Dimethylformamide dimethyl sulfate

Cydopentadienylsodium, reaction with dimethylformamide-dimethyl sulfate complex, 47, S3 1,3-Cyclopentanedione, 2-methyl-, 47, 83... 

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

ACETALIZATION N,N-Dimethylformamide-Dimethyl sulfate. Fyiidinium tosylate. 

An equimolar amount of dimethylformamide-dimethyl sulfate added at -10° during 20 min. with vigorous stirring to a suspension of Na-ethanethiolate in anhydrous ether, and vigorous stirring of the 3-phase mixture continued 0.5 hr. until it becomes 2-phase (dimethylamino)(ethylthio)(methoxy)methane. Y 30%. D. Olsdiwang, Bl. 1971, 3354. 

A. N,N-Dimeihyljormamide-dimelhyl sulfate complex. In a 500-ml. four-necked flask equipped with mechanical stirrer, reflux condenser with calcium chloride drying tube, dropping funnel, and thermometer is placed 73 g. (1.0 mole) of dimethyl-formamide, and 126 g. (1.0 mole) of dimethyl sulfate is added dropwise with stirring at 50-60° (Note 1). After the addition is complete, the mixture is heated for another 2 hours at 70-80°. The dimethylformamide complex forms as a viscous, colorless or pale yellow ether-insoluble oil. 

The value of methylation studies in structural determination of carbohydrates is well known. Methylation of sucrose has generally been achieved by the use of dimethyl sulfate-sodium hydroxide,34,35 methyl iodide-silver oxide-acetone,20 sodium hydride-methyl io-dide-N,N-dimethylformamide,35 or diazomethane-boron trifluoride etherate.36,37 The last method (already applied to monosaccharides38,39) has been found particularly useful for sucrose, because it proceeds without concomitant migration of acyl groups. The reaction of 2,3,6,T,3, 4, 6 -hepta-0-acetylsucrose (21) and 2,3,4,6,1, 3, 4 -hepta-O-acetylsucrose (22) with diazomethane in dichloromethane in the presence of a catalytic proportion of boron trifluoride etherate for 0.5 h at —5° gave the corresponding 4-methyl (23) and 6 -methyl (24)... 

Octa-O-methylsucrose has been prepared by treating sucrose with either dimethyl sulfate-sodium hydroxide, or sodium hydride and methyl iodide in A/,A/-dimethylformamide.35... 

The hydroxyl group of ethyl 2-hydroxy-4-oxo-4//-pyrimido[2,l-a]-isoquinoline-3-carboxylate (20) was methylated with methyl iodide in dry boiling acetone for 5 h in the presence of potassium carbonate, with dimethyl sulfate in methylene chloride in methanol in the presence of Triton B at 20°C for 18 h, with methyl fluorosulfonate in 2.5 M sodium hydroxide at 20°C for 5 h, and with diazomethane in a mixture of diethyl ether and methylene chloride at 20°C for 3 h to give the 2-methoxy derivative (89AJC2161). The hydroxy group of 3-hydroxymethyl-4//-pyrimido[2,l-b]-isoquinolin-4-one was alkylated and acylated with 2-(diethylamino)ethyl chloride in dimethylformamide in the presence of sodium hydroxide, and with acetic anhydride in boiling chloroform in the presence of triethylamine and a few drops of 4-dimethylaminopyridine, respectively (86EUP 166439). 

Dimethylaminonitroethylene is prepared from the anion of nitromethane and the salt prepaffed from dimethylformamide and dimethyl sulfate. The condensation step is general for other types of active methylene compounds, indicating further potential for pyrrole synthesis. A related process involves the condensation of ketones with the moao-N,N-dimethylhydrazone of glyoxal base-catalyzed condensation affords the hydrazones of a conjugated 1,4-dicarbonyl system, and sodium thiosulfate reduction then affords 2,3-disubstituted pyrroles (equation 85) (77CB491). 

Dimethyl sulfate (126.1 g, 1.0 mole) was heated to 65°C. The temperature was maintained at 60-70°C while dimethylformamide (73.1 g, 1.0 mole) was added over a period of about 30 minutes. After the addition was complete, the reaction was heated at 70°C for 7 hours, then cooled to below 30°C. n-Octylamine (129.2 g, 1.0 mole) was added over a 20 minute period with external cooling to maintain the temperature at 40°C. The reaction was stirred an additional 3 hours at 40°C after addition was complete. The reaction was cooled to about 10°C and treated with toluene (200 ml), water (200 ml) and finally 27% sodium hydroxide solution (180 g, 2 moles). The organic phase was separated, dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure to yield 190 g of a light yellow liquid which was fractionally distilled twice to yield 113 g (61%) of the title compound as a water white liquid b.p. 115.-117°C at 15 mm Hg. 

Dimethylphenylthiocrea, 46, 70 Dimethylphosphine, 46, 103 Dimethylphosphinic acid, 45, 103 Dimethylphosphinyl chloride, 45, 103 Dimethyl sulfate, reaction with dimethylformamide, 47, 52... 

Dimethylformamide and dimethyl sulfate must be purified by distillation in the absence of moisture. 

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