Phosphorus oxychloride → 6-Chloro-3-methoxy-5,10-diaza-benzo[c]fluoren-7-one

Participants

Reaction Conditions

Reaction Steps

The mixture of 3-methoxy-5H-5,9-diaza-benzo[c]fluorene-6,7-dione and 3-methoxy-5H-5,10-diaza-benzo[c]fluorene-6,7-dione (8.77 g) obtained above was suspended in phosphorus oxychloride (359 g) and stirred at 60° C. for three days. Excess phosphorus oxychloride was evaporated under reduced pressure. The residue was treated with ice water and saturated sodium hydrogen carbonate to adjust the pH about 7. Black precipitate was collected with suction and washed water. The precipitate was purified by silica gel column chromatography developed by dichloromethane-methanol-trifluoroacetic acid (200:2:1) and by dichloromethane-methanol-trifluoroacetic acid (200:4:1). This chromatography gave two yellow bands. The first band was collected and evaporated. The residue was treated with methanol to give less polar isomer (1.72 g), 6-chloro-3-methoxy-5,10-diaza-benzo[c]fluoren-7-one (Reference Example 1c-1) as a yellow powder. The second band was collected and evaporated. The residue was treated with methanol to give more polar isomer (1.86 g), 6-chloro-3-methoxy-5,9-diaza-benzo[c]fluoren-7-one (Reference Example 1c-2) as a yellow powder.

Provenance & Evidence