3- methyl cyclohexane-1,2-dione

Dioxo-8a-methyl-l, 2,3,4,6,7,8,8a-octahydronaphthalene has been obtained through the reaction of 2-methyl-l,3-cyclohexane-dione with acetonedicarboxylic acid and formaldehyde,3 4-diethyl-amino-2-butanone methiodide,3 pyridine and 4-diethylamino-2-butanone,4 triethylamine and 4-diethylamino-2-butanone,5 and by cyclization of 2-methyl-2-(3-oxobutyl)-l,3-cyclohexanedione using either aluminum fer/-butoxide or piperidine phosphate as catalyst.6 7... 

The conversion of resorcinol to 2-methyl-l,3-cyclohexane-dione can be effected by first isolating the dihydroresorcinol2 and subjecting it to the methylation reaction. However, this procedure is more laborious and the yield is no better. 

A mixture of 63.1 g. (0.5 mole) of 2-methyl-l,3-cyclohexane-dione (Note 1), 52.6 g. (0.75 mole) of methyl vinyl ketone (Note 2), about 0.25 g. (3 pellets) of potassium hydroxide, and 250 ml. of absolute methanol is placed in a 500-ml. round-bottomed flask fitted with a reflux condenser and a drying tube (Note 3). The mixture is heated under reflux for 3 hours, and the dione gradually goes into solution. At the end of this period, methanol and the excess methyl vinyl ketone are removed by distillation under reduced pressure (Notes 4 and 5). The residual liquid is dissolved in 250 ml. of benzene, a Dean-Stark phase-separating head is attached, and 20 ml. of solvent is removed by distillation at atmospheric pressure to remove traces of water and methanol. The solution is cooled well below the boiling point, 3 ml. of... 

Bis-carboxonium ions such as 73 can be directly observed using low-temperature NMR. In the case of 73, 2,4 pentanedione is dissolved in FS0sH-SbF5-S02 solution at — 60°C and the 1H NMR shows three absorptions, including the carboxonium protons.32 In some cases (especially in weaker superacid systems), the diprotonated species form equilibrium mixtures with the monoprotonated species. When either 1,3-cyclohexane-dione or 2-methyl-l,3-cyclopentanedione is reacted in very strong superacids, only the monoprotonated species are observed.32 This is attributed to increased stability of the enol-type cations, 90 and 91, when compared with the acyclic systems. 

The work by Ramachandran and Newman cited above shows that 2-methyl-cyclohexane-1,3-dione (T) reacts smoothly with methyl vinyl ketone by Michael addition and aldolization to give the methyloctalindione III in good yield. In contrast, the condensation of 2-methylcyclohexanone (2) with methyl vinyl ketone (1) under comparable conditions proceeds very poorly. Marshall and Fanta, " after numerous unsuccessful attempts to improve the yield, found that slow addition of methyl vinyl... 

A. 2,2-Vimethylcyolohexcme-l,3-dione. In a 1-L, three-necked, round-bottomed flask equipped with a magnetic stirrer, 200-mL, pressure-equalizing dropping funnel and reflux condenser (the top of which is connected to a calcium chloride drying tube) are placed 50.4 g (0.4 mol) of 2-methyl -cyclohexane-1,3-dione and 500 mL of dry methanol. To this stirred solution is added dropwise 168 mL of commercial Triton B (40% in methanol) (Notes 1 and 2). After the addition Is complete, the resulting solution is stirred at room temperature for 10 min and 60.0 g (0.423 mol) of methyl iodide is added portionwise. This solution is then stirred and heated under reflux for 16-20 hr (Note 3). After the reaction mixture 1s cooled to room temperature, about 400 mL of methanol is removed by rotary evaporation. The residue 1s poured into a mixture of 100 nt (1.2 mol) of coned hydrochloric acid and about 100 g of ice to decompose the O-alkylated product (Note 4), and the mixture 1s stirred for 30 min. The precipitated solid (recovered starting material) 1s... 

Hydroxymethylene-5-methylcyclohexanone in methanol added to aq. Na-acetate, then benzenediazonium chloride soln. prepared from aniline added during 25 min. with stirring 4-methyl cyclohexane-1,2-dione 1-phenylhydrazone. Y 1S%. D. P. 

