Phosphoric Acid → (6R,7R)-3-Hydroxymethyl-7-[2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylic acid

Participants

Reaction Steps

Sodium hydroxide (16.0 g) an orthophosphoric acid (13.5 ml) were dissolved in distilled water (750 ml). (6R,7R)-3-Acetoxymethyl-7-[2-methoxyimino-2-(fur-2-yl) acetamido]ceph-3-em-4-carboxylic acid (syn isomer ) (50g.), was added, and this dissolved to give a solution with a pH of 6.4. The pH was adjusted to 6.3 by addition of 20% orthophosphoric acid, and a suspension of Rhodosporidium toruloides CBS 14 cells (150 g.) was added. The mixture was stirred and aerated for 8 hours at 25° during which time M sodium hydroxide solution (105 ml.) had to be added to keep the mixture in the pH range 5.8 to 6.3. Thin layer chromatography showed that the conversion was complete. The mixture was stirred and aerated for a further 16 hours then the yeast removed by centrifugation. The yeast was washed by suspending in water (200 ml.) and recentrifuging. The main function was stirred with charcoal (2 g.) for 30 minutes then filtered through a Hyflo Supercel bed. The bed was washed with the yeast washings. Sodium chloride (250 g.) and 4-methylpentan-2-one (500 ml.) were added to the filtrate, and the pH was adjusted to 2.0 by addition of 20% orthophosphoric acid over 20 minutes. The mixture was cooled in an ice-bath during the acidification. The stirrer was stopped and the layers were allowed to settle. The clear aqueous layer was rejected and the precipitated solid was filtered off and washed with 4-methylpentan-2-one (50 ml) and water (3 × 40 ml.). The product was dried at 40° in vacuo for 24 hours to give the title compound as an off-white solid (38.39 g.) purity by h.p.l.c. 99.1%, total impurities by t.l.c. 2.5%.

Provenance & Evidence