Ketone, nonenolizable

In a reaction related to the mixed Claisen condensation nonenolizable esters are used as acylatmg agents for ketone enolates Ketones (via their enolates) are converted to p keto esters by reaction with diethyl carbonate... 

Esters of nonenolizable monocarboxylic acids such as ethyl benzoate give p diketones on reaction with ketone enolates... 

On treatment with a strong base such as sodium hydride or sodium amide, dimethyl sulfoxide yields a proton to form the methylsulfinyl carbanion (dimsyl ion), a strongly basic reagent. Reaction of dimsyl ion with triphenylalkylphosphonium halides provides a convenient route to ylides (see Chapter 11, Section III), and with triphenylmethane the reagent affords a high concentration of triphenylmethyl carbanion. Of immediate interest, however, is the nucleophilic reaction of dimsyl ion with aldehydes, ketones, and particularly esters (//). The reaction of dimsyl ion with nonenolizable ketones and... 

The present synthesis10 consists of two simple steps, uses readily available and inexpensive starting materials, and produces pure material in high overall yield. It is based on two observations that nonenolizable ketones may be cleaved to carboxylic acids by potassium ferf-butoxide-water,2 and that aryl 2 chlorophenyl ketones may be cleaved with loss of the 2-chlorophenyl group to give only one of the two possible acids.11 Other compounds prepared by this route include carboxycyclopentadienyltriearbonylmanganese [Manganese, tricar-bonyl[(l, 2,3,4,5- )-l-carboxy-2,4-cyclopentadien-l-yl]-] (79%)10 and... 

Ordinary ketones are generally much more difficult to cleave than trihalo ketones or p-diketones, because the carbanion intermediates in these cases are more stable than simple carbanions. However, nonenolizable ketones can be cleaved by treatment with a 10 3 mixture of t-BuOK—H2O in an aprotic solvent such as ether, dimethyl sulfoxide, 1,2-dimethoxyethane (glyme), and so on, or with sohd t-BuOK in the absence of a solvent. When the reaction is applied to monosubstituted diaryl ketones, that aryl group preferentially cleaves that comes off as the more stable carbanion, except that aryl groups substituted in the ortho position are more readily cleaved than otherwise because of the steric effect (relief of stain). In certain cases, cyclic ketones can be cleaved by base treatment, even if they are enolizable. " OS VI, 625. See also OS VH, 297. 

A more highly oxidized indole relative is isatin (47). The ketonic carbonyl group is nonenolizable and has interesting properties. In strong acid it... 

Metalation of nonenolizable carbonyl groups.1 This lithium amide, which lacks -hydrogens, cannot reduce nonenolizable aldehydes or ketones but can metalate these substrates. Thus reaction of LTMP with trimethylacetaldehyde (1) evidently results in an acyllithium (a) as shown by formation of an acyloin (2, equation I). 

Electron-transfer initiation from other radical-anions, such as those formed by reaction of sodium with nonenolizable ketones, azomthines, nitriles, azo and azoxy compounds, has also been studied. In addition to radical-anions, initiation by electron transfer has been observed when one uses certain alkali metals in liquid ammonia. Polymerizations initiated by alkali metals in liquid ammonia proceed by two different mechanisms. In some systems, such as the polymerizations of styrene and methacrylonitrile by potassium, the initiation is due to amide ion formed in the system [Overberger et al., I960]. Such polymerizations are analogous to those initiated by alkali amides. Polymerization in other systems cannot be due to amide ion. Thus, polymerization of methacrylonitrile by lithium in liquid ammonia proceeds at a much faster rate than that initiated by lithium amide in liquid ammonia [Overberger et al., 1959]. The mechanism of polymerization is considered to involve the formation of a solvated electron ... 

Trifluoromethyl phenylsulfone is accessible from fluoroform and diphenyldisul-fide, and it has been proposed as a donor of CF3. However, the reaction must be performed in basic medium (f-BuOK) and is then limited to nonenolizable aldehydes and ketones. But it can also be used as a precursor of the Ruppert reagent. This latter... 

Acid derivatives that can be converted to amides include thiol acids RCOSH, thiol esters RCOSR,911 acyloxyboranes RCOB(OR )2,912 silicic esters (RCOO)4Si, 1,1,1-trihalo ketones RCOCX3,913 a-keto nitriles, acyl azides, and nonenolizable ketones (see the Haller-Bauer reaction 2-33). 

Cleavage of ketones with sodium amide is called the Haller-Bauer reaction.514 As with 2-45, which is exactly analogous, the reaction is usually applied only to nonenolizable ketones, most often to ketones of the form ArCOCR3, where the products R3CCONH2 are not easily attainable by other methods. However, many other ketones have been used, though benzophenone is virtually unaffected. It has been shown that the configuration of optically active R is retained.515 The NH2 loses its proton before the R is cleaved 516... 

Aldol condensation. Anhydrous lithium iodide (ca. 5 equivalents) promotes aldol condensation of ketones with enolizable or nonenolizable aldehydes. The intermediate aldol is usually not isolable, but can be intercepted by addition of ClSi(CH3)3 and N(C2H5)3. In this case Lil can be used in a catalytic amount. The salt cannot be replaced by LiBror LiCl or Nal. 

Alkyltrisidialkylamino)titanium derivatives, R Ti(NR2)3. ) These reagents are readily available by reaction of halotris(dialkylamino)titanium with organolithium or -magnesium compounds. The reagents, prepared in situ in ether, react with nonenolizable aldehydes to give tertiary amines (1), possibly via an iminium salt (equation I). With enolizable aldehydes and ketones, the reaction results in enamines after nonaqueous workup. 

Nonenolizable ketones and aldehydes add to disilenes affording the corresponding [2 + 2] adducts 207 [Eq. (98)] as shown in review OW.7... 

The opposite situation is given if two molecules fixed at the polymer should react. According to Scheme 4 a small amount of the chloromethyl groups are reacted with an enolizable acid the rest with an nonenolizable acid. Addition of a base results in the formation of only one ketone, without the use of a polymeric support a complex mixture results (Table 3) (56). 

In marked contrast to the reaction of the silaethene intermediates, R Si=CH2, with ketones at high temperature (90, 91), the reaction of all the silicon-carbon double-bonded intermediates generated from the arylpentamethyldisilanes with either enolizable or nonenolizable ketones yields 2-trimethylsilyl(alkoxydimethylsilyl)benzene derivatives (92). Neither silyl enol ethers to be expected from O—H addition of enol form of enolizable ketones to the silicon-carbon double bond nor products from a... 

The silicon-carbon double-bonded intermediates generated photo-chemically from a-alkenyldisilane derivatives react with both enolizable and nonenolizable ketones to give olefins (98). For instance, the photolysis of a-styrylpentamethyldisilane (49) in the presence of one molar equivalent of acetone gives l-trimethylsilyl-2-phenyl-3-methyl-2-butene in 13% yield as a single product. No silyl enol ether to be expected from the reaction of the intermediate with the enol form of acetone is observed. Similar irradiation of 49 with acetophenone affords (E)- and (Z)-l-trimeth-... 

Boron-Wittig reactions." The reaction of anions of Mes,BR with nonenolizable aldehydes or ketones results in an adduct that spontaneously eliminates MesiBOLi to give an alkene in good yield. 

The dianion reacts with enolizable and nonenolizable aldehydes and ketones to provide the adducts in —70-90% yield (equation 1). ... 

Uranium(VI) fluoride converts adamantanone into 2.2-difluoroadamantane in 41 % yield. With other nonenolizable ketones no reaction takes place. 

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