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Decarboxylation-carbonylation

Palladium-catalyzed (PdCl2(PPh3)2) decarboxylative carbonylation reactions for the formation of lactams are known to proceed under carbon monoxide at a pressure of 60 atmospheres. The scheme below highlights a new procedure utilizing a different Pd catalyst, where the formation of lactams 171 from oxazolidinones 172 takes place at atmospheric pressure <06S227>. [Pg.337]

The palladium-catalysed decarboxylative carbonylation of 5-vinyloxazolidin-2-ones 218 caused, unexpectedly, a ring enlargement process to 5-lactams 219 <00JA2944>. The conjugate addition of 4-phenyloxazolidin-2-one to a nitroalkene was used for the synthesis of diastereoisomers of dethiobiotin <00EJO3575>. Attempted deprotection of the O-TBDMS... [Pg.233]

Several examples of transition metal catalysis for the synthesis of piperidines appeared this year. Palladium catalyzed intramolecular urethane cyclization onto an unactivated allylic alcohol was described as the key step in the stereoselective synthesis of the azasugar 1-deoxymannojirimycin . A new synthetic entry into the 2-azabicyclo[3.3.1]nonane framework was accomplished through a palladium mediated intramolecular coupling of amine tethered vinyl halides and ketone enolates in moderate yields . A palladium catalyzed decarboxylative carbonylation of 5-vinyl... [Pg.253]

The Pd-catalyzed reaction of propargyl electrophiles with carbon monoxide is a convenient route to allenyl carboxylic acid derivatives. In 1986, Tsuji et al. reported the Pd-catalyzed decarboxylation-carbonylation of propargyl carbonates under a CO at-... [Pg.102]

The Pd-catalyzed reaction of 5-vinyl-l,3-oxazolidin-2-ones 260 at 65-70°C and 65 atm of CO in ethanol gave 5-lactams 263 in fairly good to high yields (Scheme 38).As Scheme 38 illustrates, this decarboxylative carbonylation reaction is likely to involve (i) the cleavage of the allylic C-O bond of 260 to form tr-allyl-Pd complex syn-2(A, (ii) isomerization to anti-2(A, (iii) decarboxylation forming 7r-allyl-Pd-amine complex 262, and (iv) CO insertion to 262 followed by aminolysis to yield 5-lactam 263. [Pg.542]

Decarboxylation-carbonylation fS,y-unsaturated esters. Allylic carbonates undergo decarboxylation-carbonylation in the presence of this palladium catalyst at 50° under 10 atms of CO to give /l,y-un saturated esters in 70-95% yield.1 Example ... [Pg.201]

Daunomycinone, 254, 255 Debenzylation, 532 Debromination, 276, 548, 599 Decarboalkoxylation, 301 Decarboraethoxynauclechine. 185 Decarbonylation, 393 Decarboxylation-carbonylation, 392 Dehydroamination, 502 Dehydroamino acids, 6-7 Dehydrocyanation, 173 Dehydrosulfiiration, 62 Dehydroxylation, 127 Dendrobatid toxins, 43 Dendrolasin, 419 Denitration, 547 Deoxoprosophylline, 315 11-Deoxyanthracycline, 113 11-Deoxydauomycinone, 85 Dcoxyfrenolicin, 357 14-Deoxymuristerone, 127... [Pg.333]

Oxazolidines can be converted into 3,6-dihydro-177-pyridin-2-ones in a new synthesis (Equation 191) <2000JA2944> involving a palladium-catalyzed decarboxylative carbonylation. [Pg.293]

Allene carboxylates have been synthesized from propargylic carbonates using a palladium-catalysed decarboxylation-carbonylation... [Pg.432]

In 2000, a palladium-catalyzed decarboxylative carbonylation of 5-vinyloxazolidin-2-ones was studied by Knight and coworkers [44]. By a palladium-catalyzed decarboxylative carbonylation process, 5-vinyloxazohdin-2-ones, which are prepared... [Pg.22]

Yamamoto and co-workers have reported the decarboxylation-carbonylation reaction of aUyl carbamates to afford /3,y-unsaturated amides (Scheme 57),... [Pg.120]

Further examples of this decarboxylative carbonylation reaction are shown in Scheme Note that no base is used in this process, because the reactive nucleophile, the alkoxide, is generated directly in situ. [Pg.705]

Tanner and Somfai have reported that 2-vinyl-Af-tosyl aziridines can be ring-expanded by CO insertion, in a stereospecific maimer (Scheme 48),whereas Bando and coworkers reported a stereospecific decarboxylative carbonylation of cyclic carbamates (Scheme 49). ... [Pg.719]

Derivatives of Y-hydroxyacetylenic acids, which are useful intermediates in the synthesis of butenolides, are prepared from propiolic acid and ester anions. Alk-2-ynoic and 2-allenic esters are prepared by the oxidation of 3,4-disubstituted 2-pyrazolin-5-ones with lead(iv) tetra-acetate in the absence and presence of BF3 respectively. Py-Unsaturated esters are produced in high yield by the palladium-catalysed decarboxylation-carbonylation of allylic carbonates. Magnesium enolates of esters react with nitriles to give (Z)-3-amino-alk-2-enoates. Enol lactones react with diethyl methoxycarbonylmethylphosphonate to give cyclic unsaturated keto-esters (Scheme 66). ... [Pg.124]

