Molecules 2018, 23, 2363
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for 10 min. Then, benzoyl chloride (1.7 mL, 14.75 mmol) was added slowly, and stirring was continued
for 30 min. The ice bath was removed, and the mixture was allowed to warm to r.t., then quenched by
pouring it into water. The aqueous and organic layers were separated, and the aqueous phase was
extracted with dichloromethane (3
×
10 mL). The combined organic phase was washed with 0.5 M
HCl, 0.5 M aqeouse solution of NaHCO3 and brine, dried over sodium sulfate, filtered, and evaporated
under reduced pressure to give a yellow liquid. The crude product was purified by open column
chromatography (ethyl acetate) to afford 3a as a transparent yellow liquid (1.5530, 8.86 mmol, 73%).
1H-NMR (400 MHz, CDCl3),
δ (ppm): 7.504–7.356 (m, 5H), 3.615 (t, J = 6.8 Hz, 2H), 3.381 (t, J = 6.6 Hz,
2H), 1.929–1.804 (m, 4H). 13C-NMR (100 MHz, CDCl3), δ (ppm): 169.35, 137.10, 129.51, 128.00, 126.86,
49.33, 45.93, 26.17, 24.21. HRMS (ESI-TOF) m/z: [M + Na]+ Calcd. for C11H13NNaO+: 198.0890. Found:
198.0872. Anal. Calcd. for C11H13NO: C, 75.40; H, 7.48; N, 7.99. Found: C, 75.21; H, 7.63; N, 7.97.
N-(p-Chlorobenzoyl)pyrrolidine (3b). Pyrrolidine (0.5 mL, 6.1 mmol) was dissolved in dry CH2Cl2
◦
(3 mL) and the solution was cooled to 0 C. DIPEA (1.7 mL, 7.7 mmol) was added, and the mixture was
stirred for 10 min. Then, 4-chlorobenzoyl chloride (1.6164 mL, 7.4 mmol) dissolved in CH2Cl2 (2 mL)
was added slowly, and stirring was continued for 1 h. The ice bath was removed, and the mixture was
allowed to warm to r.t., then quenched by pouring it into water. The aqueous and organic layers were
separated, and the aqueous phase was extracted with dichloromethane (3
×
10 mL). The combined
organic phase was washed with 0.5 M HCl, 0.5 M aq. NaHCO3 and brine, dried over sodium sulfate,
filtered, and evaporated under reduced pressure to afford a transparent oil. The crude product was
purified by open column chromatography (hexane/ethyl acetate) to provide 3b as a white amorphous
◦
1
solid (444 mg, 2.1 mmol, 35%). m.p.: 62–64 C. H-NMR (400 MHz, CDCl3),
δ (ppm): 7.410 (dd;
J = 4.3 Hz, 1.8 Hz; 2H), 7. 307 (dd; J = 8.8 Hz, 2 Hz; 2H), 3.569 (t, J = 6.6 Hz, 2H), 3.349 (t, J = 6.6 Hz, 2H),
1.930–1.786 (m, 4H). 13C-NMR (100 MHz, CDCl3),
δ (ppm): 168.48, 135.73, 135.50, 128.63, 128.44, 49.55,
46.25, 26.36, 24.36. HRMS (ESI-TOF): [M + Na]+ Calcd. for C11H12ClNNaO+: 232.0500. Found 232.0517.
Anal. Calcd. for C11H12ClNO: C, 63.01; H, 5.77; N, 6.68. Found: C, 62.95; H, 5.78; N, 6.51.
N-(p-Nitrobenzoyl)pyrrolidine (3c). Pyrrolidine (0.5 mL, 6.1 mmol) was dissolved in dry CH2Cl2
(5 mL) at 0 ◦C. DIPEA (1.7 mL, 7.7 mmol) was added to the solution, and the mixture was stirred for
10 min. Then, 4-nitrobenzoyl chloride (1.1301 g, 7.4 mmol) dissolved in CH2Cl2 (10 mL) was added
slowly, and stirring was continued for 1 h at 0 ◦C. The ice bath was removed, and the mixture was
allowed to warm to r.t., then quenched by pouring it into water. The aqueous and organic layers were
separated, and the aqueous phase was extracted with dichloromethane (3 × 30 mL). The combined
organic phase was washed with brine, dried over sodium sulfate, filtered, and evaporated under
reduced pressure to give a a yellow liquid. The crude product was purified by open column
chromatography (ethyl acetate/acetone 1:1) to afford 3c as a slightly yellow solid (821.6 mg, 3.7 mmol,
◦
61.3%). m.p.: 78–80 C. 1H-NMR (400 MHz, CDCl3),
δ (ppm): 8.293–8.207 (m, 2H), 7.698–7.665 (m, 2H),
3.676 (t, J = 7.0 Hz, 2H), 3.382 (t, J = 6.6 Hz, 2H), 2.039–1.887 (m, 4H). 13C-NMR (100 MHz, CDCl3),
δ
(ppm): 167.61, 143.19, 128.29, 123.84, 49.61, 46.56, 26.52, 24.50. HRMS (ESI-TOF): [M + Na]+ Calcd. for
C11H12N2NaO3+: 244.0774. Found: 244.0742. Anal. Calcd. for C11H12N2O3: C, 59.99; H, 5.49; N, 12.72.
Found: C, 59.82; H, 5.45; N, 12.65.
N-(p-Toluoyl)pyrrolidine (3d)◦. Pyrrolidine (0.5 mL, 6.1 mmol) was dissolved in dry CH2Cl2 (5 mL)
and the solution was cooled to 0 C. DIPEA (1.7 mL, 7.7 mmol) was added, and the mixture was stirred
for 10 min. Then, a solution of p-tolyl chloride (975
and the mixture was stirred for 1 h at 0 C. The ice bath was removed, and the mixture was allowed to
warm to r.t., then quenched by pouring it into water. The aqueous and organic layers were separated,
µ
L, 7.4 mmol) in CH2Cl2 (10 mL) was slowly added,
◦
and the aqueous phase was extracted with dichloromethane (3
×
30 mL). The combined organic
phase was washed with brine, dried over sodium sulfate, filtered, and evaporated under reduced
pressure to provide a yellow liquid. The crude product was purified by open column chromatography
(hexane/ethyl acetate 4:1) to afford 3d as a white solid (654.4 mg, 3.5 mmol, 56.8%). M.p.: 75–76 ◦C.
1H-NMR (400 MHz, CDCl3),
δ
(ppm): 7.438–7.408 (m, 2H), 7.202–7.179 (m, 2H), 3.639 (t, J = 7.0 Hz,
2H), 3.439 (t, J = 6.6 Hz, 2H), 2.372 (s, 3H), 1.986–1.829 (m, 4H). 13C-NMR (100 MHz, CDCl3),
δ
(ppm):