Dicarbonyl anhydride

Potential 2,5-dihydroxy compounds (185) exist in the dicarbonyl forms (186). Succinic anhydride (186 Z = O) on silylation is converted into 2,5-bis(trimethylsilyloxy)furan (187) the latter compound readily participates in Diels-Alder addition reactions (80TL3423). Reaction of thiosuccinic anhydride (186 Z = S) with the triphenylphosphorane Et02CH=PPh3 gives a product which exists in the aromatic form (188) (75LA1967). 

The chloride of triflic acid (trifluoromethanesulfonyl chloride) is an effective sulfonylating agent Like triflic anhydride, it usually reacts with alcohols and other nucleophiles with the formation of the corresponding derivatives of tnflic acid [69] However, in some reactions, it acts as a chlorinating reagent [98] The reactions of tnfluoromethanesulfonyl chloride with 1,3-dicarbonyl compounds or some carboxylic esters in the presence of a base result m the formation of chlonnated products in high yields (equation 49)... 

Triafulvenes derived from cyclic 0-dicarbonyl systems like 84/85ia 861S and S779 are conveniently prepared from cation 75 by the DIPEA method and in some cases (5780,81), 8862 8983 ) from diphenyl cyclopropenone by condensation in acetic anhydride. 

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

Aminocarbazoles form 3-(pyrrol-I-yl)carbazoles with 1,4-dicarbonyl compounds." It is interesting that Vilsmeier formylation of one such pyrrolylcarbazole (211 R = H), in which attack could occur at a pyrrole P-position or on the unsubstituted carbazole ring at C-6, substitution took the former course, thus producing 211 (R = CHO). " 3-Aminocarbazole gave an imide with maleic anhydride. ... 

It is not customary to attempt the isolation of ketone or aldehyde intermediates (121) the formula serves merely as a reminder that once hydrolysis of the protecting enol ether or acetal occurs, the same type of structure is formed from any given dicarbonyl compound. Cyclization has been carried out in refluxing ethanolic picric acid or acetic anhydride with a few drops of sulfuric acid, but Hansen and Amstutz (63JOC393) offered excellent theoretical reasons for avoiding an excess of acid, and reported that best results (Table 3) can be obtained by refluxing the dry hydrobromide in acetic anhydride containing no sulfuric acid. 

The diazaboroloimidazoles 195 have been formed in modest yields by reaction between 1,2-dicarbonyl compounds, amidine salts 196 and guanidine carbonate salt, and diphenylboronic anhydride <1988CB1865>. A parallel reaction... 

Furo[3,4-0]phthalazines (337, R = H, pj isv.isva j,ggjj obtained from the dicarbonyl compounds 336 (R = H,Ph). The phthalazine 337 (R = Ph) crystallizes as fine violet needles which fluoresce red in solution with maleic anhydride a Diels-Alder adduct is obtained in 99% yield. 

Compared to ozonation of alkenes, much less is known about the ozonation of alkynes,710 which yields 1,2-dicarbonyl compounds, carboxylic acids, and anhydrides. 1,2,3-Trioxolene (91), analogous to 74 in alkene ozonation mechanism (Scheme 9.14), and zwitterionic intermediates (92) were formulated on the basis of IR studies and trapping experiments ... 

The dicarbonyl [12539-66-1] available from 1,10-(N2)2B10H8 is another important species because of the scope ofits chemistry. Carbonyls of P 12 -12] can be formed from CO and the conjugate acid of [B12H12]2 . The B10- and B12-carbonyls exhibit very similar reactivity (99). The carbonyls can be considered anhydrides of carboxylic acids and accordingly react with alcohols and amines-to give esters and amides ... 