The role of the base is apparently primarily that of a proton remover from the reactive methylene group thus if B represents the base, reaction (i) gives the carbanion, which then combines with the positive carbon of the carbonyl group (reaction ii) the product regains a proton from the piperidinium ion, and then by loss of water followed by mono-decarboxylation of the malonic acid residue gives the final acid. [Pg.279]

By the ketonic hydrolysis of substituted acetoacetic esters this is brought about by the action of dilute alkali in the cold, followed by acidification and boiling. The free substituted acetoacetic acid is produced, which readily undergoes decarboxylation (since it has a carboxyl and a carbonyl group on the same carbon atom) to give a ketone, for example ... [Pg.335]

The phenylacetic acid derivative 469 is produced by the carbonylation of the aromatic aldehyde 468 having electron-donating groups[jl26]. The reaction proceeds at 110 C under 50-100 atm of CO with the catalytic system Pd-Ph3P-HCl. The reaction is explained by the successive dicarbonylation of the benzylic chlorides 470 and 471 formed in situ by the addition of HCl to aldehyde to form the malonate 472, followed by decarboxylation. As supporting evidence, mandelic acid is converted into phenylacetic acid under the same reaction conditions[327]. [Pg.192]

The compounds most frequently encountered m this reaction are (3 keto acids that is carboxylic acids m which the (3 carbon is a carbonyl function Decarboxylation of (3 keto acids leads to ketones... [Pg.818]

Section 19 17 11 Dicarboxylic acids (malonic acids) and p keto acids undergo thermal decarboxylation by a mechanism m which a p carbonyl group assists the departure of carbon dioxide... [Pg.824]

When both building block units are m place on the acyl carrier protein carbon-carbon bond formation occurs between the a carbon atom of the malonyl group and the carbonyl carbon of the acetyl group This is shown m step 1 of Figure 26 3 Carbon-carbon bond formation is accompanied by decarboxylation and produces a four carbon acetoacetyl (3 oxobutanoyl) group bound to acyl earner protein... [Pg.1075]

Reactions. The chemical properties of cyanoacetates ate quite similar to those of the malonates. The carbonyl activity of the ester function is increased by the cyano group s tendency to withdraw electrons. Therefore, amidation with ammonia [7664-41-7] to cyanoacetamide [107-91-5] (55) or with urea to cyanoacetylurea [448-98-2] (56) proceeds very easily. An interesting reaction of cyanoacetic acid is the Knoevenagel condensation with aldehydes followed by decarboxylation which leads to substituted acrylonitriles (57) such as (29), or with ketones followed by decarboxylation with a shift of the double bond to give P,y-unsaturated nitriles (58) such as (30) when cyclohexanone [108-94-1] is used. [Pg.470]

P-Peroxylactones undergo thermal decarboxylation to carbonyl compounds by the initial formation of a 1,5-diradical (238). a-Peroxylactones undergo similar decarboxylation, emitting light since the ketone is generated in the triplet excited state (85,239,240) ... [Pg.130]

PUtzing erReaction. Quinoline-4-carboxyhc acids are easily prepared by the condensation of isatin [91-56-5] (16) with carbonyl compounds (50). The products may be decarboxylated to the corresponding quinolines. The reaction of isatin with cycHc ketones has been reported, eg, the addition of cyclohexanone gives the tricycHc intermediate (17) [38186-54-8] which upon oxidation produces quinoline-2,3,4-tricarboxyhc acid [16880-83-4] (51). [Pg.391]

The first step of this reaction, decarboxylation of pyruvate and transfer of the acetyl group to lipoic acid, depends on accumulation of negative charge on the carbonyl carbon of pyruvate. This is facilitated by the quaternary nitrogen on the thiazolium group of thiamine pyrophosphate. As shown in (c), this cationic... [Pg.646]

The Pfitzinger reaction entails the synthesis of quinoline-4-carboxylic acids 2 via condensation of isatic acids formed from isatins 1 and a-methylene carbonyl compounds in the presence of strong aqueous bases. Subsequent decarboxylation can afford the corresponding quinolines. " ... [Pg.451]

Condensation of an appropriately substituted phenylacetic acid with phthalic anhydride in the presence of sodium acetate leads to aldol-like reaction of the methylene group on the acid with the carbonyl on the anhydride. Dehydration followed by decarboxylation of the intermediate affords the methylenephthal-ides (12). Treatment of the phthalides with base affords directly the indandiones, probably via an intermediate formally derived from the keto-acid anion (13). The first agent of this class to be introduced was phenindandione (14) this was followed by anisindandione (1S) and chlorindandione (16). ... [Pg.147]


See other pages where Decarboxylation-carbonylation is mentioned: [Pg.204]    [Pg.263]    [Pg.512]    [Pg.46]    [Pg.461]    [Pg.480]    [Pg.114]    [Pg.114]    [Pg.204]    [Pg.263]    [Pg.512]    [Pg.46]    [Pg.461]    [Pg.480]    [Pg.114]    [Pg.114]    [Pg.45]    [Pg.481]    [Pg.443]    [Pg.86]    [Pg.722]    [Pg.587]    [Pg.812]    [Pg.813]    [Pg.333]   


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Rearrangement decarboxylation-carbonylation

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