Cl.[NH2:2][CH2:3][C:4]([O:6][CH2:7][CH3:8])=[O:5].[CH:9]1([C:14](=O)[CH2:15][CH2:16][C:17](=O)[CH3:18])[CH2:13][CH2:12][CH2:11][CH2:10]1.C(=O)(O)[O-].[Na+]>ClCCl.O>[CH:9]1([C:14]2[N:2]([CH2:3][C:4]([O:6][CH2:7][CH3:8])=[O:5])[C:17]([CH3:18])=[CH:16][CH:15]=2)[CH2:13][CH2:12][CH2:11][CH2:10]1A slurry of ethyl 2-aminoacetate hydrochloride (2.93 g, 21.0 mmol), 1-cyclopentylpentane-1,4-dione (3.43 g, 20.4 mmol), and sodium bicarbonate (4.28 g, 51.0 mmol) in dichloromethane (20.4 mL) was heated at 50° C. for 72 hours, after which the reaction was diluted in water and extracted with dichloromethane (3×30 mL), dried (sodium sulfate), filtered and concentrated to a gold residue. Purification by silica gel chromatography (ISCO 120 g, 20 mL/min) using 0 to 35% ethyl acetate in hexanes afforded ethyl 2-(2-cyclopentyl-5-methyl-1H-pyrrol-1-yl)acetate (3.49 g, 14.8 mmol, 73% yield) as a clear colorless liquid. 1H NMR (400 MHz, CDCl3) δ (ppm): 5.84 (s, 2H, two shifts isochronous), 4.54 (s, 2H), 4.23 (q, 2H), 2.83 (m, 1H), 2.19 (s, 3H), 1.91-1.98 (m, 2H), 1.73-1.79 (m, 2H), 1.58-1.64 (m, 4H), 1.27 (t, 3H).
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