Intermolecular decarboxylative

The factor n is a statistical one, which is tiqity for the intermolecular decarboxylation of monobasic carboxylic acids but 2 for the dibasic acid (e.g. malonic acid). We use the subscripts 12 and 13 to refer to C18 and C respectively. 

Figure 7 shows an intercomparison of the experimental data on the C18 isotope effect in intermolecular decarboxylation reactions with theoretical calculations based on the simple model... 

Aliphatic aldehydes are also obtained with high selectivity. Selectivity is lower for primary aliphatic carboxylic acids because of a competing intermolecular decarboxylation reaction which results in ketone formation (Eq. 2) [16]. This ketonization activity of Zr02 was, substantially suppressed by addition of metal ions. 

Wang, C., Rakshit, S., Glorius, F. (2010). Palladium-catalyzed intermolecular decarboxylative couphng of 2-phenylbenzoic adds with alkynes via C-H and C-C bond activation. Journal of the American Chemical Society, 132, 14006-14008. 

Scheme 3.12 Intermolecular decarboxylative direct C-3 arylation of indoles with benzoic acids, as reported by Larrosa and coworkers [24].

A copper/A,A-diisopropyl-ethylamine (DIPEA)-catalyzed, aldehyde-induced intermolecular decarboxylative coupling reaction of proline and... 

Reactions of phosphonic acids and their derivatives A copper catalysed intermolecular, decarboxylative coupling reaction of natural a-amino acids (583) and phosphites or secondary phosphine oxides (584) with aldehydes (585), has been developed in the synthesis of unnatural amino acid derivatives (586) (Scheme 145). ... 

The utility of base catalyzed condensations of esters to give jS-ketoesters is well known. A straightforward example of this reaction is the intermolecular cyclization of diethyl succinate giving 2,5-dicarbethoxy-l,4-cyclohexanedione, which can in turn be easily decarboxylated to give 1,4-cyclohexanedione. 

The regio- and stereochemical outcome of the intermolecular 1,3-dipolar cycloaddition of an azomethine ylide generated by the decarboxylative condensation of an isatin with an a-amino acid was unambiguously determined by a single-crystal X-ray study of the spirocyclic heterocycle 49 (R1 =4-Br, R2 = H, X = CH2) <1998TL2235>. 

An intermolecular addition on phthalimides employing heteroatom-substituted carboxylates was reported by the same group. In that study, a-thioalkyl-and a-oxoalkyl-substituted carboxylates were decarboxylated in the presence of... 

Considerable use has also been made of allyl carbonates as substrates for the allylation of Pd enolates.9 The reaction of Pd° complexes with allyl enol carbonates119,120 proceeds by initial oxidative addition into the allylic C—O bond of the carbonate followed by decarboxylation, yielding an allylpalladium enolate, which subsequently produces Pd° and the allylated ketone (equation 22). In like fashion, except now in an intermolecular sense, allyl carbonates have been found to allylate enol silyl ethers (equation 23),121 enol acetates (with MeOSnBu3 as cocatalyst) (equation 24),122 ketene silyl acetals (equation 25)123 and anions a to nitro, cyano, sulfonyl and keto groups.115,124 In these cases, the alkoxy moiety liberated from the carbonate on decarboxylation serves as the key reagent in generating the Pd enolate. 

The mechanisms proposed for these reactions are all quite analogous, and only the intramolecular cases will be considered in detail (Scheme 5). Oxidative addition by Pd° into the allylic C—O bond of the allyl 0-ketocaiboxylate produces an allylpalladium caxboxylate. This species then undergoes decarboxylation to yield an allylpalladium enolate (oxa-ir-allyl), which subsequently eliminates a 0-H to form the enone and provide an allyl-Pd-H. Reductive elimination from the allyl-Pd-H yields propene and returns Pd to its zero oxidation state. A similar mechanism can be imagined for the alkenyl allylcarbonate. Oxidative addition by the Pd° forms an allylpalladium carbonate, which decarboxylates again to give an allylpalladium enolate (oxa-ir-allyl). 0-Hydride elimination and reductive elimination complete the process. The intermolecular cases derive the same allylpalladium enolate intermediates, only now as the result of bimolecular processes. 

