Ketone-acids => 1,3-diketones

Periodic acid oxidation will also act on a-hydroxy aldehydes and ketones, a-diketones, a-keto aldehydes, and glyoxal. If the two neighboring hydroxyl groups are on an aromatic ring, the carbon-carbon bond is not cleave but the reactant is still oxidized. Thus, catechol is oxidized to the corresponding quinone. 

LiInH4 is increased by the introduction of phenyl group(s) LiPhInH3 and LiPh2InH2 readily reduce aldehydes, ketones, acid chlorides, and even esters to the corresponding alcohols. Hydroxy ketones and diketones are reduced with lithium indium hydride to give meso-diols selectively. a-Hydroxy ketones and a-diketones are reduced to meso-1,2-diols with high diastereoselectivities, whereas the selectivities of /3-hydroxyketones and /3-diketones are less satisfactory.365... 

Thallium trinitrate, TI(N03)3 3H20 (mp 102-105 C), oxidizes phenols and dihydroxy aromatic compounds to quinones [409, acetylenes to a-hydroxy ketones, a-diketones, or carboxylic acids 413] and methyl ketones to a-keto acids [414],... 

Oxidations of hydroxy ketones to diketones occur frequently in steroidal alcohols. If the alcoholic group, usually secondary, is remote enough from the keto group, its oxidation takes place independently and is achieved by the same reagents that are used for the oxidation of alcohols. A solution of chromium trioxide in aqueous sulfuric acid oxidizes 5-pregnen-3p-ol-20-one in acetone solution at room temperature within 2-5 min to 5-pregnen-3,20-dione in 90% yield [579]. Similarly, lip-hydroxytestosterone 17-acetate is transformed by chromium trioxide in 80% acetic acid at room temperature in 30 min into 11-ketotestosterone 17-acetate in 92% yield [807]. 

The benzoin condensation has recently been recognized as belonging to the general class of reactions that involve masked acyl anions as intermediates. For example, an aldehyde is converted into an addition product RCH(OX)Y, which renders the C—H acidic. Then under basic conditions, a masked acyl anion (see 1) can be formed and may react with an electrophilic component E. Decomposition of the product RCE(OX)Y should regenerate the carbonyl group with formation of RC(0)E. Intermediates such as (1) are us in the conversion of aldehydes into a-hydroxy ketones, a-diketones and 1,4-dicarbonyl compounds, proving to be a powerful strategy in the development of new synthetic methods. ... 

Phenyl hydrazine undergoes condensation with /3-diketones and /3-ketone-acid-esters with the formation of ring compounds contain- Ing nitrogen — the so-called pyrazoles and pyrazolones- The phenyl methyl pyrazolone formed from acetacetic ester and phenyl hydrazine is of importance ... 

Finally, the chlorides of dibasic adds react with the formation at diketones or ketonic acids ... 

Surface lipids of plants. The thick cuticle (Fig. 1-6) that covers the outer surfaces of green planfs consists largely of waxes and other lipids but also contains a complex polymeric matrix of cutin (stems and leaves) or suberin (roots and wound surfaces). Plant waxes commonly have C q - Cgg chains in both acid and alcohol components. Methyl branches are frequently present. A major function of the waxes is to inhibit evaporation of water and to protect the outer cell layer. In addition, the methyl branched components may inhibit enzymatic breakdown by microbes. Free fatty acids, free alcohols, aldehydes, ketones, p-diketones, and alkanes are also present in plant surface waxes. Chain lengths are usually C20 -Hydrocarbon formation can occur in other parts of a plant as well as in the cuticle. Thus, normal heptane constitutes up to 98% of the volatile portion of the turpentine of Finns jejfreyi. ... 

Natural waxes can consist of a wide range of different lipid classes, including esters of various kinds, hydrocarbons, ketones, hydroxy-ketones, p-diketones, aldehydes, acids and terpenes. With cmde mixtures of this kind, it is usually necessary to react them with diazomethane to methylate free carboxyl groups, to acetylate (or to prepare TMS... 

Excluding consideration of a multitude of representatives of solvent extraction classes (water-insoluble alcohols, ethers, acids, esters, ketones and diketones) that have been examined and found to be inadequate in some respect or another, it is the intent here to focus upon only a few representatives of just three classes of extractants (1) neutral phosphorous agents (2) monoacidic orthophosphate and phosphonate esters and (3) primary, secondary, tertiary and quaternary ammonium ion species. 

Carboxylic acids and methyl ketones from -diketones... 

