O[C:2]1[N:7]2[N:8]=[CH:9][C:10]([C:11]3[CH:16]=[CH:15][C:14]([CH3:17])=[CH:13][C:12]=3[Cl:18])=[C:6]2[N:5]=[C:4]([CH3:19])[CH:3]=1.P(Cl)(Cl)([Cl:22])=O.C(N(CC)C1C=CC=CC=1)C.C1(C)C=CC=CC=1>CCCCCC.CCOC(C)=O>[Cl:22][C:2]1[N:7]2[N:8]=[CH:9][C:10]([C:11]3[CH:16]=[CH:15][C:14]([CH3:17])=[CH:13][C:12]=3[Cl:18])=[C:6]2[N:5]=[C:4]([CH3:19])[CH:3]=1
A mixture of 7-hydroxy-5-methyl-3-(2-chloro-4-methylphenyl)-pyrazolo[1,5-a]pyrimidine (1.0 g, 3.5 mmol), phosphorus oxychloride (2.7 g, 1.64 mL, 17.4 mmol), N,N-diethylaniline (0.63 g, 0.7 mL, 4.2 mmol) and toluene (20 mL) was stirred at reflux temperature for 3 hours, then it was cooled to ambient temperature. The volatiles were removed in vacuo. Flash chromatography (EtOAc:hexane::1:2) on the residue gave 7-chloro-5-methyl-3-(2-chloro-4-methylphenyl)pyrazolo[1,5-a]pyrimidine (900 mg, 84% yield) as a yellow oil: NMR (CDCl3, 300 Hz): 7.35 (s, 1H), 7.28–7.26 (m, 1H), 71.6 (d, 1H, J=7), 6.80 (s, 1H), 2.55 (s, 3H), 2.45 (s, 3H), 2.40 (s, 3H); CI-MS: 306 (M+H).
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