The Journal of Organic Chemistry
Article
a
Table 6. Control Reactions for the Electrochemical Amination of Phenylboronic Acid
b
product composition (%)
entry
1
anode− cathode
conditions
NH3(aq) (2.61 M), N2
1a
2a
3a
4a
5a
Cu−Cu
Pt−Pt
Pt−Pt
80
65
0
0
6
0
0
15
0
0
0
0
0
0
c
2
NH3(aq) (2.61 M)
25
d
e
e
e
,e
3
4
5
6
NH3(aq) (2.61 M), Cu2O (30 mmol %)
NH3(aq) (2.61 M), Cu2O (30 mmol %)
NH3(aq) (2.61 M), Cu powder (60 mmol %)
NH3(aq) (2.61 M), CuSO4 (60 mmol %)
20
10
5
70
44
50
15
trace
18
20
15
35
20
15
25
a
b
1
Phenylboronic acid (1.0 mmol) in satd aq KNO3 (8 mL) with 25% aqueous ammonia. The product composition was determined by H NMR
c
spectroscopy. The yield of benzene was determined by GC analysis. The solution was electrolyzed at a constant potential of 0.2 V vs Ag/AgCl in an
d
undivided cell. Two platinum foils (1.5 cm2). The solution was electrolyzed at a constant potential of 0.2 V vs Ag/AgCl in a divided cell with a salt
bridge connecting the anode chamber and the cathode chamber. Anode chamber: phenylboronic acid (1.0 mmol) in satd aq KNO3 (8 mL), 25%
e
aqueous ammonia. Cathode chamber: satd aq KNO3 (10 mL). Two platinum foils (1.5 cm2). Phenylboronic acid was added after the copper
catalyst was dissolved in the ammonia solution.
7.21 (s, 1 H), 7.55 (d, J = 8.8 Hz, 2 H); δC (100 MHz, CDCl3, Me4Si)
102.8, 116.7, 119.5, 134.5, 160.7.
2 H), 7.40 (d, J = 7.2 Hz, 2 H); δC (100 MHz, CDCl3, Me4Si) 100.1,
114.6, 120.3, 133.9, 150.6.
Data for 3-nitrophenol (2c):4g yield 118 mg, 85%; pale yellow
solid; δH (400 MHz, CDCl3, Me4Si) 6.27 (s, 1 H), 7.19−7.22 (m, 1
H), 7.41 (t, J = 8.0 Hz, 1 H), 7.72 (t, J = 2.0 Hz, 1 H), 7.71−7.79 (m, 1
H); δC (100 MHz, CDCl3, Me4Si) 110.7, 116.0, 122.3, 130.5, 149.2,
156.6.
Data for 3-nitroaniline (3c):4j yield 112 mg, 81%; yellow solid;
δH (400 MHz, CDCl3, Me4Si) 4.06 (s, 2 H), 6.98 (d, J = 8.0 Hz, 1 H),
7.30 (t, J = 8.4 Hz, 1 H), 7.51 (d, J = 3.6 Hz, 1 H), 7.59 (d, J = 8.0 Hz,
1 H); δC (100 MHz, CDCl3, Me4Si) 109.0, 113.1, 120.7, 129.9, 147.5,
149.4.
Data for 4-hydroxybenzaldehyde (2d):4g yield 101 mg, 83%;
pale yellow solid; δH (400 MHz, CDCl3, Me4Si) 7.00 (d, J = 7.2 Hz, 2
H), 7.17 (s, 1 H), 7.82 (d, J = 8.4 Hz, 2 H), 9.83 (s, 1 H); δC (100
MHz, CDCl3, Me4Si) 116.3, 129.7, 132.8, 162.3, 191.7.
Data for 4-aminobenzaldehyde (3d):4f yield 85 mg, 70%;
yellow solid; δH (400 MHz, CD3COCD3, Me4Si) 7.00−7.04 (m, 2 H),
7.81 (d, J = 9.6 Hz, 2 H), 9.85 (s, 1 H); δC (100 MHz, CD3COCD3,
Me4Si) 117.9, 118.5, 134.2, 136.2, 192.8.
Data for 4-chlorophenol (2e):3g yield 105 mg, 82%; white solid;
δH (400 MHz, CDCl3, Me4Si) 5.40 (s, 1 H), 6.78 (d, J = 8.8 Hz, 2 H),
7.20 (d, J = 8.8 Hz, 2 H); δC (100 MHz, CDCl3, Me4Si) 116.8, 125.9,
129.7, 154.0.
Data for 4-chloroaniline (3e):4h yield 102 mg, 80%; white solid;
δH (400 MHz, CDCl3, Me4Si) 3.39 (s, 2 H), 6.77 (m, 2 H), 7.19 (m, 2
H); δC (100 MHz, CDCl3, Me4Si) 116.4, 123.4, 129.3, 145.0.
Data for 4-methoxyaniline (3f):4h yield 104 mg, 85%; colorless
oil; δH (400 MHz, CDCl3, Me4Si) 3.44 (s, 2 H), 3.75 (s, 3 H), 6.65−
6.77 (m, 4 H); δC (100 MHz, CDCl3, Me4Si) 55.8, 114.9, 116.6, 139.9,
152.9.
