Phosphoric Acid → HCID 70636650, compound

Participants

Reaction Conditions

Reaction Steps

Water (47 cc.) and pyridine (16.1 cc.) are added to the sodium salt of 3-acetoxymethyl-2-carboxy-7-[(5,6-dihydro-1,4-dithiin-2-yl )acetamido]-8-oxo-5-thia-1-aza- bicyclo[4,2,0]oct-2-ene (45.2 g.) and potassium thiocyanate (194 g.). After stirring, a homogeneous syrupy mixture is obtained, the pH of which is adjusted to 6.5 by addition of concentrated phosphoric acid. The mixture is heated at 60° C. for 5 hours. After cooling, the reaction mixture is diluted with distilled water (1 liter) and is washed three times with chloroform (total 800 cc.). The last traces of chloroform in the aqueous phase are removed by distillation under reduced pressure (20 mm.Hg) and the resulting solution is then treated with decolourizing charcoal, filtered through "Supercel" and cooled by means of an ice-water bath. The solution is then acidified to pH 2 by addition of 4 N hydrochloric acid whilst keeping the temperature below 5° C.; a product precipitates. The mixture is stirred for one hour whilst continuing to cool it with a mixture of ice and water, and is then washed twice by decantation with ice-water (1 liter). The precipitate is filtered off and is washed three times with ice-water (total 2 liters). The solid obtained is suspended in water (120 cc.) and a 25% solution of "Amberlite LA 2" in methyl isobutyl ketone (120 cc.) is added. The mixture is stirred until the solid has dissolved completely, and then the organic phase is decanted and discarded. The aqueous phase is extracted twice with a 25% solution of "Amberlite LA 2" in methyl isobutyl ketone (total 240 cc.), then with ethyl acetate (300 cc.) and finally three times with diethyl ether (total 300 cc.). The water is evaporated under reduced pressure (20 mm.Hg) at 40° C. An oil is obtained which is triturated in acetone (800 cc.). The resulting solid is filtered off, washed three times with acetone (total 300 cc.) and then dried under reduced pressure (0.5 mm.Hg). 2-Carboxylato-7-[(5,6-dihydro-1,4-dithiin-2-yl )acetamido]-8-oxo-3- (1-pyridinio-methyl)-5-thia-1-aza-bicyclo[4,2,0]- oct-2-ene (8.3 g.) is thus obtained.

Provenance & Evidence