SPECIAL TOPIC
Pd-Catalyzed Reduction of Nitro Compounds to Amines
3335
(Z)-4-(4-Methoxyphenylamino)-4-oxobut-2-enoic Acid (Table 7,
entry 7)
J = 8.24 Hz, 1 H), 5.77 (s, 1 H), 5.42 (s, 1 H), 3.83 (s, 3 H), 2.00 (s,
3 H).
Bright yellow solid; yield: 211 mg (95%); mp 180 °C; Rf 0.3
(EtOAc–MeOH, 80:20); silica gel FC (hexanes–EtOAc, 50:50, then
0:100).
13C NMR (75 MHz, CDCl3): d = 166.8, 166.6, 140.5, 138.0, 130.7,
129.0, 125.3, 124.6, 121.0, 120.0, 52.1, 18.5.
LRMS (EI, 70 eV) m/z (%) = 219 (6), 151 (23), 135 (1), 120 (10),
IR (Nujol): 3256, 3061, 1713, 1633, 1539, 1508, 1468, 1412, 1280,
1248, 1176, 1035, 854, 825 cm–1.
1H NMR (300 MHz, DMSO-d6): d = 10.40 (s, 1H), 7.51 (d, J = 8.79
Hz, 2 H), 6.85 (d, J = 8.79 Hz, 2 H), 6.44 (d, J = 12.08 Hz, 1H), 6.25
(d, J = 12.08 Hz, 1 H), 3.66 (s, 3 H).
13C NMR (75 MHz, DMSO-d6): d = 166.8, 163.2, 156.1, 132.0,
131.4, 131.3, 121.5, 114.1, 55.3.
119 (5), 91 (10), 69 (100), 41 (75).
HRMS (EI): m/z calcd for C12H13NO3: 219.0895; found: 219.0893.
(E)-2-Bromo-4-(4-methoxyphenylamino)-4-oxobut-2-enoic
Acid and (E)-3-Bromo-4-(4-methoxyphenylamino)-4-oxobut-2-
enoic Acid (1:1.26) (Table 7, entry 13)
Yellow-brown solid; yield: 268 mg (89%); Rf 0.05 (EtOAc); silica
gel FC (hexanes–EtOAc, 50:50, then 0:100).
LRMS (EI, 70 eV): m/z (%) = 222 (1), 221 (11), 203 (27), 188 (12),
123 (69), 122 (44), 108 (100), 77 (8), 44 (6).
1H NMR (300 MHz, CDCl3 + DMSO-d6): d = 10.25 (s, 1 H, mea-
sured 0.56 H), 10.15 (s, 1 H, measured 0.44 H), 7.43 (d, J = 8.79 Hz,
2 H), 6.76 (d, J = 9.33 Hz, 2 H), 6.70 (s, 1 H, measured 0.44 H), 6.36
(s, 1 H, measured 0.56 H), 3.66 (s, 3 H).
13C NMR (75 MHz, CDCl3 + DMSO-d6): d = 163.5, 161.3, 155.7,
131.8, 131.3, 125.3, 121.1, 120.7, 113.6, 113.5, 106.8, 66.5, 54.9,
28.7, 23.4.
HRMS (EI): m/z calcd for C11H11NO4: 221.0688; found: 221.0684.
(Z)-4-(3-(Methoxycarbonyl)phenylamino)-4-oxobut-2-enoic
Acid (Table 7, entry 8)
White solid; yield: 209 mg (84%); mp 170 °C; Rf 0.05 (hexanes–
EtOAc, 50:50); silica gel FC (EtOAc–MeOH, 100:0, then 80:20).
2-Chloro-N-(4-methoxyphenyl)acetamide (Table 7, entry 14)
IR (Nujol): 3317, 3157, 2926, 2855, 1724, 1628, 1591, 1558, 1496,
1296, 1257, 1203, 1105, 1082, 968, 893, 846, 760, 609 cm–1.
1H NMR (300 MHz, CDCl3 + DMSO-d6): d = 10.90 (br s, 1 H), 8.11
(s, 1 H), 7.82 (d, J = 7.69 Hz, 1 H), 7.67 (d, J = 8.24 Hz, 1 H), 7.30
(dd, J = 7.69, 8.24 Hz, 1 H), 6.47 (d, J = 12.63 Hz, 1 H), 6.19 (d,
J = 12.63 Hz, 1 H), 3.73 (s, 3 H).
White solid; yield: 191 mg (96%); mp 117–119 °C; Rf 0.5 (hex-
anes–EtOAc, 50:50); silica gel FC (hexanes–EtOAc, 95:5, 80:20,
then 50:50).
IR (Nujol): 3294, 1674, 1545, 1512, 1466, 1414, 1300, 1248, 1180,
1030, 831, 788, 711, 688 cm–1.
13C NMR (75 MHz, CDCl3 + DMSO-d6): d = 165.8, 165.4, 163.9,
137.3, 133.3, 132.5, 130.2, 128.6, 125.6, 124.6, 120.9, 51.7.
1H NMR (300 MHz, CDCl3): d = 8.12 (br s, 1 H), 7.41 (d, J = 8.79
Hz, 2 H), 6.86 (d, J = 8.79 Hz, 2 H), 4.14 (s, 3 H), 3.77 (s, 3 H).
