Chaperon Effect on the Nitration of Aromatics
J . Org. Chem., Vol. 63, No. 4, 1998 957
(b) Dilu ted System . A solution of 100% commercial HNO3
(50 mmol) in CH2Cl2 (7.7 mL) was added dropwise to a solution
of the aromatic substrate (5.0 mmol, Table 1) in CH2Cl2 (25
mL) under vigorous stirring at 0 °C. The mixture was then
stirred 24 h at room temperature and, after this time, washed
with 10% aqueous Na2SO4 and treated in the usual way.
Meth yl 2-n itr oben zen ea ceta te (2a ), m eth yl 4-n itr oben -
zen ea ceta te (2c), eth yl 2-n itr oben zen ea ceta te (3a ), and
eth yl 4-n itr oben zen ea ceta te (3c) have been described
previously.2d
1-(2-Meth ylp r op yl)-2-n itr oben zen e (11a ). Yellow oil: bp
129 °C/2400 Pa;26a IR (film) 2960s, 2870m, 1609w, 1577w,
1527s, 1467m, 1386w, 1348s, 1165w, 862m, 785m, 735s, 702w,
668m cm-1; 1H NMR δ 0.92 (d, J ) 6.6 Hz, 6H), 1.91 (app nn,
1H), 2.79 (d, J ) 7.1 Hz, 2H), 7.26-7.39 (m, 2H), 7.50 (pseudo
td, J o ) J o′ ) 7.5 Hz, J m ) 1.4 Hz, 1H), 7.86 (dd, J o ) 7.9 Hz,
J m ) 1.3 Hz, 1H); 13C NMR δ 149.81, 136.28, 132.64, 132.30,
126.88, 124.52, 41.65, 29.48, 22.39; MS m/z 120 (100), 92 (80),
43 (75), 65 (57), 41 (45), 179 (M+, <1).
(pseudo td, J o ) J o′ ) 7.5 Hz, J m ) 1.5 Hz, 1H), 8.07 (ddd, J o
) 8.0 Hz, J m ) 1.5 Hz, J p ) 0.3 Hz, 1H); 13C NMR δ 169.21,
148.60, 133.33, 133.14, 129.81, 128.29, 124.92, 68.58, 39.87,
21.45; MS m/z 43 (100), 120 (78), 41 (58), 92 (37), 78 (36), 223
(M+, <1).
1-Meth yleth yl 4-Nitr oben zen ea ceta te (4c). Pale yellow
crystals: mp 36 °C;32 IR (pellet) 2987w, 1730s, 1607w, 1518s,
1467w, 1351s, 1229m, 1189m, 1104s, 905w, 856w, 836w, 798w,
1
723s cm-1; H NMR δ 1.24 (d, J ) 6.3 Hz, 6H), 3.70 (s, 2H),
5.03 (sp, J ) 6.3 Hz, 1H), 7.42-7.51 (m, 2H), 8.15-8.23 (m,
2H); 13C NMR δ 169.65, 147.14, 141.63, 130.20, 123.69, 68.92,
41.38, 21.70; MS m/z 43 (100), 137 (21), 136 (15), 41 (13), 89
(11), 223 (M+, <1).
N,N-Dim eth yl-2-n itr oben zen ea ceta m id e (12a ). Pale
yellow crystals: mp 73 °C;33 IR (pellet) 2935m, 1655s, 1612w,
1578w, 1522s, 1389m, 1345s, 1134s, 864m, 794m, 739s, 696w,
1
593m, 493w cm-1; H NMR δ 2.98 (s, 3H), 3.14 (s, 3H), 4.06
(s, 2H), 7.32 (app d, J app ) 7.5 Hz, 1H), 7.43 (pseudo td, J o
)
J o′ ) 7.7 Hz, J m ) 1.6 Hz, 1H), 7.57 (pseudo td, J o ) J o′ ) 7.5
Hz, J m ) 1.4 Hz, 1H), 8.08 (dd, J o ) 8.0 Hz, J m ) 1.3 Hz, 1H);
13C NMR δ 168.98, 149.00, 133.19 (2C), 131.39, 127.97, 124.96,
38.71, 37.29, 35.57; MS.33b
1-(2-Meth ylp r op yl)-4-n itr oben zen e (11c). Pale yellow
oil: bp 141 °C/2400 Pa;26 IR (film) 2959s, 2871w, 1606m,
1599m, 1519s, 1467w, 1346s, 1110w, 858m, 799w, 743m, 698w
1
cm-1; H NMR δ 0.92 (d, J ) 6.6 Hz, 6H), 1.92 (app nn, 1H),
N,N-Dim eth yl-4-n itr oben zen ea ceta m id e (12c). Pale
yellow crystals: mp 87 °C;33c IR (pellet) 2933w, 1649s, 1604w,
1513s, 1396w, 1350s, 1264w, 1135m, 1110w, 858w, 818m,
2.59 (d, J ) 7.2 Hz, 2H), 7.24-7.35 (m, 2H), 8.09-8.20 (m,
2H); 13C NMR δ 149.60, 133.97, 129.78, 123.39, 45.16, 30.11,
22.22; MS m/z 43 (100), 137 (99), 41 (67), 90 (54), 107 (51),
179 (M+, 49).
