3- Methyl-2,4-pentanedione, from

Methyl-2,4-pentanedione, from 2-bu-tanone and acetic anhydride, 51,... 

Tanino, H., Takakura. H., Kakoi, H.. Okada. K.. and Inoue, S. (1996) (S)-2-Methyl-1.5-bis(l,3-dimethyl-6-lumazinyl)-1.5-pentanedione from the marine polychaete Odontosyllis undecimdonta. Heterocydes, 42, 125-128. 

Using different mono- and diketones in acetic acid (at room temperature) afforded the following products from benzophenone, 2,2-diphenyl-2//-imid-azo[4,5-/]quinoline from dibenzylketone, the 2-benzyl-imidazo[4,5-/]quino-line and from 2,4-pentanedione, 2-methyl-imidazo[4,5-/]quinoline. Cyclohexanone under reflux gave 2-n-pentyl-, whereas at room temperature it afforded the. s pira[cyclohexane-l,2 ]-(2//)-imidazo[4,5-/]quinoline 108 (R R =(CFl2)5) (86UC527). 

Base catalysis. Calculate Gb and (3 from the following data for the base-catalyzed eno-lization of 3-methyl-2,4-pentanedione 41... 

The conversions observed followed the sequence of reactivity known from batch experiments carried out in advance. For example, only 15% conversion was found for the less reactive reagent benzoylacetone in the micro reactor experiment, while 56% was determined when using the more reactive 2,4-pentanedione (batch syntheses 78% and 89%, respectively) [8]. Using the stopped-flow technique (2.5 s with field applied 5.0 s with field turned off) to enhance mixing, the conversions for both syntheses were increased to 34 and 95%, respectively. Using a further improved stopped-flow technique (5.0 s with field applied 10.0 s with field turned off), the conversion could be further enhanced to 100% for the benzoylacetone case. For the other two substrates, diethyl malonate and methyl vinyl ketone, similar trends were observed. 

Trimethyl phosphite (11.3 g, 0.091 mol) was added to a solution of 3-benzylidene-2,4-pentanedione (16.35 g, 0.091 mol) in dry methylene chloride. The solution was maintained under nitrogen for 24 h at 20°C and for an additional 5 h at 40°C. After this time, the solvent was evaporated, and the residue was dissolved in hexane. These actions were performed in the absence of moisture. The clear hexane solution was seeded with a crystal of the pure crystalline product (obtained by crystallization from hexane by standing for 2 weeks at 0°C), and after 8 h at 0°C the crystals precipitated yielding pure 2,2,2-tri-methoxy-3-phenyl-4-acetyl-5-methyl-A4-oxaphospholene (25.12 g, 88.4%) of mp 48-51°C. 

Diiron enneacarbonyl, 50, 2J Diketones, from diazoketones and organoboranes, 53/ 82 3-DIKETONES FROM METHYL ALKYL KETONES 3-n-BUTYL-2,4-PENTANEDIONE, 51, 90 2,6-Dimethoxybenzaldehyde, by reduction of 2,6-dime thoxy-benzonitrile with Raney nickel alloy in formic acid,... 

Figure 1 Transfer chemical potentials for selected iron complexes from water into aqueous methanol (on the molar scale, at 298 K). Ligand abbreviations not appearing in the list at the end of this chapter are acac = acetylacetonate (2,4-pentanedionate) dmpp = l,2-dimethyl-3-hydroxy-4-pyridinonate, the anion from (24) malt = maltolate (2-methyl-3-hydroxy-4-pyranonate, the anion from (233)).

P-DIKETONES FROM METHYL ALKYL KETONES 3-w-BUTYL-2,4-PENTANEDIONE... 

DIKETONES from methyl alkyl KETONES 3-n-BUTYL-2,4-PENTANEDIONE, 51, 90... 

Tellurium dipropionylmethane (2 6-Dimethylcyclotelluro-pentanedione) (Formula II), obtained from the dichloride by bisulphite reduction, crystallises from methyl alcohol, benzene or aqueous ethyl alcohol as well-defined golden-yellow needles, M.pt. 151° C. with slight decomposition. Under diminished pressure it sublimes at 110° C. as slender needles, which slowly pass at this temperature into compact prisms. It readily dissolves in organic solvents, except light petroleum in water it is sparingly soluble, the solution giving no enolic reactions. 

Propargyl alcohol, 2,4-pentanedione and 3-methyl-2,4-pentanedione were purchased from Aldrich Chemical Company, Inc., and were used without further purification. Dichloromethane and triethylamine were distilled from calcium hydride prior to use. Methanol was dried and distilled from magnesium-iodine. 

The preparation of highly functionalization selenophenes has been accomplished utilizing a three-component condensation reaction involving ketene dithioacetals, sodium selenide, and an activated carbonyl component (Scheme 13) <2003SL855, 2004S451, 2005PS939>. Ketene dithioacetal 122 was prepared from 2,4-pentanedione by condensation with carbon disulfide followed by methylation. Treatment of compound 122 with sodium selenide and ethyl bromoacetate gave selenophene 123 in modest yield. 

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