Aldehydes, Ketones and Ketenes

Pregaglia,G.F., Binaghi.M. Ionic polymerization of aldehydes, ketones, and ketenes. In Ketley,A.D. (Ed.) The Stereochemistry of Macromolecules, Vol. 2 New York Marcel Dekker 1967. 

Heterounsaturated monomers that undergo coordination polymerisation or copolymerisation with other monomers can be divided into two classes monomers with a carbene-like structure such as isocyanides and carbon monoxide which are coordinated by n complex formation with the transition metal atom at the catalyst active site, and monomers such as isocyanates, aldehydes, ketones and ketenes which are coordinated via 5-bond formation with the metal atom at the catalyst active site. 

Insertion Reactions into Element-Halogen Bonds 11.6.4. Insertions of Aldehydes, Ketones, and Ketenes... 

The photochemical addition of azirines to the carbonyl group of aldehydes, ketones, and esters is also completely regiospecific (77H(6)143). Besides the formation of the isomeric oxazolines (50) from (39) and ethyl cyanoformate, there is also formed the imidazole (51) from addition to C=N in the expected regioselective manner. Thioesters lead to thiazolines (52), while isocyanates and ketenes produce heterocycles (53). 

Aldehydes, ketones, and quinones react with ketenes to give P-lactones, diphenylk-... 

Figure 5.6 Alcohols, aldehydes, ketones and acids 15, ethylene glycol 16, vinyl alcohol 17, acetaldehyde 18, formaldehyde 19, glyoxal 20, propionaldehyde 21, propionaldehyde 22, acetone 23, ketene 24, formic acid 25, acetic acid 26, methyl formate. (Reproduced from Guillemin et at. 2004 by permission of Elsevier)...

Aldehydes, ketones, and quinones react with ketenes to give p-lactones, diphenylketene being used most often. The reaction is catalyzed by Lewis acids, and without them most ketenes do not give adducts because the adducts decompose at the high temperatures necessary when no catalyst is used. When ketene was added to chloral Cl3CCHO in the presence of the chiral catalyst (+ )-quinidine, one enantiomer of the p-lactone was produced in 98% enantiomeric excess.777 Other di- and trihalo aldehydes and ketones also give the reaction enantioselectively, with somewhat lower ee values.778 Ketene adds to another molecule of itself ... 

Simple a,3-unsaturated aldehydes, ketones, and esters (R = C02Me H > alkyl, aryl OR equation l)i, 60 preferentially participate in LUMOdiene-controlled Diels-Alder reactions with electron-rich, strained, and selected simple alkene and alkyne dienophiles, - although the thermal reaction conditions required are relatively harsh (150-250 C) and the reactions are characterized by the competitive dimerization and polymerization of the 1-oxa-1,3-butadiene. Typical dienophiles have included enol ethers, thioenol ethers, alkynyl ethers, ketene acetals, enamines, ynamines, ketene aminals, and selected simple alkenes representative examples are detailed in Table 2. - The most extensively studied reaction in the series is the [4 + 2] cycloaddition reaction of a,3-unsaturated ketones with enol ethers and E)esimoni,... 

Table 2. Aldol reactions of ketene silyl acetals with aldehydes, ketones, and acetals.

The [4+2] cycloaddition reactions of linear and cyclic acylketenes proceed with double-bonded substrates, such as aldehydes, ketones and azomethines, with triple-bonded substrates, such as nitriles, and with heterocumulenes, such as ketenes, isocyanates, isothiocyanates and carbodiimides and numerous examples are reported 33. ... 

We begin with reactions of polar organometallics with aldehydes, ketones, and v/c-dicarbonyl compounds (a-oxoaldehydes, 1,2-diketones, a-oxocarboxamides, and a-oxocarboxylic acids). Next we focus on carboxamides, lithium carboxylates, carboxylic acid esters, and acyl chlorides. Finally we turn to ketenes, (thio)isocyanates, and carbon dioxide, all featuring cumulated double bonds, and last but not least to carbon monoxide. 

Dithiolane Formation. 1,2-Ethanedithiol (1) condenses with aldehydes, ketones, and acetals to afford 1,3-dithiolanes, - useful for carbonyl protection (eqs 1 and 2). Stability, condensation selectivity, and conditions for carbonyl regeneration parallel those discussed for 1,3-Propanedithiol. Esters and lactones can be protected as ketene dithioacetals and/or dithioortholactones, resistant to nucleophilic attack, using the bis(dimethylalanyl) derivative of (1). ... 

Carbonyl Compounds. Cychc ketals and acetals (dioxolanes) are produced from reaction of propylene oxide with ketones and aldehydes, respectively. Suitable catalysts iaclude stannic chloride, quaternary ammonium salts, glycol sulphites, and molybdenum acetyl acetonate or naphthenate (89—91). Lactones come from Ph4Sbl-cataly2ed reaction with ketenes (92). 

Aromatic aldehydes and cyclic perfluoroketones are oxidized to a-hydroxy hydroperoxides or bis(a-hydroxy) peroxides, aliphatic ketones are converted to esters, and ketenes are converted to a-lactones... 

Silyl enol ethers and ketene acetals derived from ketones, aldehydes, esters and lactones are converted into the corresponding o/i-unsaturated derivatives on treatment with allyl carbonates in high yields in the catalytic presence of the palladium-bis(diphenylphosphino)ethane complex (32). A phosphinc-free catalyst gives higher selectivity in certain cases, such as those involving ketene acetals. Nitrile solvents, such as acetonitrile, are essential for success. 

Supplement 1941 1-161 Derivatives. Methyl alcohol, 273. Ethyl alcohol, 292. Ethyl ether, 314. Glycerol, 502. Carbonyl Compounds Aldehydes, Ketones, Ketencs and Derivatives. Formaldehyde, 558. Acetaldehyde, 635. Acetone, 635. Ketene, 724. Hydroxy-Carbonyl Compounds Aldehyde-Alcohols, Ketone-Alcohols, Monosaccharides and Derivatives. Glycolaldehyde, 817. Aldol, 824. Pentoses, 858. Hexoses, 878. 

Dialkyl(trimethylsilyl)phosphines undergo 1,4-addition to a,/3-unsaturated ketones and esters to give phosphine-substituted silyl enol ethers and silyl ketene acetals, respectively. A three-component coupling reaction of a silylphosphine, activated alkenes, and aldehydes in the presence of a catalytic amount of GsF affords an aldol product (Scheme 76).290 291... 

The cycloaddition of aldehydes and ketones with ketene under the influence of quinine or quinidine produce chiral 2-oxetanones [46,47]. Solvolytic cleavage of the oxetanone, derived from chloral, and further solvolysis of the trichloromethyl group leads to (5)- and (R)-malic acids with a 98% ee [46] (the chirality of the product depends on the configuration of the catalyst at C-8 and, unlike other alkaloid-induced reactions, it is apparently independent of the presence of the hydroxyl group). No attempts have been made to catalyse the reaction with chiral ammonium salts. 

It has now been found that further extension of this reaction to ketone acetals and a wide range of aldehydes and ketones is possible when catalytic amounts of zinc chloride are added to the reaction mixture. The catalyzed reaction generally proceeds at room temperature and usually gives good yields of 2,2-alkoxyoxetanes (equation 100). This appears to be the method of choice for such compounds, since it is highly regiospecific, whereas the photochemical addition of aldehydes or ketones to ketene acetals is not (77JOC3128). 

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