Ethyl 3-(nitromethyl)hexanoate (0.52 g, 1.1 eq, 2.55 mmol) is dissolved in absolute methanol (8 ml). Then 10% Pd/C (0.2 g) and ammonium formate (1 g) are added under vigorous stirring. After 15 min, the mixture is diluted with ether (100 ml) and filtered. The solid on the filter is washed with ether (2×50 ml). A solution of aldehyde x255 (0.7 g, 1 eq, 2.3 mmol) in methanol (5 ml) is added immediately. The combined solution is evaporated in the vacuum of a rotary evaporator. The residue is dissolved in methanol (10 ml), CH(OMe)3 (0.5 ml) is added, and the obtained solution is stirred at room temperature for 16 h. An excess of NaBH4 (1 g in several small portions) is then added to the reaction solution under vigorous stirring for 20 min. The reaction mixture is evaporated in the vacuum of a rotary evaporator. The residue is partitioned between ethyl acetate and water. The organic phase is separated, dried with anhydrous sodium sulfate, and evaporated. The residue is dissolved in acetonitrile (10 ml), and the solution is refluxed for 24 h to complete the cyclization. The solvent is distilled off. The residue is purified by chromatography on silicagel (CCl4/MeCN) to afford 4-propyl-1-{[1-(triisopropylsilyl)-1H-pyrrolo[2,3-b]pyridin-5-yl]methyl}pyrrolidin-2-one x256.