1
799w, 740s, 694w cm-1; H NMR δ 2.99 (s, 3H), 3.07 (s, 3H),
3.82 (s, 2H), 7.38-7.50 (m, 2H), 8.12-8.23 (m, 2H); 13C NMR
δ 169.35, 146.79, 142.74, 130.02, 123.56, 40.15, 37.51, 35.60;
MS.34
r-Met h yl-2-n it r ob en zen ea cet ic Acid (10a ). White
solid: mp 108 °C;27 IR and 1H NMR;28 13C NMR δ 179.35,
148.66, 134.45, 133.45, 129.93, 128.28, 124.96, 41.43, 17.39;
MS m/z 77 (100), 43 (91), 150 (54), 103 (53), 149 (50), 195 (M+,
4).
2-Nitr oben zen ep r op a n en itr ile (16a ). Yellowish crys-
tals: mp 39 °C;35 IR (neat) 2249w, 1611w, 1577w, 1525s, 1349s,
1077w, 858m, 813w, 791m, 743s, 700m, 664w, 605w, 530m
1
cm-1; H NMR δ 2.85 (t, J ) 7.1 Hz, 2H), 3.24 (t, J ) 7.1 Hz,
2-Nitr oben zen ep r op a n oic Acid (8a ). Pale yellow crys-
tals: mp 113 °C;29 IR (pellet) 2923s (broad), 1701s, 1520s,
1436m, 1342s, 1273w, 1221m, 934w, 861m, 792w, 729m, 699w
2H), 7.44-7.55 (m, 2H), 7.65 (pseudo td, J o ) J o′ ) 7.5 Hz, J m
) 1.4 Hz, 1H), 8.04 (dd, J o ) 8.1 Hz, J m ) 1.6 Hz, 1H); 13C
NMR δ 148.55, 133.68, 132.84, 132.46, 128.53, 125.14, 118.55,
29.16, 18.20; MS m/z 77 (100), 78 (88), 92 (59), 103 (53), 51
(49), 176 (M+, 2).
1
cm-1; H NMR δ 2.80 (t, J ) 7.7 Hz, 2H), 3.23 (t, J ) 7.6 Hz,
2H), 7.38-7.46 (m, 2H), 7.50-7.62 (m, 1H), 7.91-7.99 (m, 1H),
11.09 (broad s, 1H); 13C NMR δ 178.78, 149.14, 135.16, 133.30,
132.07, 127.72, 124.95, 34.54, 27.96; MS m/z 149 (100), 77 (88),
135 (66), 91 (43), 79 (42), 195 (M+, 16).
4-Nitr oben zen ep r op a n en itr ile (16c). White crystals:
mp 79 °C;36 IR (pellet) 2243w, 1599w, 1515s, 1344s, 1178w,
1104m, 1015w, 937w, 858s, 806m, 748m, 699m, 653w, 518m,
499s cm-1; 1H NMR δ 2.72 (t, J ) 7.1 Hz, 2H), 3.09 (t, J ) 7.1
Hz, 2H) 7.40-7.48 (m, 2H), 8.17-8.25 (m, 2H); 13C NMR δ
147.16, 145.22, 129.28, 124.02, 118.28, 31.09, 18.74; MS m/z
136 (100), 77 (40), 106 (39), 103 (36), 176 (M+, 34).
