Dimethyl sulfate, reaction with dimethylformamide

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

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

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)... 

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... 

The flask containing the solution of the (+)-(3aS,7aS)-2,3,3a,4,7,7a-hexahydro-3a-hydroxy-7a-methyl-lH-indene-1,5(6H)-dione in N,N-dimethyl -formamide is placed 1n an oil bath and heated to 95°C. When the temperature reaches 70-75°C, an 18.8-mL aliquot of the coned sulfuric acid in N,N-dimethylformamide solution is added in one portion. The reaction mixture is heated to 95°C for 3.0 hr. After 1.0 hr, an additional 7.5-mL aliquot of the coned sulfuric acid in N,N-dimethy1formamide solution is added in one portion. The reaction is monitored for completeness by GLC (Note 15) and cooled. The solvent is removed on a rotary evaporator at 45°C (0.3-0.5 ran) to give a brown oil. The material is taken up in 375 mL of dlchloromethane. The solution is washed with two 190-mL portions of 2.0 N sulfuric acid solution which have been saturated with sodium chloride, two 190-mL portions of saturated sodium bicarbonate solution which have been saturated with sodium chloride and 190 mL of saturated brine. Each aqueous wash is extracted, in turn, with the same two 190-mL portions of dichloromethane. The combined dichloromethane solutions are dried over sodium sulfate, filtered, and the solvent is removed on a rotary evaporator at 40°C (70 mm) to give 38.8-39.6 g of oily, brown semisolid. This material is taken up in 78 mL of ethyl acetate and the solution is applied to a dry column of 78 g of silica gel (Note 16). The column is eluted with 600 mL of ethyl acetate and the total eluate is... 

Two German patents by Muller describe preparative methods which avoid the use of hydrazoic acid by heating sodium azide with ammonium chloride or sulfate in aqueous solution. A recent Japanese patent describes a reaction between sodium azide and ammonium carbamate in liquid ammonia to give ammonium azide. Evans, Yoffe, and Gray have suggested the reaction of sodium azide with ammonium chloride in iV,iV-dimethylformamide. A modification of the last method has been made it involves the reaction of sodium azide and ammonium sulfate in dimethyl-formamide to give anhydrous ammonium azide of high purity. 

A mixture of dimethyl a,8-dibromoadipate (69 g, 0.21 mol) and potassium phthalimide in dimethylformamide (260 mL) was heated at 90 °C for 40 min. The reaction mixture was then cooled, diluted with CC14 (300 mL) and H2O (1200 mL) and extracted with CCI4 (2 x 100 mL). The combined organic extracts were washed successively with aqueous NaOH (200 mL, 0.1 M) and H20 (200 mL), then dried over sodium sulfate. After concentration under reduced pressure, the addition of ether (300 mL) induced a rapid crystallisation. Recrystallisation with EtOAc gave the phthalimide derivative 75 (87 g, 90%). 

Chloro-5-(1 -Cyclohexenyl)-1-Methyl-2-Oxo-2,3-Dihydro 1 H-Benzo(f)Diazepine-1,4 9.7 grams of sodium methylate are added to a solution of 16.5 grams of 7-chloro-5-(1 -cyclo-hexenyl)-2-oxo-2,3-dihydro 1 H-benzo(f)diazepine-1,4 dissolved in 120 ml of dry dimethyl-formamide and the mixture stirred for one-half hour. The reaction mixture Is cooled in a water bath and a solution of 33.8 grams of methyl iodide dissolved in 35 ml of anhydrous dimethylformamide is then slowly added with stirring. The solution becomes dark brown in color and a precipitate forms. It is stirred for 2 hours, then diluted with a large volume of water and extracted with ethyl acetate. The ethyl acetate solution is washed with water, dried over anhydrous sodium sulfate and the solvent evaporated under reduced pressure. The residue is crystallized from a small volume of ethyl acetate. Brownish yellow crystals are obtained (9 grams yield, 52%), MP < = 144°C. 

A 10-mL Schlenk tube is charged with the iron catalyst (10.6 mg, 0.025 mmol) and triphenylphosphane (7.3 mg, 0.03 mmol) that are then dissolved under argon in dry dimethylformamide (1 mL) and heated to 80 °C for 30 min. The mixture is cooled to room temperature, and the allyl carbonate (186 mg, 1 mmol) and dimethyl malonate (232 mg, 2 mmol) are added. The reaction mixture is heated in the sealed Schlenk tube for 24 h at 80 °C. Then it is cooled to room temperature and dichloromethane (20 mL) is added. The organic layer is washed with water (2 x 10 mL) and dried over a mixture of sodium sulfate and charcoal (1 1 5 g). After filtration and evaporation of the solvent a pale yellow liquid is obtained that is purified by flash column chromatography (isohexane/diethyl ether, 5 1) to afford the product as a colorless liquid 162 mg (81%) R/ 0.43 (hexanes/diethyl ether, 5 1). ... 

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