Methyl iodide → HCID 13043962, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of anhydrous hexamethylphosphorotriamide and anhydrous tetrahydrofuran (47/53 by volume; 153 cc) is added dropwise and in the course of 15 minutes to a 1.6 M solution of n-butyllithium in hexane (212 cc), kept under a nitrogen atmosphere and cooled to a temperature of about -60° C. A solution of 2-(pyrid-2-yl)-1,3-oxathiane (34.4 g) in a mixture of anhydrous hexamethylphosphorotriamide and anhydrous tetrahydrofuran (47/53 by volume; 153 cc) is then added in the course of 25 minutes at the same temperature. After stirring for 15 minutes, a solution of carbon disulphide (23.3 g) in a mixture of anhydrous hexamethylphosphorotriamide and anhydrous tetrahydrofuran (47/53 by volume; 153 cc) is added in the course of 15 minutes. After stirring for 5 minutes at -70° C., a solution of methyl iodide (43.4 g) in anhydrous hexamethylphosphorotriamide and anhydrous tetrahydrofuran (47/53 by volume; 153 cc) is added in the course of 10 minutes. The reaction mixture is stirred for 45 minutes at -70° C. and then for 1 hour, whilst allowing the temperature to rise gradually to about 20° C. The reaction mixture is run into a mixture of distilled water (1200 cc) and ethyl acetate (800 cc). After decantation, the aqueous phase is extracted twice with ethyl acetate (1200 cc in total); the organic phases are combined, washed three times with distilled water (1500 cc in total), dried over anhydrous sodium sulphate and filtered and the filtrate is concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 45° C. The product obtained (69.3 g) is chromatographed on neutral silica gel (700 g) contained in a column of diameter 5.4 cm. Elution is carried out successively with cyclohexane (2300 cc), a cyclohexane/ethyl acetate mixture (98/2 by volume; 4000 cc), a cyclohexane/ethyl acetate mixture (95/5 by volume; 7000 cc) and a cyclohexane/ethyl acetate mixture (90/10 by volume; 3000 cc), a first 2300 cc fraction and then fourteen 1000 cc fractions being collected. Fractions 11 to 15 are combined and concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at 45° C. Crude methyl 2-(pyrid-2-yl)-1,3-oxathiane-2-carbodithioate (17.5 g), melting at 116° C., is thus obtained.

Provenance & Evidence