4-Nitr oben zen ep r op a n oic Acid (8c). White needles: mp
165 °C;29 IR (pellet) 2920s (broad), 1701s, 1605w, 1596w,
1517s, 1436m, 1344s, 1220m, 1188w, 1111w, 934w, 859m,
732m, 693w cm-1; 1H NMR (CDCl3/CD3COCD3 7/3 v/v) δ 2.72
(t, J ) 7.5 Hz, 2H), 3.09 (t, J ) 7.5 Hz, 2H), 7.41-7.52 (m,
2H), 8.09-8.21 (m, 2H); 13C NMR (CDCl3/CD3COCD3 7/3 v/v)
δ 172.93, 148.15, 146.02, 128.80, 122.98, 33.90, 29.94; MS30
m/z 149 (100), 77 (46), 195 (M+, 45), 106 (30), 107 (29).
2-Nitr oben zen ebu ta n oic Acid (9a ). Pale yellow crys-
tals: mp 70 °C;31 IR (pellet) 2962s (broad), 1705s, 1608w,
1575w, 1523s, 1420w, 1346s, 1292m, 1267m, 1220m, 918w,
858m, 789w, 761m, 723m, 668w cm-1; 1H NMR δ 2.02 (m, 2H),
2.47 (t, J ) 7.3 Hz, 2H), 2.96 (t, J ) 7.8 Hz, 2H), 7.30-7.43
(m, 2H), 7.48-7.59 (m, 1H), 7.87-7.95 (m, 1H), 10.57 (broad
s, 1H); 13C NMR δ 179.52, 149.27, 136.24, 133.01, 131.94,
127.29, 124.78, 33.43, 32.03, 25.40; MS m/z 132 (100), 162 (99),
92 (90), 146 (72), 91 (62), 209 (M+, <1).
1-(2-Nit r op h en yl)-2-p r op a n on e (17a ). Pale yellow
crystals: mp 27 °C;37 IR (neat, melted) 1723s, 1613w, 1579w,
1525s, 1411m, 1348s, 1162m, 869w, 789m, 732m, 699w, 673w,
631w cm-1; 1H NMR δ 2.30 (s, 3H), 4.13 (s, 2H), 7.27 (dd, J o
)
7.5 Hz, J m ) 1.2 Hz, 1H), 7.43 (pseudo td, J o ) J o′ ) 7.7 Hz,
J m ) 1.5 Hz, 1H), 7.58 (pseudo td, J o ) J o′ ) 7.5 Hz, J m ) 1.4
Hz, 1H), 8.08 (dd, J o ) 8.1 Hz, J m ) 1.2 Hz, 1H); 13C NMR δ
203.51, 148.37, 133.48, 133.37, 130.18, 128.22, 124.93, 48.34,
29.76; MS.38
2-(2-Nit r op h en yl)-1-p h en ylet h a n on e (18a ). Yellow
crystals: mp 72 °C; IR;39 1H NMR δ 4.69 (s, 2H), 7.33 (dd, J o
) 7.5 Hz, J m ) 1.4 Hz, 1H), 7.41-7.65 (m, 5H), 7.97-8.07 (m,
2H), 8.13 (dd, J o ) 8.0 Hz, J m ) 1.4 Hz, 1H); 13C NMR δ 195.29,
148.95, 136.37, 133.58, 133.46, 133.41, 130.57, 128.66, 128.32,
128.15, 125.17, 44.07; MS m/z 105 (100), 77 (64), 106 (15), 51
(8), 78 (7).
1-Meth yleth yl 2-Nitr oben zen ea ceta te (4a ). Pale yellow
liquid: bp 124 °C/67 Pa; IR (neat) 2983m, 2937w, 1732s,
1614w, 1581w, 1528s, 1467w, 1414w, 1349s, 1289w, 1255w,
1220m, 1181m, 1146w, 1108s, 958w, 842m, 789m, 718s cm-1
;
1H NMR δ 1.22 (d, J ) 6.3 Hz, 6H), 3.98 (s, 2H), 5.02 (sp, J )
6.3 Hz, 1H), 7.31-7.38 (m, 1H), 7.39-7.49 (m, 1H), 7.58
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