Dimethyl carbonate ketones

Comparison of the configuration of the stannane with the prodncts of reaction reveals that primary alkyl halides that are not benzyhc or a to a carbonyl react with inversion at the lithium-bearing carbon atom. In the piperidine series, the best data are for the 3-phenylpropyl compound, which was shown to be >99 1 er. In the pyrrolidine series, the er of the analogous compound indicates 21-22% retention and 78-79% inversion of configuration. Activated alkyl halides such as benzyl bromide and teri-butyl bromoacetate afford racemic adducts. In both the pyrrolidine and piperidine series, most carbonyl electrophiles (i.e. carbon dioxide, dimethyl carbonate, methyl chloroformate, pivaloyl chloride, cyclohexanone, acetone and benzaldehyde) react with virtually complete retention of configuration at the lithium-bearing carbon atom. The only exceptions are benzophenone, which affords racemic adduct, and pivaloyl chloride, which shows some inversion. The inversion observed with pivaloyl chloride may be due to partial racemization of the ketone product during work-up. 

The protocol described also can be used for the acylation of ketone enolates with carbonic acid derivatives (Figure 13.62). Especially good acylating agents are cyanocarbonic acid methyl ester (Mander s reagent, Figure 13.62, top) and dialkyl pyrocarbonates (bottom). Usually it is not possible to use dimethyl carbonate for the acylation of ketone enolates because dimethyl carbonate is a weaker electrophile than cyanocarbonic acid methyl ester or diethyl pyrocarbonates. 

In Stork s synthesis (148), 5 - methyl - 6 - methoxy - 1 - tetralone (CLXXXIV) was converted into the tricyclic intermediate CLXX XVII in several steps involving condensation with dimethyl carbonate, addition of methyl isopropenylketone, and cyclization to the a, -unsaturated ketone CLXXXVI, followed by catalytic hydrogenation, replacement of the hydroxyl group in the resulting dihydro alcohol by a chlorine atom on treatment with phosphorus oxychloride in pyridine solution, and elimination of hydrogen chloride by methanolic sodium methoxide. 

Carbomethoxylation. In one stage of a total synthesis of dZ-caryophyllene, Corey et al.1 treated the cyclic ketone (1), 7,7-dimethylbieyclo[4.2.0]octanone-2, in dioxane with sodium hydride and dimethyl carbonate at 80-85° and obtained the /3-keto ester (2) in high yield. 

Aldehydes and ketones contain a carbonyl group (C=0) in which the carbonyl carbon is not directly attached to any atoms other than hydrogen or carbon. Aldehydes have either one or two hydrogens directly attached to the carbonyl carbon. Ketones contain only carbons directly attached to the carbonyl carbon. Methanal (common name formaldehyde) is the only aldehyde with two hydrogens attached to the carbonyl carbon. The simplest aldehyde with one hydrogen attached to the carbonyl carbon is ethanal (common name acetaldehyde). The simplest ketone is propanone (common names dimethyl ketone, acetone). 

Acetone, acetic acid (glacial), lower alcohols, alcohol/ diethyl ether, amyl acetate, M-butyl acetate, butyl lactate, 7-butyrolactin, cyclopentanone, diethyl acetate, diethyl ketone, N,N-dimethylacetamide, dimethyl carbonate, dimethyl cyanamide, dimethylformamide, dimethyl maleate, dimethylsulfoxide, 2-ethoxyethyl acetate, ethyl acetate, ethyl amyl ketone, ethylene glycol ethers, ethyl lactate, 2-hexanone, methyl acetate, methyl ethyl ketone, methyl propyl ketone, M-methylpyrrolidone-2, 2-octanone, 1-pentanone, M-pentyl acetate, pyridine ... 

Co (CO) 2, and (n -C5H5)(n -Ci4Phtj)Co. 35 As a consequence, alternate methods for the preparation of functionally substituted cyclo-pentadienyl metal compounds became an important goal of our research. Sodium cyclopentadienide containing aldehyde, ketone, and ester substituents can be made by the reactions of C5H5Na with ethyl formate, methyl acetate, methyl chloroformate, and dimethyl carbonate (Scheme l),36-39... 

Among the important oxygenated solvents that are not covered above are furan solvents and organic carbonates. Furan solvents of commercial interest include furfuryl alcohol, tetrahydrofuran, and tetrahydrofurfuryl alcohol. They are characterized by strong solvency for some synthetic polymers. Tetrahydrofuran has an evaporation rate between that of acetone and methyl ethyl ketone. Organic carbonate solvents include ethylene and propylene carbonates, diethyl carbonate and dimethyl carbonate, which are good solvents for many polymers. 

C3H3O3 dimethyl carbonate 7.7 2 methyl propyl ketone 9.93 15... 

Julia substrate 41 was prepared as follows. Cyclopropylketone 42 was converted to the corresponding /3-ketoester using sodium hydride and dimethyl carbonate. The anion derived from the /3-ketoester was alkylated with allylic bromide 43 to provide 44a. Ester hydrolysis, decarboxylation of the intermediate /3-ketoacid, and esterification of the terminal carboxylic acid using diazomethane, gave ketone 44b (CJH-5). 

Solubility of PVDF in some organic solvents. DEC, diethyl carbonate DlOX, dioxane DMA, dimethyl acetamide DMC, dimethyl carbonate DMF, dimethyl formamide DMI, 1,3-dimethyl-2-imidazolidinone DMSO, dimethyl sulfoxide EGDM, ethylene glycol dimethacrylate EP, l-ethyl-2-pyrrolidinone MEK, methyl ethyl ketone MP, l-methyl-2-pyrrolidinone NMP, N-mehtyl-2-pyrrolidone PC, propylene carbonate y-BL, y-butyrolactone . 

The physical properties of finish removers vary considerably due to the diverse uses and requirements of the removers. Finish removers can be grouped by the principal ingredient of the formula, method of appHcation, method of removal, chemical base, viscosity, or hazardous classification. Except for method of apphcation, a paint remover formulation usually has one aspect of each group, by which it can be used for one or more appHcations. A Hst of the most common organic solvents used in finish removers has been compiled (3). Many are mentioned throughout this article others include ethyl lactate [97-64-3] propylene carbonate [108-32-7] furfural alcohol [98-01-1/, dimethyl formamide [68-12-2] tetrahydrofuran [109-99-9] methyl amyl ketone [110-43-0] dipropylene glycol methyl ether [34590-94-8] and Exxate 600, a trade name of Exxon Chemicals. 

Dimethyl ketals and enol ethers are stable to the conditions of oxime formation (hydroxylamine acetate or hydroxylamine hydrochloride-pyridine). Thioketals and hemithioketals are cleaved to the parent ketones by cadmium carbonate and mercuric chloride. Desulfurization of thioketals with Raney nickel leads to the corresponding methylene compounds, while thioenol ethers give the corresponding olefin. In contrast, desulfurization of hemithioketals regenerates the parent ketone. ... 

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