[CH3:1][C:2]1[N:7]2[CH:8]=[N:9][CH:10]=[C:6]2[CH:5]=[CH:4][CH:3]=1.CN(C)CCN(C)C.C([Li])CCC.Br[CH2:25][CH2:26][CH2:27][CH2:28][C:29]#[N:30]>O1CCCC1.CCCCCC>[C:29]([CH2:28][CH2:27][CH2:26][CH2:25][CH2:1][C:2]1[N:7]2[CH:8]=[N:9][CH:10]=[C:6]2[CH:5]=[CH:4][CH:3]=1)#[N:30]
A solution of 5-methylimidazo[1,5-a]pyridine (4.0 g) and tetramethylethylene diamine (4.9 g) in 100 ml of tetrahydrofuran is cooled to 0° under nitrogen and 26.5 ml of 1.6 N n-butyllithium in hexane is added dropwise maintaining the temperature below 2°. After 30 minutes this solution is transferred under nitrogen over 45 minutes to an ice-cold solution of 5-bromovaleronitrile (4.86 g) in 80 ml of tetrahydrofuran. After 15 minutes the solvent is evaporated and the residue is partitioned between water and ethyl acetate. The organic phase is reextracted with 2 N hydrochloric acid (3×15 ml). Basification of the aqueous phase to pH=10 with 50% sodium hydroxide, extraction with ethyl acetate (2×75 ml), drying over magnesium sulfate, evaporation and chromatography (SiO2, ethyl acetate) yields 5-(5-cyanopentyl)-imidazo[1,5-a]pyridine.
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