LRMS (EI, 70 eV): m/z (%) = 249 (6), 204 (5), 200 (36), 172 (20),
152 (11), 151 (51), 150 (71), 135 (1), 120 (45), 119 (70), 115 (10),
99 (12), 98 (18), 97 (10), 92 (100), 77 (5), 65 (16), 64 (32), 63 (16),
62 (15), 54 (26), 53 (36).
13C NMR (75 MHz, CDCl3): d = 163.6, 157.0, 129.6, 122.0, 114.2,
55.4, 42.8.
LRMS (EI, 70 eV): m/z (%) = 201 (16), 200 (4), 199 (50), 124 (14),
123 (32), 122 (64), 121 (43), 108 (100), 77 (10).
HRMS (EI): m/z calcd for C12H11NO5: 249.0637; found: 249.0633.
HRMS (EI): m/z calcd for C9H10ClNO2: 199.0400; found:
(Z)-4-(2,6-Dimethylphenylamino)-4-oxobut-2-enoic Acid
199.0397.
(Table 7, entry 9)
Methyl 3-(2-Chloroacetamido)benzoate (Table 7, entry 15)
White solid; yield: 63 mg (29%); mp 170–173 °C; Rf 0.05 (hex-
anes–EtOAc, 50:50); silica gel FC (EtOAc–MeOH, 100:0, then
80:20).
1H NMR (300 MHz, CDCl3 + DMSO-d6): d = 9.94 (s, 1 H), 6.53 (m,
3 H), 6.15 (d, J = 13.18 Hz, 1 H), 5.77 (d, J = 12.63 Hz, 1 H), 1.65
(s, 6 H).
Tan solid; yield: 190 mg (84%); mp 83 °C; Rf 0.5 (hexanes–EtOAc,
50:50); silica gel FC (hexanes–EtOAc, 95:5, 80:20, then 50:50).
IR (Nujol): 1732, 1668, 1408, 1244, 1084, 814, 754 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.59 (br s, 1 H), 8.03 (m, 1 H), 7.82
(dq, J = 1.09, 8.24 Hz, 1 H), 7.74 (dt, J = 1.09, 7.69 Hz, 1 H), 7.33
(dd, J = 7.69, 8.24 Hz, 1 H), 4.13 (s, 2 H), 3.82 (s, 3 H).
13C NMR (75 MHz, CDCl3): d = 166.4, 164.3, 136.9, 130.8, 129.1,
125.9, 124.5, 121.0, 52.1, 42.8.
13C NMR (75 MHz, CDCl3 + DMSO-d6): d = 163.9, 163.5, 133.6,
133.4, 131.6, 130.8, 126.8, 126.4, 17.0.
N-(4-Methoxyphenyl)methacrylamide (Table 7, entry 10)
LRMS (EI, 70 eV): m/z (%) = 229 (9), 228 (3), 227 (28), 178 (21),
150 (99), 120 (100), 92 (67), 91 (26), 77 (11), 76 (17), 59 (4).
White solid; yield: 189 mg (99%); mp 80 °C; Rf 0.5 (hexanes–
EtOAc, 50:50); silica gel FC (hexanes–EtOAc, 80:20, then 50:50).
1H NMR (300 MHz, CDCl3): d = 7.43 (s, 1 H), 7.43 (d, J = 8.79 Hz,
2 H), 6.83 (d, J = 8.79 Hz, 2 H), 5.75 (s, 1 H), 5.40 (s, 1 H), 3.76 (s,
3 H), 2.02 (s, 3 H).
HRMS (EI): m/z calcd for C10H10ClNO3: 227.0349; found:
227.0352.
2-Chloro-N-(2,6-dimethylphenyl)acetamide (Table 7, entry 16)
13C NMR (75 MHz, CDCl3): d = 166.6, 156.4, 140.6, 130.8, 121.9,
White-pink solid; isolated: 144 mg (<72%; product contaminated
with a small amount of an unknown material; mp 114–117 °C;
Rf 0.5 (hexanes–EtOAc, 50:50); silica gel FC (hexanes–EtOAc,
95:5, 80:20, then 50:50).
119.5, 114.0, 55.3, 18.6.
Methyl 3-Methacrylamidobenzoate (Table 7, entry 11)
Light yellow oil; yield: 207 mg (94%); Rf 0.5 (hexanes–EtOAc,
50:50); silica gel FC (hexanes–EtOAc, 95:5, 80:20, then 50:50).
IR (PTFE card, neat): 3254, 1662, 1533, 1177, 1142, 767 cm–1.
IR (Nujol): 3217, 1680, 1653, 1539, 1473, 1431, 1323, 1147, 979,
760, 707, 665 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.83 (br s, 1 H), 7.08 (m, 3 H), 4.22
(s, 2H), 2.21 (s, 6 H).
IR (neat): 3337, 2953, 1718, 1668, 1593, 1541, 1489, 1437, 1298,
1232, 1163, 1109, 929, 756 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.06 (t, J = 1.64 Hz, 1 H), 7.95 (br
s, 1 H), 7.89 (m, 1 H), 7.72 (dt, J = 1.64, 8.24 Hz, 1 H), 7.33 (t,
Synthesis 2006, No. 19, 3316–3340 © Thieme Stuttgart · New York