Yield:63794-75-2 45%

Reaction Conditions:

with tartaric acid in water;1,2-dichloro-ethane at 80; for 1 h;

Steps:

Racemic 2-(1H-pyrrol-1-yl)butanoic acid (1h)

A solution of racemic 2-aminobutanoic acid (1.03 g, 10.0 mmol), racemic tartaric acid (1.51 g, 10.0 mmol), and 1,3-dimethoxytetrahydrofuran (1.28 mL, 10.0 mmol) in 1,2-dichloroethane (15 mL) and water (10 mL) was heated for 1 h at 80 °C. The reaction mixture was cooled to room temperature, and then filtered. The filtrate was diluted with water, and it was extracted with chloroform, and the organic layer was dried over sodium sulfate. After filtration of the mixture and evaporation of the solvent, the crude product was purified by column chromatography on neutral silica (ethyl acetate/hexane = 1/9). The product was stored overnight at -5 °C to afford 1h (687 mg, 45% yield) as a pale yellow solid; Mp: 123-125 °C (hexane); IR (KBr): 2978, 2939, 2877, 1720, 1550, 1489, 1095, 833, 725 cm-1; 1H NMR (CDCl3): δ 10.58 (br s, 1H, CO2H), 6.88-6.57 (m, 2H, pyrrole), 6.25-6.07 (m, 2H, pyrrole), 4.46 (dd, J = 9.6, 6.0 Hz, 1H, 2-H), 2.27-1.89 (m, 2H, 3-CH2), 0.88 (t, J = 7.2 Hz, 3H, 4-CH3); 13C NMR (CDCl3): δ 176.9 (1), 120.0 (pyrrole), 108.6 (pyrrole), 63.1 (2), 25.8 (3), 10.3 (4); HR MS: calcd for C8H11NO2Na (M + Na+) 176.0682, found 176.0675.

References:

Tokumaru, Eri;Tengeiji, Atsushi;Nakahara, Takayoshi;Shiina, Isamu [Chemistry Letters,2015,vol. 44,# 12,p. 1768 - 1770] Location in patent:supporting information