Dicarbonyl Compounds and their Derivatives

The use of pyridinlum chlorochromate as a reagent for the oxidation of alcohols to aldehydes and ketones (including carbohydrate ketones) has been reviewed, and a review in Japanese on nucleophilic additions to carbohydrate-derived ketones has been 2 

A quantitative synthesis of D-gluco-hexodialdose from D-glucuronlc acid Involves dlethylborane reduction of a-D-gluco-furanuronic acid 1,2 3,5 bis-ethylboronate. 

5-ketone (3) was obtained similarly from 1,2-0-isopropylidene-3,5,6-0 -methylldyne-a-D-glucofuranose. Oxidation of methyl 3- - 

References to the use of 3- and 4-ulosldes In the synthesis of deoxy- and branched-chain sugars are made in Chapters 11 and 13, respectively. Compounds (7)-(9) deactivate a bacteriophage, probably by generation of superoxide radicals which cause the ketones to undergo autoxldatlon. Sodium borohydride reduction of the disaccharide ketones (10) gives mainly D-allo-products with 

A new paper on 4 -methoxyadenosine is referred to In Chapter 19 such compounds are formally derivatives of D-erythro-pentos-4-ulose. 

This Chapter contains material relevant to dialdoses, aldosuloses, diuloses, and other dicarbonyl compounds and their derivatives. Unsaturated members of the series are referred to in Chapter 12. 

A further example of the complexity of the structures of derivatives of hydroxy-carbonyl carbohydrates is provided by l,6-anhydro-j3-D-crabmo-hexopyranos-3-ulose (8) which exists as the dimer (9) (see Vol. 5, p. 107), but gives the iso-propylidene compounds (10) (with a rearranged structure) as well as the diacetal 

method has been developed for the analysis of glucosone (j -arabino-hexos-2-ulose).  

6-Dideoxy-D-ery /zro-hexos-2-ulose has been found to occur in the cardeno-lide (10) of the Asdepiadaceae 

Bromination at C-5 of hexopyranose derivatives gives access to aldos-5-ulose derivatives (see Chapter 7). 

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Fluorine-Containing a-Dicarbonyl Compounds and Their Derivatives ... 

Electrochemical oxidation of thiophene derivatives in methanol at a Pt anode leads to different types of reactions depending upon the electrolytes used. With sodium meth-oxide, 2,5-dimethyl- and tetramethylthiophene [207] afforded 2,5-dimethoxy adducts as a mixture of cisitrcms isomers together with side-chain oxidation products. However, in the presence of sodium acetate, the latter become the main products. In methanol/sulfuric acid solutions, at a carbon anode, thiophene and derivatives [208] oxidations resulted in a ringopening reaction with loss of the sulfur atom, yielding y-dicarbonyl compounds and their... 

In a series of outstanding papers, Pinhey et al have shown that aryllead tricarboxylates react with soft nucleophiles to afford C-arylation products. These aryllead derivatives behave as aryl cation equivalents in reactions which involve a ligand coupling mechanism (see section 7.5).9 2 ju most cases, the reactions proceed in chloroform at 40-60 C in the presence of pyridine as a base with a ratio of substrate to organolead derivative to pyridine of 1 1 3. The substrates which easily undergo C-arylation include phenols, p-dicarbonyl compounds and their vinylogues, a-cyanoesters, a-hetero-substituted ketones, enamines and nitroalkanes. A very limited number of non-carbon nucleophiles has also been reported to react. 

In 1979, Chan reported the synthesis of oxabicyclo [3.2.1] and [3.3.1] compounds using the bis-silylated enol ethers of ketoesters 65, which cyclized with dicarbonyl compounds and their tetrahydrofuran or tetrahydropyran derivatives in the presence of titanium tetrachloride, Eq. 48 [77]. 

The discussion of this somewhat heterogeneous collection of free and substituted dicarbonyl carbohydrates will be divided into (a) dialdehyde compounds, (b) keto-aldehyde compoimds having free or substituted carbonyl groups, and (c) the diketo compounds. Each Section (except the last one, containing only a few members) will be divided into (a) an introduction consisting of a general discussion concerning formation and preparation, (b) a description of individual compounds, and (c) a discussion of properties and reactions. A short discussion on oxidized polysaccharides is included before the Tables of dicarbonyl carbohydrates and their derivatives. 

Trifluoroacetamidine (585) is most widely used for the principal synthesis of pyrimidines. Compound 585 can be prepared from ethyl trifluoroacetate by ammo-nolysis, followed by dehydration with P2O5 and reaction with ammonia (Scheme 124) [335,336]. Amidine 585 has been introduced into reaction with various p-dicarbonyl compounds and their synthetic equivalents (Table 27), including p-ketoesters (Entries 1-6), in particular p-ketopyruvates (Entry 3) and a-alkoxymethylene-p-ketoesters (Entries 4-6), p-enaminocarbonyl compounds (Entries 7-9), malonic acid derivatives (Entry 10), fluorinated p-diketones (Entry 11), vinamidinium salts (Entry 12), a,p-unsaturated nitriles with leaving group at p position (Entries 13-15) and other bis-electrophiles (Entries 16, 17). Usually, the reaction gives moderate yields of the target 2-CF3-pyrimidines (ca. 50 %). 

