[Br:1][C:2]1[CH:7]=[CH:6][C:5]([OH:8])=[CH:4][N:3]=1.[H-].[Na+].[CH:11]1(I)[CH2:15][CH2:14][CH2:13][CH2:12]1.O>CN(C=O)C>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([O:8][CH:11]2[CH2:15][CH2:14][CH2:13][CH2:12]2)=[CH:4][N:3]=12-Bromo-5-hydroxypyridine (3 mmol) is dissolved in DMF (10 ml) and NaH (1.4 eq., 60% suspension in liquid paraffin) is added. After 30 min cyclopentyl iodide (2.2 eq.) is added and the reaction solution is stirred 3 days at 120° C. The reaction solution is pored into water and extracted with methyl-tert.-butyl ether. The combined organic layers are dried over MgSO4 and the solvent is removed in vacuo. 2-Bromo-5-cyclopentyloxy-pyridine is obtained after column chromatography (heptane/ethylacetate) as yellow oil in a yield of 45%; HPLC (method C): 2.08 min; LC-MS (method A): 2.05 min, 241.95 (M+H+).
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