Methyl iodide → HCID 54535882, compound

Participants

Reaction Conditions

Reaction Steps

To a 1.6M solution (440 cc) of n-butyllithium in hexane, maintained under an atmosphere of argon and cooled to -71° C., a mixture (440 cc) of anhydrous hexamethylphosphorotriamide and anhydrous tetrahydrofuran (47:53 by volume) is added dropwise in the course of 20 minutes. A solution of 2-(6-methyl-2-pyridyl)-1,3-dithiane (97 g) in a mixture (300 cc) of anhydrous hexamethylphosphorotriamide and anhydrous tetrahydrofuran (47:53 by volume) is then added in the course of 30 minutes at a temperature in the region of -70° C. After 1 hour 40 minutes' stirring, carbon disulphide (53 g) dissolved in anhydrous tetrahydrofuran (220 cc) is added in the course of 40 minutes. After 45 minutes' stirring at -70° C., methyl iodide (97 g) dissolved in anhydrous tetrahydrofuran (220 cc) is added in the course of 30 minutes and at the same temperature. The reaction mixture is then stirred for 30 minutes at a temperature in the region of -65° C. and then for 50 minutes while the temperature is allowed to rise gradually to 10° C.; it is then poured into a mixture of distilled water (600 cc) and ethyl acetate (500 cc). After decantation, the aqueous phase is extracted twice with ethyl acetate (600 cc in total). The organic extracts are combined, washed twice with saturated aqueous sodium chloride solution (600 cc in total), anhydrous magnesium sulphate and decolorising charcoal are added, and the mixture is then kept for 15 hours at a temperature in the region of 5° C., filtered and then concentrated under reduced pressure (25 mm Hg; 3.25 kPa) at 50° C. To the product obtained (192.2 g) there is added some product (231.7 g) prepared under the same conditions in a previous operation, and the combined product is chromatographed on neutral silica gel (1.5 kg; 0.063-0.200 mm) contained in a column 8 cm in diameter. The product is eluted with methylene chloride, collecting one fraction (3.5 liters) followed by 7 fractions (600 cc). Fractions 5 to 8 are combined and concentrated to dryness under reduced pressure (25 mm Hg; 3.25 kPa) at 50° C. The product obtained (276.5 g) is dissolved in boiling ethyl acetate (200 cc). The solution obtained is cooled and kept for 1 hour at a temperature in the region of 5° C. The crystals which appear are separated by filtration, washed twice with ethyl acetate (60 cc in total) and then 3 times with isopropyl ether (135 cc in total), and dried under reduced pressure (0.2 mm Hg; 0.03 kPa) at 20° C. Methyl 2-(6-methyl-2-pyridyl)-1,3-dithiane-2-carbodithioate (153.9 g), m.p. 92° C., is thereby obtained.

Provenance & Evidence