Lithium pentanoate

One-electron oxidation of carboxylate ions generates acyloxy radicals, which undergo decarboxylation. Such electron-transfer reactions can be effected by strong one-electron oxidants, such as Mn(HI), Ag(II), Ce(IV), and Pb(IV) These metal ions are also capable of oxidizing the radical intermediate, so the products are those expected from carbocations. The oxidative decarboxylation by Pb(IV) in the presence of halide salts leads to alkyl halides. For example, oxidation of pentanoic acid with lead tetraacetate in the presence of lithium chloride gives 1-chlorobutane in 71% yield ... 

Mori started with the early introduction of the chiral centre [298] in using (3-oxidation of pentanoic acid A by the yeast, Candida rugosa, IFO 0750 [299]. The obtained (R)-3-hydroxypentanoic acid B was transformed into C in a few conventional steps. The second building block was prepared from methyl 2-pentynoate D conjugate addition of lithium dimethyl cuprate yielded E, which was further converted into the frans-configured vinyl bromide F. Hydro-boration of C yielded G which upon Suzuki s palladium catalysed cross-coupling with F furnished 157 after treatment of the reaction product with hydrochloric acid followed by chromatographic purification. The synthesis of ent-157 used (S)-3-hydroxypentanoic acid. 

The same research group has recently reported that the oxidative homocoupling of chiral aroylacetic acid derivatives proceeds stereoselectively when the sodium enolate derived from 38 is oxidized with bromine (equation 21). Good stereoselectivity was also observed in the oxidative homo- and heterocoupUng reactions of the lithium eno-lates of chiral 3-phenylpropionamides with iodine, copper(II) pentanoate and ferrocenium hexafluorophosphate. ... 

The triphenylmethyl carbanion, the trityl anion, can be generated by the reaction of triphenylmethane with the very powerful base, n-butyllithium. The reaction generates the blood-red lithium triphenylmethide and butane. The triphenylmethyl anion reacts much as a Grignard reagent does. In the present experiment it reacts with carbon dioxide to give triphenylacetic acid after acidification. Avoid an excess of n-butyllithium on reaction with carbon dioxide, it gives the vile-smelling pentanoic acid. 

Reduction of carboxylic acids. Burgstahler et al. a few years ago reported briefly that carboxylic acids can be reduced to aldehydes by lithium and ethyl-amine however, the yields for the most part were low except in the case of fairly high molecular weight acids. Bedenbaugh et al.3 report that the reaction is actually of considerable value. They used methylamine rather than ethylamine and maintained a basic medium. Under these conditions an intermediate imine can be isolated. This intermediate is hydrolyzed rapidly by aqueous acids to an aldehyde or it can be reduced to the corresponding amine either catalytically or with lithium in methylamine. The conversions are illustrated for pentanoic acid as starting material. 

High regioselectivity has been observed for addition of silyl enol ethers to a,p-unsaturated aldehydes and ketones, promoted by lithium perchlorate in diethyl ether. Potassium enolates of acyclic y-alkoxy-a-methyl pentanoates can be alkylated with allylic and benzylic halides with high 2,3-syn selectivity. The results have been rationalized in terms of non-chelated (for potassium enolates) and chelated (for lithium enolates) transition states. 

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