Since the decarboxylation of 161 to 162 proceeds in a poor yield, it was suggested that formation of 162 in benzene occurs directly from 2-benzopyrylium salts 62 through primary nucleophilic attack by amine in position 3. In this case, an enamine fragment of pyruvic acid appears in the ring-opened intermediate 163, which undergoes easy decarboxylation (82TL459). The vinylic carbanion 164, formed by the loss of carbon dioxide, captures a proton by intra- or intermolecular process, then hetero-cyclization takes place. 

The C8 aldehyde ester may be produced by cleavage of the 9-hydroperoxide of ethyl llnoleate followed by terminal hydroperoxidation. Further oxidation would produce the corresponding dicarboxylic acid which upon decarboxylation would give rise to ethyl heptanoate. The 8-alkoxy radical may also decompose to give the C7 alkyl radical, which would yield ethyl heptanoate or form a terminal hydroperoxide, and so on. Polymerization, both intra- and intermolecular, is also a major reaction in high temperature oxidation. Combination of alkyl, alkoxy, and peroxy radicals yields a variety of dimeric and polymeric compounds with C-O-C or C-O-O-C crosslinks. 

Dealkylation of tertiary amines with dibenzoyl peroxide, 44, 74 Decarboxylation, intermolecular, of isocyanates to carbodiimides, 43,32 Decker synthesis of amines, 44, 7t, 75 Dehalogenation of l,l,2-trichloro-2,3,3-trifluorocydobutane, 42,45 Dehydration, of formamides with phosphorus oxychloride to isocy-anides, 41, 13, 101 of 4- 2-hydroxyethyl)piperidine to quinuclidine, 44, 90 Dehydrohalogenation of 2-chloroallyl-amines to propargylamines, 44,55 Delepine reaction, to prepare 2-bromo-allylamine, 43, 6 Deoxyanisoin, 40,16 Deoxybenzoin, 40, IT Deoxypiperoin, 40, IT Deaylamine, 41, 8T... 

In contrast to intramolecular cyclizations, the intermolecular addition of O-centered radicals to ti systems as initiating step in complex radical cyclization cascades has only recently attracted considerable attention. The reason for the low number of papers published on O radical addition to alkenes and alkynes could originate from the perception that O-centered radicals, such as alkoxyl radicals, RO, or acyloxyl radicals, RC(0)0", may not react with 7t systems through addition at rates that are competitive to other pathways, for example, allylic hydrogen abstraction and p-fragmentation in the case of RO" or decarboxylation in the case of RC(0)0" (Scheme 2.9). 

Polyfluoroalk-2-ynoic acids 7 readily undergo an intermolecular-intrarnolecular Michael addition reaction with a variety of bifunctional azanucleophiles and o-phenylenediamine. to give the corresponding carboxylated and/or decarboxylated 2-(polyfluoroalkyl)imidazolidine (e. g, 8 and 9. respectively), thiazolidine, and oxazolidine derivatives in moderate to good yields. The products formed depend strongly on the reaction conditions employed. For example, the decarboxylated derivative 9 is only formed under reflux conditions. ... 

Synthetic complexes modeling a-keto carboxylate-dependent enzymes have played a key role in furthering our understanding of these enzymes. Several [Fe (L)(a -keto acid)] complexes have been reported as functional models using tetradentate and tridentate ligands. All of the model complexes that react with O2 afford quantitative yields of the decarboxylated a-keto acid, but in only two cases was the active oxidant trapped. Intermolecular olefin epoxidation has been observed in the case of [Fe (Tp )(BF)j complex. This complex reacts with O2 to form a species capable of stereospecific oxidation of cA-stilbene to its oxide as the product. However trans -stilbene is not epoxidized, suggesting that the active oxidant is capable of steric discrimination. 

Nitrocoumarins underwent intermolecular Diels-Alder reaction with substituted dienes, followed by sequential hydrolysis / decarboxylation / Nef reaction / cyclodehydration to afford dihydrodibenzo[f>,. 

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