This synthesis of the pyrrole ring system, due to Knorr, consists in the condensation of an a-aminoketone with a 1,3-diketone or the ester of a p-keto-acid, a-Aminoketones are unstable in the free state, readily undergoing self-condensation consequently they must be prepared, by the reduction of an a-nitroso (or oximino) ketone, in the presence of the 1,3-diketone or p-ketoester, to ensure rapid interaction. 

A ketone having an a-hydrogen atom may be acylated with an eater or an acid anhydride to form a p diketone ... 

A mixture of an acid anhydride and a ketone is saturated with boron trifluoride this is followed by treatment with aqueous sodium acetate. The quantity of boron trifluoride absorbed usually amounts to 100 mol per cent, (based on total mola of ketone and anhydride). Catalytic amounts of the reagent do not give satisfactory results. This is in line with the observation that the p diketone is produced in the reaction mixture as the boron difluoride complex, some of which have been isolated. A reasonable mechanism of the reaction postulates the conversion of the anhydride into a carbonium ion, such as (I) the ketone into an enol type of complex, such as (II) followed by condensation of (I) and (II) to yield the boron difluoride complex of the p diketone (III) ... 

The polyhydric alcohols of Solubility Group II are liquids of relatively high boiling point and may be detected inter alia by the reactions already described for Alcohols (see 6). Compounds containing two hydroxyl groups attached to adjacent carbon atoms (1 2-glyeols), a-hydroxy aldehydes and ketones, and 1 2-diketones may be identified by the periodic acid test, given in reaction 9. 

Suggestions as to the methods for identifying the above classes of compounds will be found under Class Reactiona in Section XI,7. Some fimther remarks upon enolic compounds (see Table IV,1I4A) may be made here. Enols may be divided into (a) p-keto esters and (b) 1 3-diketones. With 5 per cent, sodium hydroxide solution, a p-keto ester yields the salt of the corresponding acid, which when heated with dilute hydrochloric acid is decarboxylated to a ketone ... 

A 1 3-diketone, under similar conditions, affords a ketone and the salt of an acid ... 

The most commonly used protected derivatives of aldehydes and ketones are 1,3-dioxolanes and 1,3-oxathiolanes. They are obtained from the carbonyl compounds and 1,2-ethanediol or 2-mercaptoethanol, respectively, in aprotic solvents and in the presence of catalysts, e.g. BF, (L.F. Fieser, 1954 G.E. Wilson, Jr., 1968), and water scavengers, e.g. orthoesters (P. Doyle. 1965). Acid-catalyzed exchange dioxolanation with dioxolanes of low boiling ketones, e.g. acetone, which are distilled during the reaction, can also be applied (H. J. Dauben, Jr., 1954). Selective monoketalization of diketones is often used with good success (C. Mercier, 1973). Even from diketones with two keto groups of very similar reactivity monoketals may be obtained by repeated acid-catalyzed equilibration (W.S. Johnson, 1962 A.G. Hortmann, 1969). Most aldehydes are easily converted into acetals. The ketalization of ketones is more difficult for sterical reasons and often requires long reaction times at elevated temperatures. a, -Unsaturated ketones react more slowly than saturated ketones. 2-Mercaptoethanol is more reactive than 1,2-ethanediol (J. Romo, 1951 C. Djerassi, 1952 G.E. Wilson, Jr., 1968). 

Active methylene or methine compounds, to which two EWGs such as carbonyl, alko.xycarbonyl, formyl, cyano, nitro, and sulfonyl groups are attached, react with butadiene smoothly and their acidic hydrogens are displaced with the 2,7-octadienyl group to give mono- and disubstituted compounds[59]. 3-Substituted 1,7-octadienes are obtained as minor products. The reaction is earned out with a /3-keto ester, /9-diketone, malonate, Q-formyl ketones, a-cyano and Q-nitro esters, cya noacetamide, and phenylsulfonylacetate. Di(octadienyl)malonate (61) obtained by this reaction is converted into an... 

In practice this reaction is difficult to carry out with simple aldehydes and ketones because aldol condensation competes with alkylation Furthermore it is not always possi ble to limit the reaction to the introduction of a single alkyl group The most successful alkylation procedures use p diketones as starting materials Because they are relatively acidic p diketones can be converted quantitatively to their enolate ions by weak bases and do not self condense Ideally the alkyl halide should be a methyl or primary alkyl halide... 

Enolization (Sections 18 4 through 18 6) Aldehydes and ke tones having at least one a hydro gen exist in equilibrium with their enol forms The rate at which equilibrium is achieved is in creased by acidic or basic cata lysts The enol content of simple aldehydes and ketones is quite small p diketones however are extensively enolized... 

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