Carbonyl compounds reagents

Carbonyl compound Reagent / conditions Product Yield Ref. 

Apart from the Takai method and titanium reagents such as 15, silyl reagents 16 and 17 frequently find application in the synthesis of vinylic silanes from carbonyl compounds. Reagent 16 can be utilized with aldehydes and non-enolizable ketones in a reaction analogous to the Peterson olefination Reagent 17 also reacts successfully with enolizable ketones.6... 

Enolized ketone Acceptor carbonyl compound Reagent Yield %) Threo erythro... 

For a given carbonyl compound (reagent) reacting with a series of carboxylate ions (substrates), the rate constant k is related to the dissociation constant AT), of the base by the equation... 

Reaction with Carboxylic Acid Derivatives. In addition to carbonyl compounds, reagent (1) also reacts with carboxylic acid derivatives. Thus lactones provide hydroxy allylsilanes (3) (eq 3). ... 

For the preparation of 2 4-dinitrophenylhydrazones, dissolve the carbonyl compound (say, 0-5 g.) in 5 ml. of ethanol and add the cal culated volume of the reagent. If a precipitate does not form immediately, dilute with a little water. Collect the derivative and recrystalhse it as above. 

Both aldehydes and ketones contain the carbonyl group, hence a general test for carbonyl compounds will Immediately characterise both classes of compounds. The preferred reagent is 2 4-dinilrophenylhydrazine, which gives sparingly soluble phenylhydrazones with carbonyl compounds ... 

Note that NaBH4 reduces aldehydes (and ketones) but not esters while L1A1H4 reduces just about all carbonyl compounds. Neither reagent reduces an isolated deuble bond. 

The anion B is just the enolate anion of a carbonyl compound, actually the same as A. So there is no need to use a Grignard reagent or any other synthetic equivalent in this reaction anion B itself can be the intermediate and we simply treat the aldehyde with mild base ... 

Most syntheses of nitrogen heterocycles involve substitution and/or condensation reactions of nitrogen nucleophiles with difunctional halides or carbonyl compounds. Common nitrogen reagents are ... 

Various organotin reagents react with acyl and aroyl halides under mild conditions without decarbonylation to give carbonyl compounds[390,39l]. Alkyl- or alkenyltin reagents react with acyl and aroyl chlorides to give ketones[548.733,734]. One example is the preparation of the a,/3-dnsaturated 7-keto esters 860 and 861, carried out under a CO atmosphere[735]. The reaction has been applied intramolecularly to the synthesis of the macrocyclic keto... 

The use of a reagent bearing a basic center or the addition of a base to the reaction mixture was recognized as necessary to prevent the acid-catalyzed elimination of the elements of water from the intermediates. Since the publication of this work, a number of similar intermediates have been isolated from thioamides and a-halogeno carbonyl compounds (608, 609, 619, 739, 754, 801), and as a result of kinetic studies, the exact mechanism of this reaction has been well established (739, 821). 

The type of alcohol produced depends on the carbonyl compound Substituents present on the carbonyl group of an aldehyde or ketone stay there—they become sub stituents on the carbon that bears the hydroxyl group m the product Thus as shown m Table 14 3 (following page) formaldehyde reacts with Grignard reagents to yield pri mary alcohols aldehydes yield secondary alcohols and ketones yield tertiary alcohols... 

Analyze the following structures so as to determine all the practical combinations of Gng nard reagent and carbonyl compound that will give nse to each... 

Sodium borohydride and lithium aluminum hydride react with carbonyl compounds in much the same way that Grignard reagents do except that they function as hydride donors rather than as carbanion sources Figure 15 2 outlines the general mechanism for the sodium borohydride reduction of an aldehyde or ketone (R2C=0) Two points are especially important about this process... 

The diminished rr electron density m the double bond makes a p unsaturated aide hydes and ketones less reactive than alkenes toward electrophilic addition Electrophilic reagents—bromine and peroxy acids for example—react more slowly with the carbon-carbon double bond of a p unsaturated carbonyl compounds than with simple alkenes... 

CONJUGATE ADDITION OF ORGANOCOPPER REAGENTS TO a,p-UNSATURATED CARBONYL COMPOUNDS... 

The principal synthetic application of lithium dialkylcuprate reagents IS their reaction with a 3 unsatu rated carbonyl compounds Al kylation of the 3 carbon occurs... 

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

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