V. Vajpayee et al. / Tetrahedron 69 (2013) 3511e3517
3515
sample was quantified from band intensities using Bio-Rad Quan-
tity One, version 2000 software. Similarly, supercoiled pUC19 DNA
(5 mg) with 0.3 mM of 2a with different time intervals was allowed
to incubate and followed by agarose gel electrophoresis as de-
scribed above.
d
9.19 (s, 1H), 8.12 (s, 1H), 7.69 (d, J¼7.8 Hz, 1H), 7.51 (d, J¼7.8 Hz,
1H), 3.29 (d, J¼14.7 Hz, 1H), 2.75 (d, J¼14.7 Hz, 1H), 2.65e2.30 (m,
2H), 2.05 (m, 2H), 1.89 (d, J¼18.3 Hz, 1H), 1.65e1.36 (m, 2H), 1.12
13
3
(s, 3H), 0.85 (s, 3H); C NMR (CD OD, 75 MHz) d 218.3, 142.9,
137.8, 136.7, 136.3, 134.5, 134.3, 130.6, 59.7, 48.6, 48.3, 44.2, 43.8,
2
ꢂ1
7.9, 25.9, 20.6, 20.2; IR (cm ) 3702, 2925, 1730, 1574, 1436,
3
.3. Synthesis of arenediazonium camphorsulfonates 2
1206, 950, 760.
Sodium nitrite (1.1 mmol) was added at room temperature to
3.3.6. 4-Bromobenzenediazonium camphorsulfonate (2f). Yellow
a solution of camphorsulfonic acid (1.1 mmol) in AcOH (8 ml) and
stirred for 5 min. The corresponding aniline (1.0 mmol) was
added and the mixture was stirred for 5e20 min until TLC in-
dicated the complete consumption of the aniline. The ether was
poured into reaction solution to yield pure product. The resulting
solid was filtered, washed by ether (20e40 ml), and dried under
vacuum.
Caution! In our two laboratories there was no case of sudden
decomposition during the preparation, purification, and handling
of salts 2ae2j. Nevertheless it must be kept in mind that in general
diazonium salts in the dry state are potentially explosive. Therefore
they must be carefully stored and handled.
solid. Anal. Calcd for C16
Found: C, 45.97; H, 4.29; N, 6.47. H NMR (CD
H
19BrN
2
O
4
S: C, 46.27; H, 4.61; N, 6.75.
OD, 300 MHz) 8.55
1
3
d
(d, J¼9.0 Hz, 2H), 8.23 (d, J¼9.0 Hz, 2H), 3.29 (d, J¼14.7 Hz, 1H), 2.75
(d, J¼14.7 Hz, 1H), 2.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d,
13
J¼18.3 Hz, 1H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR
(CD
3
OD, 75 MHz)
d
216.9, 137.7, 134.9, 133.7, 114.4, 58.2, 47.1, 46.8,
ꢂ1
42.6, 42.3, 26.4, 24.3, 19.0, 18.8; IR (cm ) 3473, 3120, 2958, 2620,
1744, 1555, 1529, 1156, 1044, 816, 616, 522.
3.3.7. 2-Bromobenzenediazonium camphorsulfonate (2g). Yellow
solid. Anal. Calcd for C16
Found: C, 45.99; H, 4.30; N, 6.39. H NMR (CD
H19BrN
2
O
4
S: C, 46.27; H, 4.61; N, 6.75.
OD, 300 MHz) 8.78
1
3
d
(
d, J¼8.4 Hz,1H), 8.28 (d, J¼8.1 Hz,1H), 8.20 (t, J¼8.0 Hz,1H), 7.99 (t,
3
.3.1. 4-Nitrobenzenediazonium camphorsulfonate (2a). Cream yel-
low solid. Anal. Calcd for C16 S: C, 50.39; H, 5.02; N, 11.02.
Found: C, 50.16; H, 5.25; N, 11.31. H NMR (300 MHz, CD OD) 8.95
d, J¼9.6 Hz, 2H), 8.74 (d, J¼9.0 Hz, 2H), 3.29 (d, J¼14.7 Hz, 1H), 2.75
d, J¼14.7 Hz, 1H), 2.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d,
J¼8.0 Hz, 1H), 3.29 (d, J¼14.7 Hz, 1H), 2.75 (d, J¼14.7 Hz, 1H),
H
19
N
3
O
6
2.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d, J¼18.3 Hz, 1H), 1.65e1.36
1
13
3
d
(m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR (CD
3
OD, 75 MHz)
d
218.3,
(
(
143.6, 137.1, 136.6, 131.9, 126.2, 120.4, 59.6, 49.6, 48.3, 44.2, 43.7,
ꢂ1
27.9, 25.9, 20.5, 20.2; IR (cm ) 3809, 3699, 2962, 1741, 1462, 1207,
13
J¼18.3 Hz, 1H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR
1039, 766, 607.
