Ammonia → 4-Carbamoyl-5-(pyrazin-2-yl)-1,2-dithiole-3-thione

Participants

Reaction Conditions

Reaction Steps

A suspension of 4-carboxy-5-(pyrazin-2-yl)-1,2-dithiole-3-thione (12.8 g) [prepared as described in Example 32] and 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (13.25 g) in methylene chloride (40 cc) is stirred for 5 hours at a temperature of about 20° C. A solution (15 c) of 4N ammonia in methanol is added over a period of 10 minutes to the solution obtained, and the reaction mixture is stirred for a further 5 minutes at a temperature of about 20° C. The insoluble product is filtered off and washed successively with methylene chloride (50 cc), saturated aqueous sodium bicarbonate solution (25 cc), water (4 × 100 cc) and then ethyl acetate (15 cc). The residue obtained is dissolved at a temperature of about 100° C. in dimethylformamide (100 cc) and the solution, which is filtered hot, is then poured into distilled water (200 cc). After cooling to a temperature of about 20° C., the insoluble product is filtered off and washed with ethyl acetate (2 × 10 cc) to give 4-carbamoyl-5-(pyrazin-2-yl)-1,2-dithiole-3-thione (6.58 g) melting at 267° C.

Provenance & Evidence