X.-y. Qin et al. / Journal of Molecular Structure 989 (2011) 10–19
11
-O
ether (3:1) as eluant, giving a colorless oil product (4.3 g, 86.1%).
O
O
O
20
½aꢀD = –143.2 (c = 1.00, CH2Cl2); IR (KBr) cmꢁ1:1521, 1350 (
m
N+
N
N
N
N
2
2
2
NO2), 1618 (m amide bond), 3406 (m OH), 1596, 1438, 862 (m ben-
R
R
R
zene ring), 1107, 1049 (m
CAC ring of pyrrolidine); 1H NMR (CDCl3):
N+
8.28 (d, 2H, J = 8.1 Hz, AArH), 7.71 (d, 2H, J = 8.4 Hz, AArH), 4.52 (d,
2H, ACH2), 3.82(s, 1H, AOH), 3.45 (m, 2H, ACH2), 2.12 (m, 2H,
ACH2), 1.88 (m, 2H, ACH2); 13C NMR d (CDCl3): 169.47, 148.47,
142.65, 128.16, 123.72, 65.70, 61.35, 50.94, 28.1, 24.93. Anal. Calcd.
for C12H14N2O4: C, 57.59; H, 5.64; N, 11.19. Found: C, 57.62; H,
-O
O
Scheme 1. The distribution of the unpaired spin density.
5.72; N, 11.09%. D-configuration product was synthesized by the
same method. ½aꢀD = +143.4 (c = 1.00, CH2Cl2).
absorption spectra were recorded on a Jasco V-570 UV/vis/NIR
spectrophotometer (Jasco, Japan). The EPR spectra were obtained
using a Bruker ESP 300E spectrometer on solutions of radicals dis-
solved in dichloromethane. Circular dichroism spectra were re-
corded on a JASCO-715 spectrometer. Magnetic susceptibility
measurements were obtained with a Quantum Design SQUID
magnetometer.
20
2.3. Synthesis of
(compound 2)
L-N-p-nitrobenzoylpyrrolidinylformaldehyde
To a reaction mixture of L-N-p-nitrobenzoylpyrrolidinylmetha-
nol (3.77 g, 15 mmol) and trichloroisocyanuric acid (TCCA, 3.7 g,
16 mmol), CH2Cl2 (40 ml) was added, and the reaction mixture
was stirred and maintained at 0 °C for 5 min, followed by addition
of TEMPO (0.025 g, 0.16 mmol). Then the mixture was warmed to
room temperature and stirred for 20 min and filtered on Celite.
The precipitate was washed with CH2Cl2 (10 ml ꢂ 2). The com-
bined organic phases were washed with 40 ml of a saturated solu-
tion of Na2CO3 and then by 0.1 N HCl (40 ml) and brine (40 ml). The
organic phase was dried over anhydrous Na2SO4, and stripped of
solvent. The crude product was purified by column chromatogra-
phy on silica gel using ethyl acetate/petroleum ether/triethylamine
(2:1:0.1) as eluant, giving the product as colorless liquid (3.25 g,
All chemical reagents were purchased from Nanjing Tianzun
Zezhong Chemical Limited Company (Nanjing, China). CH2Cl2 was
distilled from CaH2. The other chemical reagents were used with-
out further purification.
2.2. Synthesis of
1)
L-N-p-nitrobenzoylpyrrolidinylmethanol (compound
p-nitrobenzoyl chloride (4.0 g, 22.0 mmol), Et3N (2.23 g, 3.1 ml)
were added to in dry CH2Cl2 (50 ml) with vigorous stirring in an ice
bath. To this mixture, a solution of L-prolinol (2.0 g, 20 mmol) in
dry CH2Cl2 (20 ml) was added dropwise over a period of 20 min
at 0 °C. The mixture was warmed to room temperature and stirred
for 2 h. Then the reaction mixture was treated with water and ex-
tracted with CH2Cl2. The organic layer was dried over anhydrous
Na2SO4 and concentrated. The crude product was purified by col-
umn chromatography on silica gel using ethyl acetate/petroleum
20
86.3%). ½aꢀD = –64.8 (c = 1.00, CH2Cl2); IR (KBr) cmꢁ1: 1521, 1350
(m NO2), 1633 (m amide bond), 1731 (m CHO), 1598, 1423, 864 (m
benzene ring), 1107, 1014 (m
CAC ring of pyrrolidine); 1H NMR
(CDCl3): 9.68 (1H, ACHO), 8.29 (d, 2H, J = 6.0 Hz, AArH), 7.75 (d,
2H, J = 9.0 Hz, AArH), 4.71 (m, 1H, ACH), 3.57 (t, 2H, ACH2), 2.24
(m, 2H, ACH2), 2.03 (m, 2H, ACH2). 13C NMR d (CDCl3): 198.73,
CH2OH
CHO
N
CH2OH
N
C
N
Et3N
TEMPO(0.01 mol equiv)
H
+
Cl
2
1
O
C
O
CH2Cl2, r.t.
TCCA, CH2Cl2, r.t.
C
O
NO2
NO2
NHOH
NHOH
CH3OH
r.t.
3
NO2
OH
O
N
N
N
C
N
N
N
O
NaIO4, 0 0C
CH2Cl2
OH
O
C
O
4
5
NO2
D- and L-NNNBP
NO2
Scheme 2. Synthetic route of chiral nitronyl nitroxides.