1726
C. Keene, L. Kürti
FEATURE ARTICLE
J1 = 7.7 Hz, 1 H), 5.0 (d, J1 = 8 Hz, 1 H), 3.66 (dd, J1 = 16.7 Hz,
J2 = 9.3 Hz, 1 H), 3.12 (d, J1 = 16 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 149.09, 138.11, 133.97, 133.60,
133.58, 132.06, 131.97, 130.17, 129.50, 128.85, 127.66, 127.33,
127.19, 126.88 (q, J1 = 5.9 Hz), 36.71, 34.20, 29.64.
3l
Reaction was carried out with 1 (10 mmol) and nitrostyrene 2l (5
mmol); yield: 891 mg (42%); yellow solid; mp 225–245 °C;
Rf = 0.25 (10% EtOAc–hexanes).
IR (ATR): 1508, 1314, 758 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.13–7.97 (m, 1 H), 7.50–7.19 [m,
5 (7) H], 7.17–7.03 (m, 4 H), 6.91 (d, J1 = 3.4 Hz, 1 H), 4.81 (dd,
J1 = 8.8 Hz, J2 = 6.4 Hz, 1 H), 4.56–4.35 (m, 2 H), 3.70–3.50 (m, 1
H), 3.19–2.99 (m, 2 H), 1.31–0.95 [m, 6 (8) H].
13C NMR (100 MHz, CDCl3): δ = 149.67, 140.72, 140.65, 139.21,
139.15, 138.40, 136.04, 134.64, 134.61, 132.21, 132.14, 132.11,
131.85, 131.82, 131.79, 130.13, 130.10, 130.05, 129.63, 129.60,
129.57, 128.69, 128.02, 128.00, 127.73, 127.71, 127.59, 127.46,
127.43, 127.40, 127.27, 127.24, 127.17, 127.12, 127.04, 57.01,
51.00, 45.14, 37.78, 37.71, 37.64, 36.77, 36.68, 30.07, 30.04, 29.98.
HRMS (ESI): m/z calcd for C17H12F3NO2 + Na (M + Na)+:
342.0712; found: 342.0697.
3h
Reaction was carried out on a 25 mmol scale; yield: 2.06 g (56%);
yellow crystalline solid; mp 91.0–93.5 °C; Rf = 0.2 (5% EtOAc–
hexanes).
IR (ATR): 1692, 1643, 1599, 1523, 1495, 1355, 1312, 1186 cm–1.
1H NMR (400 MHz, CDCl3): δ = 8.22 (s, 1 H), 8.00–7.88 (m, 1 H),
7.47 (dd, J1 = 7.2 Hz, J2 = 1.9 Hz, 1 H), 7.41–7.28 (m, 4 H), 7.14 (d,
J1 = 7.0 Hz, 1 H), 7.01–6.96 (m, 1 H), 5.17 (d, J1 = 9.5 Hz, 1 H),
3.74 (dd, J1 = 16.9 Hz, J2 = 9.4 Hz, 1 H), 3.30 (d, J1 = 17.0 Hz, 1 H).
HRMS (ESI): m/z calcd for C26H20N2O4 + Na (M + Na)+: 447.1315;
found: 447.1326.
13C NMR (100 MHz, CDCl3): δ = 148.47, 134.28, 134.23, 134.02,
134.00, 133.16, 132.33, 130.43, 129.37, 128.93, 128.27, 127.86,
127.80, 125.39, 36.02, 33.25.
HRMS (ESI): m/z calcd for C16H12N2O4 + Na (M + Na+): 319.0689:
found: 319.0677.
Radical Bromination of Cyclic Nitrostyrenes 3 To Form 3-Sub-
stituted 2-Nitronaphthalenes 4a–l; General Procedure
A 100 mL round-bottom flask, equipped with a magnetic stir bar,
was charged with the respective cyclic nitrostyrene 3 (10 mmol, 1
equiv), benzoyl peroxide (370 mg, 15 mol%), NBS (3.03 g, 17
mmol, 1.7 equiv), and 1,2-dichloroethane (67 mL). The resulting
solution was then kept at reflux for the indicated amount of time
(Table 2). Once the starting material was consumed, the reaction
mixture was cooled to r.t., diluted with CH2Cl2 (60 mL), and poured
into a separatory funnel. Next, 20% aq Na2S2O3 (100 mL) was add-
ed to neutralize the Br2 generated during the reaction. The aqueous
phase was then extracted with CH2Cl2 (3 × 100 mL) and the com-
bined organic layers were dried (MgSO4). The solvent was removed
in vacuo and the crude product was purified by column chromatog-
raphy with EtOAc–hexanes as eluent.
3i
Reaction was carried out on a 20 mmol scale; yield: 2.33 g (54%);
yellow oil; Rf = 0.35 (5% EtOAc–hexanes).
IR (thin film): 1547, 1514, 1454, 1366, 1302 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.90 (s, 1 H), 7.35–7.28 (m, 3 H),
7.26–7.19 (m, 2 H), 3.23–3.15 (m, 2 H), 3.11–3.03 (m, 1 H), 1.85
(td, J1 = 6.9 Hz, J2 = 5.9 Hz, 1 H), 0.92 (d, J1 = 6.9 Hz, 3 H), 0.76
(d, J1 = 6.8 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 151.17, 136.47, 131.33, 131.30,
129.86, 129.80, 127.92, 127.06, 37.78, 30.63, 30.13, 20.24, 19.17.