H-1,4-Benzodioxepin-ones and -diones have been prepared (72HC(26)319, p. 339) sodium salicylate and 2-chloroethanol give (385) (75BSF(2)277) and the methyl ester of 2-acetyl-6-chloro-3,5-dimethoxy-phenoxyacetic acid with hydrochloric acid gives (386). The dicarbonyl compound (387) is prepared by heating 2-carboxy-5,6-dimethoxyphenoxyacetic acid in acetic anhydride. Dicarbonyl compound (388) is prepared from chloroacetylsalicylic acid. 

From the synthetic viewpoint, a particularly interesting trifluoroacetylation reaction of simple vinyl ethers was reported first by Hojo et al in 1976 [73] The scope and limitation of this particular reaction were elaborated intensively, the reaction proved to be of general applicability with practically no restrictions on substituents of the vinyl ether moiety 9] (equation 34) This general validity is particularly beneficial because a trifluoroacetylated vinyl ether is the synthetic equivalent of a specifically protected tnfluoromethyl-substituted 1,3-dicarbonyl compound 19], thus the reaction provides access to a broad spectrum of variously substituted synthetic building blocks with selective reactivities on each carbon acceptor (a) and donor (d) center (equation 35) Obviously, such building blocks can react as heterodiene systems m cycloaddition reactions [< 74] or can be treated with a wide variety ot 1,2 or 1 3-dinucleophihc species to give any desired tnfluoromethyl-substituted carbocychc or heterocyclic system [8 75] Treatment of simple vinyl ethers with an excess of trifluoroacetic anhydride at elevated temperature leads to doubly acylated products [76] Comparable acylation reactions occur with vinyl thioethers [73], and the mesoiomc l,3-oxathiol-4-ones show, at least in a formal sense, similar behavior [77] (equation 36)... 

Unsaturated 1,4-Dicarbonyl Reaction. Bandow et al. [144,145] observed the formation of maleic anhydride from benzene, toluene, and o-xylene possibly arising from the HO-initiated oxidation of the expected 1,4-dicarbonyl (CHO)CH=CH(CHO), i.e ... 

In the case of 2,5-dimethylfuran (51) the dicarbonyl compound is revealed by the disconnection of one carbon-oxygen bond ring construction is of type (44). The forward synthetic reaction is a cyclodehydration reaction effected by the action of acetic anhydride in the presence of zinc chloride (Expt 8.12). 

Dicarbonylation in aprotic solvents yields acid anhydrides. Fulgide (dimethylene-succinic anhydride derivative) 78 was obtained in 49% yield by the Pd(0)-catalysed dicarbonylation of 2,5-dimethyl-3-hexyne-2,5-diol (76) via 77 in benzene [6], The fulgide-forming reaction proceeds more smoothyl using Pd(OAc)2 as the catalyst in the presence of iodine (Pd l2 = 1 1) instead of hydrochloric acid [18]. 

Using a chiral 4-dimethylaminopyridine-ferrocenyl catalyst, acyclic silyl ketene acetals react with anhydrides to furnish 1,3-dicarbonyl compounds containing allcarbon quaternary stereocentres in good yield and ee.144 Evidence for dual activation (anhydride -> acylpyridinium, and acetal -> enolate) is presented. 

The starting compound 251 was reduced to 252 with sodium borohydride. The latter was heated under reflux in 6% sulfuric acid in methanol to afford compound 253. Treatment of the latter with maleic anhydride at 170° for 3 hr afforded compound 254. Bisdecarboxylation of 254 with dicarbonyl bistriphenylphosphinenickel in anhydrous diglyme under nitrogen at reflux temperature for 6 hr afforded the olefin 255 in 69% yield (171). The latter was reduced with lithium aluminium hydride to the primary alcohol 256, which was oxidized to the aldehyde 257 with Ar,A -dicyclohexylcarbodiimide, dimethyl sulfoxide and pyridine in dry benzene. Treatment of the aldehyde 257 with an excess of the Grignard reagent prepared from l-bromo-3-benzyloxybutane afforded a mixture of diastereoisomers represented by the structure 258. 

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