Condensation with acetonylaceton

There are a few examples of the formation of indolizines from pyrroles. Thus pyrrole condenses with acetonylacetone in the presence of zinc acetate to give 5,8-dimethylindolizine (74) as the major product.87,88 3,4-Diethylpyrrole similarly gives 75.89 This same compound undergoes self-condensation in the presence of zinc acetate to give 76 in 24% yield.89 In another example tetramethine compounds (77) obtained from... 

N-Amimpyrroles The reagent condenses with acetonylacetone in hot acetic acid to give N-phthalimido-2,S-cliinethylpynrole (2)i which on reaction with hydrazine is split to phthalhydrazide (3) and N-amino-2,5-dimethylpyrrole (4),... 

In a 250 ml. conical flask, fitted with an air condenser of wide bore, place 50 g. (51 -5 ml.) of acetonylacetone (see Section V,9, Note 2) and 100 g. of ammonium carbonate (lump form). Heat the mixture in an oil bath at 100° until effervescence stops (60-90 minutes) some ammonium carbonate (or carbamate) sublimes into the condenser and this must be pushed back into the reaction mixture by means of a stout glass rod. Replace the air condenser by a Liebig s condenser with wide bore inner tube and reflux the mixture gently (bath temperature, 115°) for a further 30 minutes dissolve the solid which has sublimed into the condenser in about 5 ml. of hot water and return the solution to the reaction mixture. 

More recently, Russian workers have shown that 1-alkyl-3,6-dimethyl-1,4-dihydropyridazines (30) are produced in the condensation of acetonylacetone with alkyl hydrazines.81... 

The single example of the preparation of 1,2-dihydropyridazines (34) was reported by Zelenin and Dumpis,86 namely, the condensation of 1,2-dialkylhydrazines with acetonylacetone [Eq. (4)]. 

Bis-/3-di ketones 65 containing perfluoroalkyl groups are obtained by condensation of acetonylacetone with perfluorocarboxylic esters in the presence of lithium methoxide (95IZV2289, 98ZOR371) (Scheme 72). 

Concerning the synthesis of iV-aminopyrroles (52) Epton [276] has reported that the condensations of acetonylacetone and 2,5-diethoxytetrahydrofuran (succindialdehyde source) with A -aminophthalimide are superior to earlier methods where the partly-protected benzyloxycarbonyl- [277] and toluene-sulphony 1-hydrazines [278] were employed. Apparently this method fails with other 1,4-diketones, possibly due to steric effects [279]. 

With 1,4-dicarbonyl compounds, yet another type of reaction follows the initial condensation. Thus 2,4-dimethylpyrrole, heated with acetonylacetone and zinc acetate in acetic acid, gives 1,3,5,8-tetramethylindolizine (34). However, from pyrrole and acetylacetone the product is 4,7-dimethylindole, and other pyrroles with unsubstituted 2- and 3-positions similarly give derivatives of 4,7-dimethylindoleii . 

To 125 g. of finely powdered phosphorus sulphide (1) contained in a 500 ml. round-bottomed flask fitted with a reflux condenser, add 60 g. (62 ml.) of redistilled acetonylacetone (2). Heat cautiously at first until... 

Acetonylacetone is available commercially as a by-product of the manufacture of acetic acid from acetylene. It may be prepared by condensation of chloroacetone with ethyl sodioacetoacetate the resulting ethyl acetonylacetoacetate when heated with water under pressure at 160° undergoes ketonic scission to give acetonylacetone. 

Perumal investigated a novel variation that involved the combination of a Vilsmeier reaction with a Paal-Knorr condensation. Reaction of 3-benzoylpropionic acid (87) under Vilsmeier conditions furnished chloroformylfuran 88 in 75% yield, while reaction of acetonylacetone (89) provided formylfuran 90 in 60% yield." ... 

Condensation of 1,3-diketones with hydrazines or hydroxyamines was conducted in a microflow system to give pyrazoles and isoxazoles in good yields [22]. High-throughput synthesis of pyrrole by the Paal-Knorr condensation of ethanolamine and acetonylacetone was achieved using the CPC CYTOS Lab System [23], The running of the system for 165 min resulted in 714 g of the pyrrole (Scheme 4.14). 

In a 500-cc. Erlemneyer flask, fitted with an air-cooled reflux condenser of large bore (Note i), are placed 100 g. (0.88 mole) of acetonylacetone (Note 2) and 200 g. (1.75 moles) of ammonium carbonate, in lumps. The mixture is heated in an oil bath at ioo° imtil effervescence stops this requires sixty to ninety minutes. The air-cooled condenser is replaced by a water-cooled condenser of large bore, and the mixture is refluxed gently at 115° (bath temperatme) for thirty minutes longer (Notes i and 3). The mixture is cooled, and the upper, yellow layer of the pjuTole is separated (Note 4). The lower layer is extracted with 15 cc. of chloroform, which is added to the crude pyrrole. The whole is dried over anhydrous calcium chloride, in a tightly stoppered container which has been swept out with nitrogen beforehand. 

Procedure. The acetonylacetone and finely divided phtisplioriis trisulfide are heated cautiously until a spontaneous reaction l)egins to take place. After this reaction ceases the mixture is boiled under reflux for ten to fifteen minutes and then distilled until crystals begin to form in the condenser. The distillate is washed with aqueous sodium hydroxide and water, dried, and the 2,5-dimethylthiophene is distilled twice, b.p. 135.5-136°... 

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