C([BH3-])#N.[Na+].C(#N)C.[C:8]([C:10]1[CH:26]=[CH:25][C:13]([C:14]([C:16]2[N:24]3[C:19]([CH:20]=[CH:21][CH:22]=[CH:23]3)=[CH:18][CH:17]=2)=O)=[CH:12][CH:11]=1)#[N:9].C(OCC)(=O)C>CCCCCC>[C:8]([C:10]1[CH:11]=[CH:12][C:13]([CH2:14][C:16]2[N:24]3[C:19]([CH:20]=[CH:21][CH:22]=[CH:23]3)=[CH:18][CH:17]=2)=[CH:25][CH:26]=1)#[N:9]
Sodium cyanoborohydride (0.32 grams, 5.06 mmol) was added in portions to an acetonitrile (15 mL) solution of 3-(4-cyanobenzoyl)indolizine (13) (0.19 grams, 0.84 mmol) and chlorotrimethylsilanen (0.65 mL, 5.06 mmol) cooled in an ice-bath. The reaction mixture was stirred at room temperature for 4 hours. It was then quenched with aqueous sodium bicarbonate solution, extracted with ethyl acetate (3×25 mL). The combined organic layers were washed with water, dried over sodium sulfate and concentrated in vacuo to give an oily residue, which was applied to the flash column chromatography using 10% ethyl acetate in hexane (Rf 0.3) to afford 3-(4-cyanobenzyl)indolizine (14) (0.11 grams, 56% yield). 1H NMR (CDCl3) δ 4.09 (s, 2H), 6.36 (m, 2H), 6.56 (m, 2H), 7.15 (d, J=8.4, 2H), 7.32 (d, J=9.3, 1H), 7.45 (m, 3H). ESMS calcd (C16H12N2): 232.1. found: 233.1 (M+H)+.
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