Dimethylformamide s. a. under

Dimethylformamide (s. a. under Iron(III) chloride, Thionyl chloride)... 

The C-S bond in purine derivatives undergoes cleavage under mild conditions by nucleophilic agents such as benzylmercaptan or glutathione in dimethylformamide with a phosphate buffer of pH 6.5 (277). The salt (110) of dithiazolylsulfide heated at 190 C yields the A-4-thiazo-line-2-thione (112) and 2-chlorothiazole (111) (Scheme 56) (278-280). 

Kofler) and dihydrochloride of l-p,p -difluorobenzhydryl piperazine, melting point 178°-180°C (capillary) in anhydrous dimethylformamide are heated under reflux. On completion of this operation the solvent is removed under vacuum and the residue taken up in a mixture of chloroform and of water (1 1). The organic phase is separated, and repeatedly extracted with aqueous N-methanesulphonic acid and the aqueous acidic layers separated. The aforementioned acidic solutions are then combined and rendered alkaline (pH 10) with dilute aqueous sodium hydroxide, the base extracted with ether, the extract dried over anhydrous potassium carbonate, and filtered. The etheral filtrate, upon evaporation yields the 2,4-bis(allylamino)-6-(4-(bis(p-fluorophenyl)methyl)-l-piperazinyl)-s-triazine, melting point 175°-180°C. 

The experimental conditions for conducting the above reaction in the presence of dimethylformamide as a solvent are as follows. In a 250 ml. three-necked ilask, equipped with a reflux condenser and a tantalum wire Hershberg-type stirrer, place 20 g. of o-chloronitrobenzene and 100 ml. of dimethylformamide (dried over anhydrous calcium sulphate). Heat the solution to reflux and add 20 g. of activated copper bronze in one portion. Heat under reflux for 4 hours, add another 20 g. portion of copper powder, and continue refluxing for a second 4-hour period. Allow to cool, pour the reaction mixture into 2 litres of water, and filter with suction. Extract the solids with three 200 ml. portions of boiling ethanol alternatively, use 300 ml. of ethanol in a Soxhlet apparatus. Isolate the 2 2- dinitrodiphenyl from the alcoholic extracts a.s describe above the yield of product, m.p. 124-125°, is 11-5 g. 

A soln. of guanylurea in abs. methanol treated with dimethylformamide dimethyl acetal, and allowed to stand overnight at room temp, under anhydrous conditions -> 5-azacytosine. Y 91%. Also with ethyl orthoformate in dimethylformamide and f. e. with orthocarboxylic acid esters s. A. Piskala, Coll. 32, 3966 (1967). 

A mixture of 3-benzoyldihydro-2(3H)-furanone and NaBr in dimethyl sulfoxide heated 6 hrs. at 160° under Ng cyclopropyl phenyl ketone. Y 91.5%. F. e., also with NaCl and in dimethylformamide, s. S. Takei and Y. Kawano, Tetrah. Let. 1975, 4389. 

PClj added dropwise with stirring under Ng to dimethylformamide so that the mixture becomes warm, stirring discontinued, allowed to stand 40 min., 3-penta-nol added, and stirred 20 min. product. Y 84%. F. e. s. A. G. Anderson, Jr., et al., Synthesis 1976, 398. 

Acetoxy-2,6-di-t rf-butyl-4-methyl-2,5-cyclohexadienone in dimethylformamide added under Ng to a stirred soln. of K-rer/-butoxide in dimethylformamide, and allowed to stand 1 hr. at room temp. 6-methyl-2,4-di-t r/-butyl-3-hydroxy-phenylacetic acid. Y 83%. F. e. s. A. Nishinaga et al.. Synthesis 1976, 553. 

A. (S)-Ethyl 2-(t-Butyldimethylsilyloxy)propanoate (1). A 2-L, two-necked, round-bottomed flask equipped with a mechanical stirrer and inert gas inlet (Note 1) is charged with (S)-ethyl lactate (118 g, 1.0 mol), 500 mL of dimethylformamide (DMF), and imidazole (102 g, 1.5 mol) (Note 2). The solution is cooled in a ice bath and te/ t-butyldimethy 1 si 1 y 1 chloride (TBDMSC1) (150 g, 1.0 mol) is added in three 50-g portions, at intervals of 30 min between each addition. After the addition of the third portion, a white precipitate forms. The ice bath allowed to melt gradually overnight. After 18 hr, the reaction mixture is diluted with 300 mL of water and 500 mL of hexanes. The aqueous phase is separated and extracted with 300 mL of hexanes, and the combined hexane extracts are washed with three 50-mL portions of saturated brine, dried over MgS04, filtered, and concentrated by rotary evaporation to afford 240 g (103%) of the TBDMS ether as a colorless liquid. The product is distilled under vacuum (bp 70-78°C, 0.5 mm bath temperature 95-105°C) (Note 3) to afford 222 g (96%) of ester 1 as a colorless liquid (Notes 4, 5). 

A. cis- and trans-4-Aminocyclohexanecarboxylic acid. A mixture of 27.4 g. (0.20 mole) of />-aminobenzoic acid (Note 1), 200 ml. of water, and 2 g. of 10% rhodium-0.1% palladium on carbon ciitalyst (Note 2) is placed in a pressure bottle and hydrogenated at 50 p.s.i. When 0.6 mole of hydrogen has been absorbed (Note vl), the mixture is filtered and concentrated under reduced pressure until crystals start to form (Note 4). The mixture is diluted with 200 ml. of dimethylformamide and cooled to 5°, filtered, washed with dimethylformamide, then methanol, and amino-cyclohexanecarboxylic acid, m.p. 292-296° (Note 5). 

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