O[C:2]1[N:7]2[N:8]=[C:9]([CH3:11])[CH:10]=[C:6]2[N:5]=[C:4]([CH3:12])[C:3]=1[CH2:13][CH2:14][CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH3:20].O=P(Cl)(Cl)[Cl:23]>>[Cl:23][C:2]1[N:7]2[N:8]=[C:9]([CH3:11])[CH:10]=[C:6]2[N:5]=[C:4]([CH3:12])[C:3]=1[CH2:13][CH2:14][CH2:15][CH2:16][CH2:17][CH2:18][CH2:19][CH3:20]190 g of the condensate obtained from (a), in 550 ml of phosphorus oxytrichloride, are refluxed for 1.5 hours, after which the excess phosphorus oxytrichloride is evaporated under reduced pressure and the residue is stirred with 500 ml of CH2Cl2 and 500 ml of ice water. The organic phase is separated off, washed with three times 100 ml of ice water, dried over sodium sulfate and filtered, the solvent is evaporated under reduced pressure, and 179 g of 7-chloro-2,5-dimethyl-6-n-octylpyrazolo-[1,5-a]pyrimidine are isolated as a viscous mass.
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