Some polymerization systems progress without initiators of polymerization. Those systems are not influenced by oxygen. A combination of bis-maleimide (bis[l-(2-ethyl-4,6-dimethylphenyl)pyrrolidine-2,5-dion]) and vinylether (l,4-bis[(ethenyloxy)methyl]cyclohexane) is polymerized under high reaction speed without an initiator. Those molecules are shown in Figure 1.6. No inhibition by oxygen is found in this polymerization system. 

Michael reaction of 2-methyl-cyclohexane-1,3-dione with vinylketone give optically pure Wieland-Miescher ketone (Scheme 2A) ... 

Typical procedure. 3-(BenzoYloxY)-3-[(benzoYloxY)methYl]cYclohexane-1,2-dione 1878 [1398] Trifluoroacetic anhydride (104 pL, 155 mg, 0.74 mmol) was added over 5 min to a solution of dimethyl sulfoxide (70 pL, 77 mg, 0.99 mmol) in dry dichloromethane (1.1 mL) at 70 °C under argon. After stirring for 20 min at —70 °C, 2-(benzoyloxy)-2-[(benzoyloxy)methyl]-6-hydroxycyclohexane (192 mg, 0.5 mmol) was added over 5-10 min, and stirring was continued for a further 30 min. Triethylamine (20 pL, 15 mg, 0.1 mmol) was then added over 10-15 min, the solution was allowed to warm to room temperature, and water was added. The mixture was extracted with diethyl ether, and the combined extracts were washed with 5% aq. hydrochloric acid and water, dried over sodium sulfate, and concentrated under reduced pressure. The residue was chromatographed on silica gel (100-200 mesh, 15 g) eluting with 10% ethyl acetate/hexane to give the product, which was crystallized from methanol yield 125 mg (0.34 mmol, 68%) of 1878. 

Figure 3.6 Michael addition of 2-methyl-cyclohexane-l,3-dione to methyl vinyl ketone catalysed by Mg(OH,F)2 catalysts. Yield (above) and selectivity (below) versus reaction time. (Reprinted with permission from [16] Copyright (2005) Elsevier Ltd.)...

Whilst the solution is still hot, add dilute hydrochloric acid until the stirred solution is just acid to litmus, and then distil off as much ethanol as possible, using the water-bath. Now add more dilute hydrochloric acid to the residual hot solution until it is just acid to methyl-orange. The 5,5-dimethyl-cyclohexan-1,3-dione separates as an oil which solidifies on cooling. Filter the product at the pump, wash it with ice-cold water, and dry it in a desiccator. Yield of the pale cream-coloured crystals, 12 g. m.p. 136-145 (preliminary softening). 

The first series of soluble oligo(/ ara-phenylene)s OPVs 24 were generated by Kern and Wirth [48] and shortly after by Heitz and Ulrich [49]. They introduced alkyl substituents (methyls) in each repeat unit and synthesized oligomers 24 up to the hexamer. Various synthetic methods, like the copper-catalyzed Ullmann coupling, the copper-catalyzed condensation of lithium aryls, and the twofold addition of organomelallic species to cyclohexane-1,4-dione, have been thereby investigated. 

Cyclohexane, methyl, 55, 112 CYCLOHEXANECARBOXYLIC ACID, 1 cyano-2-methyl-, ethyl ester, 55, 57 CYCLOHEXANONE, 2,3-epoxy- [7-Oxa-bityUo[4 1 0]heptan-2-one], 55, 52 2-Cyclohexen-l-one, 55, 52 5-Cyclohexene-l,4-dione, 2,3-dichloro-2,5-di-fm-butyl- [5-Cyclohexene-l,4-dione, 2,3-dichloro-2,5-bis( 1,1-di-methylethyl)-], 55, 32 5-Cyclohexene-l, 4-dione, 2,3,5-tnchloro-... 

