Cyclohexanone reaction with dimethylformamide

Cyclohexanone, 46, 18, 27, 36, 82 reaction with dimethylformamide and phosphorus oxychloride, 46, 18... 

Phosphorus oxychloride, reaction with dimethylformamide and cyclohexanone, 46,18... 

Dimethylformamide, reaction with dimethyl sulfate, 47, 52 reaction with phosphorus oxychloride and cyclohexanone, 16,18 Dimethylformamide-dimethyl sulfate complex, preparation of, 47,... 

All of the unsymmetrical isomers undergo characteristic color reactions in the presence of base with ketones such as acetone, butanone, or cyclohexanone (Ref 1), and with Na nitrite—N,N-dimethylformamide (Ref 6). By using an appropriate combination of reaction conditions and wavelength for measuring absorptivity, it may be possible to use the second system for automated analysis of the unsymmetrical isomers present in crude 2,4,6-TNT. The 2,4,5-isomer undergoes a rapid color reaction with piperidine of sufficient sensitivity to be of possible use for on-line monitoring in TNT production (Ref 11). Other color reactions are discussed in Vol 3, C405-L ff The reactions of nucleophiles with TNT isomers is the subject of a restricted report (Ref 9)... 

Enaminones 143, derived from the reaction of substituted cyclohexanones with dimethylformamide dimethyl acetal, undergo [3 + 2] cycloaddition with glycinate salts followed by acetic treatment to give the A -acetyl pyrroles 144, = OAc. Deacetylation affords the pyrroles 144, = H,... 

The complete molecular framework is then constructed via a one pot Bischler type alkylation/cyclization/dehydration reaction (3) with 2-bromocyclohexanone. To conduct this chemistry on scale, we required large quantities of 2-bromocyclohexanone. Due no doubt to its limited thermal stability, it is not commercially available. It can be prepared by a simple bromination of cyclohexanone with Bri in methanol, but this results in significant overreaction and the thermally labile product must be purified by vacuum distillation. We required a method that would avoid the distillation of this hazardous material and developed a two step protocol via the TMS enol ether. It is both high yielding and avoids the safety issue. Thus treatment of cyclohexanone in hot dimethylformamide with triethylamine and trimethylsilyl chloride resulted in smooth conversion to the TMS enol ether. After an aqueous... 

It should be noted that several procedures are available for the preparation of l-(trimethylsilyloxy)cyclohexene. In an original report252 it was prepared by heating a dimethylformamide solution of cyclohexanone under reflux with chlorotrimethylsilane in the presence of triethylamine. This procedure is generally satisfactory for aldehydes and symmetrical ketones, or ketones which can enolise in one direction only. The method described in Expt 5.214 employs lithium sulphide as an additive to increase the silylating power of the chlorotrimethylsilane, so that the reaction proceeds at room temperature acetonitrile is used as the solvent.253... 

Capello et al.16 applied LCA to 26 organic solvents (acetic acid, acetone, acetonitrile, butanol, butyl acetate, cyclohexane, cyclohexanone, diethyl ether, dioxane, dimethylformamide, ethanol, ethyl acetate, ethyl benzene, formaldehyde, formic acid, heptane, hexane, methyl ethyl ketone, methanol, methyl acetate, pentane, n- and isopropanol, tetrahydrofuran, toluene, and xylene). They applied the EHS Excel Tool36 to identify potential hazards resulting from the application of these substances. It was used to assess these compounds with respect to nine effect categories release potential, fire/explosion, reaction/decomposition, acute toxicity, irritation, chronic toxicity, persistency, air hazard, and water hazard. For each effect category, an index between zero and one was calculated, resulting in an overall score between zero and nine for each chemical. Figure 18.12 shows the life cycle model used by Capello et al.16... 

To a 100-mL, two-necked flask, is added a mixture of cyclohexanone (5.9 g, 60 mmol), o-iodoaniline (4.4 g, 20 mmol), and 1,4-diazabicyclo[2.2.2]octane (DABCO) (6.7 g, 60 mmol) in N,N-dimethylformamide (DMF) (60 mL). The mixture is degassed three times via nitrogen/vacuum, followed by the addition of palladium acetate (Pd(OAc)2) (2.24 mg, 0.1 mmol) (Note 1). The mixture is degassed twice and heated at 105°C for 3 hr or until completion of the reaction (Note 2). The reaction mixture is cooled to room temperature and partitioned between isopropyl acetate (150 mL) and water (50 mL). The organic layer is separated, washed with brine (50 mL), and concentrated under vacuum to dryness. The residue is chromatographed on 50 g of silica gel using 700 mL of ethyl acetate-heptane (1 6) as the eluent to give 2.22 g of 1,2,3,4-tetrahydrocarbazole (65%) as a pale brown solid (Note 3). 

At the time of the last review1 it was noted that the condensation of ketones with the Reissert anion was a relatively unsatisfactory reaction. It has now been shown that acetone," acetophenone," cyclohexanone," and several N-substituted 4-piperidones109 react with the isoquinoline Reissert compound in the presence of 50% aqueous sodium hydroxide-acetonitrile containingTEBA chloride. Isatin,48 106a N-benzyl-3-piperidone,109 and a variety of N-substituted 4-piperidones109110 also react with isoquinoline or 6,7-dimethoxyisoquinoline Reissert compounds using sodium hydride in dimethylformamide. Thus, isatin and 2 under these conditions gives 52.48... 

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