It should be noted that carbonyl compounds, more often aldehydes, are usual second reagent in both the groups. Other building-blocks in these multicomponent processes, leading to the formation of five-, six-, and seven-membered heterocycles, can be numerous acids and their derivatives, p-dicarbonyl compounds or other CH-acids, isocyanides, etc. At this, three-component reactions of ABC and ABB types [32] are the most typical for aminoazole, although some four-component ABCC processes were also published. 

Several mono, bis or tris chelates of Ni11, Cu1, Znn and CoIB have been isolated with ligands derived from thioseleno-/J-dicarbonyl derivatives of the general form (59) with X = CH or N, R = NHPh, R = Ph or R = Ph, R = NHPh. Uhlemann et al. have reported the isolation of such compounds and their characterization using ESCA techniques.237 A related bis chelate of Niu (59 with X = N, R = Ph and R = NEt2), which was characterized by electronic and mass spectroscopy, has been reported recently.238... 

The majority of syntheses of 4/7-pyrans derive from the ring closure of 1,5-dicarbonyl compounds or their equivalents, which is discussed in detail in the previous volumes <1984CHEC, 1996CHEC-II> and is also the subject of a recent review <2000CHE1007>. In this manner, 2,6-bis(silyl)-47/-pyrans 79 are synthesized by the cyclodehydration of their corresponding l,5-bis(silyl)pentane-l,5-diones in good yield (Equation 43) <2000S843>. 

Acylainino-4-acylimidazoles have been made from 3-amino-l,2,4-oxadiazoles and 1,3-dicarbonyl reagents (see Section 2.2.1 and Scheme 2.2.5). 4(5)-Acylimidazoles can be derived from 4-acylaininoisoxazoles (see Section 6.1.2 and Scheme 6.1.3). (See also the discussion in Section 2.2.1 on 4-acylimidazole synthesis.) 5-Acyl-l-arylimidazoles can be made from or-oxoketene-SJV-acetals and nitrosoaromatics (see Section 3.2 and Scheme 3.2.5), and 4-acyl-imidazoles by nitration of 1,3-dicarbonyl compounds in their enolic forms, reduction to iV-alkenylformamides and subsequent cyclization (see Section 3.2 and Scheme 3.2.4). Examples have also been isolated from reactions of 2-oximino-l,2,3-tricarbonyls and amines (see Section 4.1 and Scheme 4.1.7), from compounds such as 3-chloro-4,4-dimethoxy-2-butanone and 3,4-disubstituted 3-buten-2-ones (see Section 4.3 and Scheme 4.3.5), and by ultraviolet irradiation of 1-alkenyltetrazoles which bear an acyl group conjugated with the exocyclic double bond (see Section 6.1.2.3). 

Refluxing 2-acetylmesitylene with selenium dioxide in aqueous dioxane for 5 h yields 82.5% of mesitylglyoxal as a yellow oil [576], The reaction is applicable to acetophenones 520, 678, 1001, to deoxybenzoin, its homologues, and their derivatives 517, 5i8] and to cyclic ketones [50 ]. a-Dicarbonyl compounds are produced in good yields (equation 409). 

In addition to their reactions with trlmethylsilyl enol ethers, (propargyl1um)Co2(C0)g complexes react with a variety of other mild carbon nucleophiles including activated aromatic compounds, g-dicarbonyl compounds, other enol derivatives (enol acetates and ketones directly), allylsilanes, and alkyl- and alkynyl-aluminum reagents. These reactions provide a flexible means to introduce the synthetically versatile propargyl function. Key features of propargylations using these complexes are 1) ready... 

Most information on cyclocondensation reactions of ZV-aminoazoles is concerned with vicinal N.C-diaminoazoles. In most cases, reactions were carried out with various carbonyl-containing compounds carboxylic acids and their derivatives, aldehydes and ketones, 1,2- an 1,3-dicarbonyl compounds, etc. Depending on the structure of these synthons, cyclocondensations lead to the formation of five-, and six- or seven-membered heterocycles. 

The reactions of 2-amino-2-deoxyaldoses and 1-amino-l-deoxyketoses, and their A-alkyl and A -aryl derivatives, with /3-dicarbonyl compounds give pyrrole derivatives whose nature depends somewhat upon the experimental conditions used. Accounts of these reactions, and discussions of the structures and properties of the products, are given in this Section. The mechanisms are dealt with in Section IV. 

Thiadiazine 1,1-dioxides (389) have been synthesized by Ochoa s group and a comparative study of their physiochemical properties with that of pyrazoles 390 has been made371,372. Rough parallels are observed in the tautomeric equilibria of (389) and (390) with 13C chemical shifts and the reactivity of the 4-position while differences in their aromaticity have been observed. The 1,2,6-thiadiazine-1,1-dioxides 389 are prepared either by reaction of sulphamide or substituted sulphamides with 1,3-dicarbonyl compounds or their acetal derivatives or by AT-alkylation of the unsubstituted derivatives. 

Several 9-substituted tetrahydroxanthen-l-ones result from the asymmetric Bronsted acid-catalyzed addition of the in situ generated o-qui-none methides from hydroxyarylbenzyl alcohol derivatives, and their subsequent reaction with cyclohexane-1,3-diones (Scheme 71) (14AGE13258). Other examples arise from a one-pot three-component reaction of salicylaldehydes, cyclic 1,3-dicarbonyl compounds and thiols, in the presence of ammonium chloride in aqueous medium at room temperature (14S73). A one-pot pseudo-three-component reaction of arylg-lyoxals and 2-thiobarbituric acid gives 9-aroyl tetrahydroxanthene-type compounds (14AJC283). 

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