[Br:1][C:2]1[CH:3]=[C:4]2[N:10]=[C:9]([CH2:11][Cl:12])[NH:8][C:5]2=[N:6][CH:7]=1.[CH2:13]([P:17]([CH2:22][CH2:23][CH2:24][CH3:25])[CH2:18][CH2:19][CH2:20][CH3:21])[CH2:14][CH2:15][CH3:16]>CN(C)C=O.C(#N)C.[I-].C([N+](CCCC)(CCCC)CCCC)CCC>[Cl-:12].[Br:1][C:2]1[CH:3]=[C:4]2[N:10]=[C:9]([CH2:11][P+:17]([CH2:18][CH2:19][CH2:20][CH3:21])([CH2:22][CH2:23][CH2:24][CH3:25])[CH2:13][CH2:14][CH2:15][CH3:16])[NH:8][C:5]2=[N:6][CH:7]=1Alternatively, 4.0 g of 6-bromo-2-chloromethyl-3H-imidazo[4,5-b]pyridine (compound J1) are suspended in 17 ml of N,N-dimethylformamide and 54 ml of acetonitrile. 4.8 ml of tributylphosphine and 600 mg of tetrabutylammonium iodide are added sequentially at 40° C. Subsequently, the mixture is heated to 90° C. for 18 hours. The mixture is concentrated to dryness to give 8.94 g of the crude title compound as an oil, which is purified by chromatography on flash silica gel (eluent gradient: dichloromethane/5-20 vol. % 2-propanol). The remaining residue is re-dissolved in 150 ml of ethyl acetate. Upon standing at room temperature, a precipitate of the title compound is formed, which is collected by filtration and dried under high vacuum to yield 4.52 g of (6-bromo-3H-imidazo[4,5-b]pyridin-2-ylmethyl)-tributyl-phosphonium chloride as an amorphous solid of m.p. 180° C. ESI-MS: 412.5, 414.4 (M+, 100%:98%). TLC: Rf=0.45-0.55 (dichloromethane/methanol 10:1 parts by volume).
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