Cyclohexane, methyl-, 55, 112 CYCLOHEXANFCARBOXYLIC ACID, 1-cyano-2-methyl-, ethyl ester, 55, 57 2-Cyclohexen-l-one, 55, 52 5-Cyclohexene-1,4-dione, 2,3-dichloro-2,5-... 

Because free or esterified imidazole(4,5)-acetates 745 are currently accessible only via a rather tedious multistep synthesis via (4,5)hydroxymethylimidazole [224— 226], it seemed obvious to react amidines such as isobutyraminidine-HCl 742 with commercially available methyl or ethyl 4-chloroacetoacetates 743a, b to obtain 745 directly in one step. Because of the low reactivity of the 4-chlorine in 743, however, reaction of 743, e.g. with isobutyramidine-HCl 742 in the presence of sodium methylate in methanol, affords exclusively 2-isopropyl-6-chloromethyl-pyri-midin-4-one 744 [227], whereas treatment of 743b with NaOEt in EtOH gives, in the absence of amidines, 2,5-bis(ethoxycarbonyl)cyclohexane-l,4-dione in nearly quantitative yield [228, 229]. 

Methyl-2-chlorophenol, see 4-Methylphenol Methyl-4-chlorophenylcarbamate, see Monuron 4-Methylcycloheptanone, see Methylcyclohexane 2-Methyl-2,5-cyclohexadiene-l,4-dione, see MCPA Methylcyclohexane, see Benzene, Cyclohexane, Heptane... 

Since the advent of multipulse-NMR techniques, more detailed 1H-NMR studies on methylcyclo-hexanes547, phenylcyclohexanes548, neomenthyl halides549 and bicydo[4.4.0]decanes 550 551 have been undertaken. The two diastereomeric 4-fm-butyl-7,ll-diphenylspiro[5.5]undecane-1,9-diones (3) and (4) could be identified unambiguously552, and substituted spirodioxane cyclohexanes such as, 9- m-butyl-2-methyl-1.3-dioxaspiro[5.5]undecane (5), have also been investigated553,554. 

N-Substituted quinoxalines are obtained from N-substituted o-phenylenediamines. Thus methyl 2,3-dibromopropionate condenses with (V,A -bis(/7-toluenesulfonyl)-o-phenylenediamine to give l,4-bis(p-tolu-enesulfonyl)-2-methoxycarbonyl-1,2,3,4-tetrahydroquinoxaline (20).25 AVV -Disubstituted cyclohexane-1,2-diamines with suitable a/7-dihalides yield decahydroquinoxalines.26 Condensation of cyclohexane- 1,2-diones with glycine amide gives 2-oxo-5,6,7,8-tetrahydroquinoxalines.27... 

Another simplified nomenclature adopted here relates to natural spiro-2,3-dihydrobenzofuran derivatives, such as griseofulvin. The fundamental heterocycle, named grisan, being spirobenzofuran-2(3ff)-l -cyclohexane (5), griseofulvin (7-chloro-4,6,2 -trimethoxy-6 -methyl-spirobenzofuran-2(3//)-l -[2]cyclohexene-3,4 -dione) (6) becomes 7-chloro-4,6,2 -trimethoxy-6 -methyl-2 -grisene-3,4 -dione. 

During the reductive isomerization of 7/3-methyl- 14-isoestr-4-ene-3,17-dione 272 in HF SbF5/methylcyclopentane at 0°C, it was found879 that a 1,3-hydride shift occurs followed by kinetically controlled hydride transfer (Scheme 5.91). The mechanism of the reaction was confirmed by employing the deuteriated donor cyclohexane- as well as a specifically deuterium-labeled starting steroid. 

With alkyl methyl ketones (R-CH2,CO,Me) the reaction is complicated by the presence of two alternative sites of oxidation in practice the methyl group appears to be oxidised in preference to the methylene group for reasons which have not been adequately clarified, but in any case the yields are usually poor. Unsubstituted, or symmetrically substituted cyclic ketones possessing of course an a-methylene group, are similarly converted into 1,2-diketones (e.g. the formation of cyclohexane-l,2-dione from cyclohexanone, Expt 5.99, cognate preparation) unsymmetrically substituted cyclic ketones would normally give rise to regioisomers. 

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