones > anhydrides > esters > carboxylic acids > amides. Reduction may proceed by 1,2-addilion of hydrogen or by cleavage of an oxygen-carbonyl bond. If 1,2-addition to the carbonyl occurs, as in the presence of strong protic acids over palladium, 1,1-diesters are formed by acylation 26). 

Synthesis of isomeric chiral protected (63 )-6-amino-hexahydro-2,7-dioxopyrazolo[l,2- ]pyrazole-l-carboxylic acid 280 is shown in Scheme 36. Crude vinyl phosphonate 275, obtained by treatment of diethyl allyloxycarbonylmethyl-phosphonate with acetic anhydride and tetramethyl diaminomethane as a formaldehyde equivalent, was used in the Michael addition to chiral 4-(f-butoxycarbonylamino)pyrazolidin-3-one 272. The Michael addition is run in dichloro-methane followed by addition of f-butyl oxalyl chloride and 2 equiv of Huning s base in the same pot to provide 276 in 58% yield. The allyl ester is deprotected using palladium catalysis to give the corresponding acid 277, which is... 

Palladium, benzylchlorobis(triphenylphosphine)-, trans-, 67, 86 Palladium-catalyzed aryl-aryl coupling, 66, 70 PALLADIUM-CATALYZED ALLYLIC AMINATION, 67,105 PALLADIUM-CATALYZED CHLOROACETOXYLATION, 67, 105 PALLADIUM-CATALYZED COUPLING OF ACID CHLORIDES WITH ORGANOTIN REAGENTS, 67, 86 PALLADIUM-CATALYZED COUPLING OF ARYL HALIDES, 66, 67 PALLADIUM-CATALYZED syn-ADDITION OF CARBOXYLIC ACIDS,... 

As carboxylic acid additives increased the efficiency of palladium catalysts in direct arylations through a cooperative deprotonation/metallation mechanism (see Chapter 11) [45], their application to ruthenium catalysis was tested. Thus, it was found that a ruthenium complex modified with carboxylic acid MesC02H (96) displayed a broad scope and allowed for the efficient directed arylation of triazoles, pyridines, pyrazoles or oxazolines [44, 46). With respect to the electrophile, aryl bromides, chlorides and tosylates, including ortho-substituted derivatives, were found to be viable substrates. It should be noted here that these direct arylations could be performed at a lower reaction temperatures of 80 °C (Scheme 9.34). 

The main field of application for benzoic acid is the production of phenol however, the significance of this phenol route has declined in recent years. Additionally, benzoic acid is used in the production of benzoyl chloride and sodium benzoate. In Italy, benzoic acid is used as the raw material for the production of 8-caprolactam, in a process developed by Snia Viscosa, This involves hydrogenating benzoic add at 170 °C and 15 bar over a palladium catalyst, purifying the cyclohexane carboxylic acid by distillation followed by its reaction with nitrosyl-sulfuric acid to yield 8-caprolactam. 

On the other hand, the oxidative addition of aliphatic acid chlorides occurs in the absence of alkyne, but the oxidative addition complex could not be isolated due to fast decarbonylation followed by facile /1-hydrogen elimination. The decarbonylation of carboxylic acid was reported with palladium catalysts as well [47-56], In general, the reactions to acid anhydride as the intermediate need relatively high temperatures. 

Palladium-catalyzed intermolecular oxidations of dienes with carboxylic acids and alcohols as donors give 1,4-addition products. This chemistry has been studied extensively by Backvall. Early studies involved 1,4-additions of two acetoxy or alkoxy groups across a diene,More recently, intermolecular additions of two different nucleophiles have been developed. The ability to control the stereochemistry of the additions across cyclic dienes makes this procedure particularly valuable. As shown in Scheme 16.25, conditions for either cis or trans additions have been developed. Reactions conducted in the absence of added chloride form products from trans 1,4-addition, while reactions conducted in the presence of added chloride form products from cis 1,4-addition. 

The conversion of acetylenes into olefinic esters by use of addition reactions has been illustrated by the following two examples, (i) 1-Alkenyl boranes, which are readily prepared by the hydroboration of alkynes, are converted into a,fi-unsaturated carboxylic esters in good yield by reaction with carbon monoxide in the presence of palladium chloride and sodium acetate in methanol the process is carried out at atmospheric pressure and occurs with retention of configuration with respect to the alkenyl borane. (ii) Carboxylic acids add to acetylenes in the presence of silver carbonate to provide a novel synthesis of enol esters, which are formed in an 8 2 mixture of isomers. ... 

The crude enamine is dissolved in 450 ml. of ether, and the solution is transferred to a 1-1. three-necked flask equipped with a sealed stirrer, a 250-ml. dropping funnel, and a two-necked adapter fitted with a calcium chloride tube and a thermometer immersed in the solution. A solution of 71-76 g. (0.85-0.90 mole) (Note 5) of methyl propiolate (Caution Methyl propiolate is a severe lachrymator and should he handled only in the hood.) in 150 ml. of ether is added dropwise. During the addition the temperature of the mixture is maintained at 25-30° by periodic cooling of the reaction flask in a dry ice-acetone bath. When the addition is almost complete, a white solid begins to separate. The mixture is stirred at 25-30° for an additional hour, cooled to 0°, and filtered to remove the solid. This is dissolved in 700 ml. of 6% hydrochloric acid (Note 6), the acidic solution is warmed at 55-60° for 1 hour, and the mixture is cooled and extracted with two 100-ml. portions of ether. The ether is removed on a steam bath, and the residue of crude methyl 10-oxocyclodec-2-ene-l-carboxylate is dissolved in 300 ml. of methanol and hydrogenated over 5 g. of 5% palladium-on-alumina catalyst at 40 p.s.i. pressure and room temperature. 

The hydrophilic palladium complex (2) was also a good catalyst for the carboxylation of benzyl halides under heptane-water two-phase conditions [20]. Benzyl chloride and bromide give phenylacetic acid in high yields under mild conditions (Eq. 5). However, the biphasic carboxylation with PdCI2(PPH,) , is very slow, and gives a considerable amount of benzyl alcohol. The addition of a normal PTC such... 

With hydrogen peroxide or, better, t-butylhydroperoxide as the oxidant, the combination of palladium acetate and hydroquinone forms an efficient catalyst system, which does not require other cocatalysts. Using t-butylhydroperoxide as the oxidant, it is possible to react a series of different carboxylates with alkenes in methylene chloride solution. For instance, (5)-0-acetylmandelic acid was reacted with cyclohexene to give the addition product with a modest chiral induction (de ca. 20%). Also, intramolecular cyclization could be achieved for example, 2-cyclopenten-l-acetic acid gave mainly the allylic lactone in good yield, accompanied by a small amount of the double bond isomer (Scheme 9). 

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