Data for 4-methoxyphenol (2f):3g yield 105 mg, 85%; colorless
solid; δH (400 MHz, CDCl3, Me4Si) 3.77 (s, 3 H), 6.76−6.81 (m, 4
H); δC (100 MHz, CDCl3, Me4Si) 56.0, 115.0, 116.2, 149.7, 153.8.
Data for 2,6-dimethylphenol (2g):4g yield 86 mg, 70%; white
solid; δH (400 MHz, CDCl3, Me4Si) 2.27 (s, 6 H), 4.67 (s, 1 H), 6.78
(t, J = 7.2 Hz, 1 H), 7.00 (d, J = 7.6 Hz, 2 H); δC (100 MHz, CDCl3,
Me4Si) 16.0, 120.4, 123.2, 128.8, 152.3.
Data for 2,6-dimethylaniline (3g):4f yield 88 mg, 73%; yellow
oil; δH (400 MHz, CDCl3, Me4Si) 2.25 (s, 6 H), 3.57 (s, 2 H), 6.72 (t,
J = 8.0 Hz, 1 H), 7.02 (d, J = 8.0 Hz, 2 H); δC (100 MHz, CDCl3,
Me4Si) 17.6, 118.0, 121.6, 128.2, 142.7.
Data for 4-tert-butylaniline (3h): yield 109 mg, 73%; red solid;
δH (400 MHz, CDCl3, Me4Si) 1.29 (s, 9 H), 6.66 (d, J = 8.0 Hz, 2 H),
7.20 (d, J = 8.0 Hz, 2 H); δC (100 MHz, CDCl3, Me4Si) 31.7, 34.0,
115.1, 126.2, 141.6, 143.9.
Data for 4-tert-butylphenol (2h): yield 108 mg, 72%; colorless
solid; δH (400 MHz, CDCl3, Me4Si) 1.30 (s, 9 H), 6.77 (d, J = 7.2 Hz,
2 H), 7.26 (d, J = 6.8 Hz, 2 H); δC (100 MHz, CDCl3, Me4Si) 31.7,
34.2, 114.9, 126.5, 143.6, 153.3.
Data for 4-(methylthio)phenol (2i):3f yield 98 mg, 70%; yellow
solid; δH (400 MHz, CDCl3, Me4Si) 2.44 (s, 3 H), 6.78−6.80 (m, 2
H), 7.22−7.24 (m, 2 H); δC (100 MHz, CDCl3, Me4Si) 18.3, 116.2,
130.6, 131.0, 154.4.
Data for 4-(methylthio)aniline (3i): yield 110 mg, 79%; colorless
oil; δH (400 MHz, CDCl3, Me4Si) 2.42 (s, 3 H), 3.52 (s, 2 H), 6.64(d,
J = 8.0 Hz, 2 H), 7.19 (d, J = 8.0 Hz, 2 H); δC (100 MHz, CDCl3,
Me4Si) 18.9, 115.9,126.0, 131.2, 145.2.
Data for naphthalen-1-ol (2j):3g yield 110 mg, 77%; colorless
solid; δH (400 MHz, CDCl3, Me4Si) 5.51 (s, 1 H), 6.83 (d, J = 7.6 Hz,
1 H), 7.35 (t, J = 8.0 Hz, 1 H), 7.49−7.57 (m, 3 H), 7.86−7.89 (m, 1
H), 8.23−8.25 (m, 1 H); δC (100 MHz, CDCl3, Me4Si) 108.7, 120.7,
121.5, 124.3, 125.3, 125.8, 126.4, 127.7, 134.7, 151.3.
Data for naphthalen-1-amine (3j):4j yield 100 mg, 70%; white
soild; δH (400 MHz, CDCl3, Me4Si) 4.16 (s, 2 H), 6.80 (d, J = 6.8 Hz,
1 H), 7.29−7.36 (m, 2 H), 7.47−7.48 (m, 2 H), 7.83−7.84 (m, 2 H);
δC (100 MHz, CDCl3, Me4Si) 109.8, 119.1, 120.9, 123.8, 125.0, 126.0,
126.5, 128.7, 134.6, 142.2.
Data for cyclohexanol (2k): yield 35 mg, 35%; colorless oil; δH
(400 MHz, CDCl3, Me4Si) 1.11−1.29 (m, 5 H), 1.49−1.52 (m, 1 H),
1.69−1.71 (m, 2 H), 1.84−1.85 (m, 2 H), 2.21 (s, 1 H), 3.53−3.59
(m, 1 H); δC (100 MHz, CDCl3, Me4Si) 24.2, 25.5, 35.6, 70.3.
Data for aniline (3a):4f yield 80 mg, 86%; colorless oil; δH (400
MHz, CDCl3, Me4Si) 3.46 (s, 2 H), 6.66 (d, J = 8.4 Hz, 2 H), 6.76 (t, J
= 7.6 Hz, 1 H), 7.16 (t, J = 8.0 Hz, 2 H); δC (100 MHz, CDCl3,
Me4Si) 115.1, 118.5, 129.3, 146.4.
ASSOCIATED CONTENT
■
S
* Supporting Information
Diagram of the experimental device and NMR spectra of the
products. This material is available free of charge via the
Data for 4-aminobenzonitrile (3b):4h yield 97 mg, 82%; yellow
solid; δH (400 MHz, CDCl3, Me4Si) 4.22 (s, 2 H), 6.65 (d, J = 7.2 Hz,
E
dx.doi.org/10.1021/jo400981f | J. Org. Chem. XXXX, XXX, XXX−XXX