4a
Reaction was carried out on a 20 mmol scale; yield: 4.98 g (99%);
3j
yellow solid; mp 90.0–93.5 °C; Rf = 0.22 (5% EtOAc–hexanes).
IR (ATR): 1595, 1522, 1501, 1450, 1348, 1315, 895 cm–1.
Reaction was carried out on a 20 mmol scale; yield: 2.45 g (57%);
yellow crystalline solid; mp 57.9–59.3 °C; Rf = 0.35 (5% EtOAc–
hexanes).
1H NMR (400 MHz, CDCl3): δ = 8.42 (s, 1 H), 7.98 (dd, J1 = 8.2 Hz,
J2 = 1.4 Hz, 1 H), 7.91 (dd, J1 = 8.2 Hz, J2 = 1.4 Hz, 1 H), 7.88 (s, 1
H), 7.70–7.61 (m, 2 H), 7.51–7.40 (m, 5 H).
13C NMR (100 MHz, CDCl3): δ = 147.35, 137.68, 134.26, 132.77,
131.25, 131.03, 129.32, 128.77, 128.55, 127.97, 127.89, 127.86,
127.80, 124.51.
IR (ATR): 1638, 1501, 1468, 1454, 1308, 1204 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.87 (s, 1 H), 7.33–7.25 (m, 2 H),
7.20 (dd, J1 = 13.2 Hz, J2 = 7.3 Hz, 2 H), 3.31–3.22 (m, 2 H), 3.15
(d, J = 15.5 Hz, 1 H), 0.78 (s, 9 H).
13C NMR (100 MHz, CDCl3): δ = 150.40, 137.41, 131.84, 131.27,
129.87, 129.45, 127.32, 126.88, 39.85, 36.84, 30.76, 27.37.
HRMS (ESI): m/z calcd for C14H17NO2 + Na (M + Na)+: 254.1152;
found: 254.1138.
HRMS (ESI): m/z calcd for C16H11NO2 + Na (M + Na)+: 272.0682;
found: 272.0654.
4b
Reaction was carried out on a 7 mmol scale; yield: 2.07 g (99%);
3k
yellow solid; mp 144.5–155.4 °C; Rf = 0.22 (5% EtOAc–hexanes).
IR (ATR): 1528, 1501, 1423, 1366, 1333 cm–1.
Reaction was carried out with 1 (9 mmol) and pentafluoronitrosty-
rene 2k (6.83 mmol); yield: 1.13 g (57%); yellow crystalline solid;
mp 179.8–188.1 °C; Rf = 0.3 (15% EtOAc–hexanes).
1H NMR (400 MHz, CDCl3): δ = 8.68 (d, J1 = 11.1 Hz, 1 H), 8.37
(d, J1 = 8.5 Hz, 1 H), 8.08 (d, J1 = 7.4 Hz, 1 H), 7.96–7.85 (m, 3 H),
7.75–7.67 (m, 2 H), 7.64–7.37 (m, 4 H), 7.30 (d, J1 = 7.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 147.74, 147.32, 136.46, 136.14,
135.86, 134.50, 134.47, 133.05, 132.48, 131.82, 131.78, 131.54,
131.46, 131.44, 130.59, 130.10, 129.82, 129.60, 129.33, 129.16,
129.08, 128.40, 128.38, 128.22, 127.99, 127.89, 127.87, 127.63,
127.36, 127.27, 126.67, 126.48, 126.46, 125.93, 125.49, 125.22,
125.07, 124.85, 124.78, 123.15.
IR (ATR): 1688, 1506, 1479, 1452, 1319, 1198, 1001 cm–1.
1H NMR (400 MHz, CDCl3): δ = 10.27 (s, 1 H), 8.08 (s, 1 H), 7.83
(dd, J1 = 7.6 Hz, J2 = 1.7 Hz, 1 H), 7.52–7.38 (m, 4 H), 7.33 (t,
J1 = 7.4 Hz, 1 H), 7.18 (d, J1 = 7.5 Hz, 1 H), 7.06 (d, J1 = 7.6 Hz, 1
H), 4.99 (dd, J1 = 9.7 Hz, J2 = 5.0 Hz, 1 H), 4.55 (s, 2 H), 3.60 (dd,
J1 = 16.8 Hz, J2 = 9.6 Hz, 1 H), 3.20 (dd, J1 = 16.8 Hz, J2 = 4.9 Hz,
1 H).
13C NMR (100 MHz, CDCl3): δ = 192.80, 145.85, 138.89, 134.18,
134.13, 134.12, 133.95, 133.93, 133.53, 132.08, 130.60, 129.65,
129.40, 127.75, 127.34, 34.94, 29.48, 25.10.
HRMS (ESI): m/z calcd for C20H13NO2 + Na (M + Na)+: 322.0839;
found: 322.0822.
HRMS (ESI): m/z calcd for C24H15F4NO3 + Na (M + Na)+:
464.0880; found: 464.0880.
4c
Reaction was carried out on a 10 mmol scale; yield: 2.07 g (74%);
yellow solid; mp 115.0–116.0 °C; Rf = 0.2 (5% EtOAc–hexanes).
Synthesis 2013, 45, 1719–1729
© Georg Thieme Verlag Stuttgart · New York