Phosphorus oxybromide → HCID 178444245, compound

Participants

Reaction Conditions

Reaction Steps

24.8 g of 6-(trans-4-pentylcyclohexyl)-3(2H)-pyridazinone (prepared according to Example 2) and 150 ml of toluene were suspended in a sulphonation flask under nitrogen. Subsequently, there was added dropwise within 7 minutes a solution of 11.5 g of phosphorus oxybromide, the temperature rising from 17° C. to 30° C. and a viscous light brown mass resulting. The mixture was treated with 30 ml of toluene and then heated slowly to 68° C., whereby it became dark green in colour. After 2 hours, a solution of 5.7 g of phosphorus oxybromide was added dropwise at 68° C. within 10 minutes. The mixture was heated to reflux temperature and once more treated with a solution of 7.4 g of phosphorus oxybromide. After 6 hours, the mixture was poured into 400 ml of ice/water and extracted six times with 250 ml of methylene chloride each time. The organic phases were washed with 400 ml of 5% sodium hydrogen carbonate solution, subsequently combined, dried with sodium sulphate and concentrated at 40° C. on a rotary evaporator. Column chromatography on silica gel with ethyl acetate/hexane (1:1) as the eluant gave 24.81 g of crude product. Crystallization from 75 ml of ethyl acetate/hexane (2:1) and working-up of the mother liquor finally yielded a total of 21.7 g of 3-bromo-6-(trans-4-pentylcyclohexyl)pyridazine as white crystals of melting point 101°-103° C.

Provenance & Evidence