(
CD
3
OD, 75 MHz)
d
218.4, 156.2, 135.9, 127.5, 122.4, 59.7, 48.6, 48.3,
ꢂ1
4
4.2, 43.8, 27.9, 25.8, 20.6, 20.3; IR (cm ) 3471, 3270, 3106, 2959,
3.3.8. 4-Chlorobenzenediazonium camphorsulfonate (2h). Brownish
1741, 1599, 1521, 1347, 1240, 1172, 1040, 855, 749, 691, 518.
yellow solid. Anal. Calcd for C16
H
19ClN
2
O
4
S: C, 51.82; H, 5.16; N,
OD)
1
7.55. Found: C, 51.64; H, 5.37; N, 7.33. H NMR (300 MHz, CD
3
3
.3.2. 3-Nitrobenzenediazonium camphorsulfonate (2b). Pale yel-
low solid. Anal. Calcd for C16 S: C, 50.39; H, 5.02; N, 11.02.
Found: C, 50.04; H, 5.19; N, 10.94. H NMR (300 MHz, CD OD) 9.6
s, 1H), 9.06 (d, J¼8.4 Hz, 2H), 8.26 (t, J¼8.4 Hz, 1H), 3.29 (d,
d
7.56 (m, 2H), 7.42 (m, 2H), 3.29 (d, J¼14.7 Hz, 1H), 2.75 (d,
H
19
N
3
O
6
J¼14.7 Hz, 1H), 2.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d, J¼18.3 Hz,
1
13
3
d
1H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR (CD
3
OD,
(
75 MHz) 216.9, 138.1, 135.4, 132.9, 114.7, 59.6, 49.5, 48.2, 44.1, 43.7,
27.9, 25.9, 20.5, 20.2; IR (cm ) 3460, 2954, 2605, 2359, 1741, 1626,
1480, 1168, 1041, 809, 610.
d
ꢂ1
J¼14.7 Hz, 1H), 2.75 (d, J¼14.7 Hz, 1H), 2.65e2.30 (m, 2H), 2.05 (m,
2
3
H), 1.89 (d, J¼18.3 Hz, 1H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s,
13
H); C NMR (CD
3
OD, 75 MHz) d 218.4, 148.5, 138.9, 136.5, 134.4,
1
29.5, 118.7, 59.7, 48.6, 48.3, 44.1, 43.8, 27.9, 25.9, 20.5, 20.2; IR
3.3.9. 4-Iodobenzenediazonium camphorsulfonate (2i). Dark blue
ꢂ1
(
cm ) 3448, 3094, 2962, 1740, 1537, 1355, 1177, 1049, 670, 535.
solid. Anal. Calcd for C16
H
19IN
2
O
4
S: C, 41.57; H, 4.14; N, 6.06. Found:
OD) 7.92 (d,
1
C, 41.71; H, 4.32; N, 5.87. H NMR (300 MHz, CD
3
d
3
.3.3. 2-Nitrobenzenediazonium camphorsulfonate (2c). Cream yel-
low solid, Anal. Calcd for C16 S: C, 50.39; H, 5.02; N, 11.02.
Found: C, 50.45; H, 4.87; N, 11.27. H NMR (300 MHz, CD OD) 9.13
d, J¼8.1 Hz,1H), 8.87 (d, J¼8.4 Hz, 1H), 8.59 (t, J¼7.5 Hz,1H), 8.42 (t,
J¼7.8 Hz, 1H), 3.29 (d, J¼14.7 Hz, 1H), 2.75 (d, J¼14.7 Hz, 1H),
.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d, J¼18.3 Hz, 1H), 1.65e1.36
J¼7.8 Hz, 2H), 7.20 (d, J¼8.4 Hz, 2H), 3.29 (d, J¼14.7 Hz, 1H), 2.75 (d,
H
19
N
3
O
6
J¼14.7 Hz, 1H), 2.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d, J¼18.3 Hz,
1
13
3
d
1H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR (CD
3
OD,
(
75 MHz) d 218.4, 140.7, 132.1, 126.4, 95.1, 59.7, 47.1, 46.8, 44.2, 43.7,
ꢂ1
27.9, 25.9, 20.6, 20.3; IR (cm ) 3460, 2954, 2605, 2360, 1740, 1626,
1450, 1168, 1041, 808, 610.
2
13
(
m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR (CD
3
OD, 75 MHz) d 218.4,
1
46.4, 143.3, 138.1, 137.8, 129.5, 113.8, 59.7, 48.6, 48.3, 44.1, 43.8,
3.3.10. 4-Methoxybenzenediazonium camphorsulfonate (2j). White
ꢂ1
27.9, 25.9, 20.5, 20.2; IR (cm ) 3456, 3087, 2959, 1738, 1550, 1455,
solid. Anal. Calcd for C17
H
22
N
2
O
5
S: C, 55.72; H, 6.05; N, 7.64. Found:
OD) 7.32 (d,
1
1191, 1042, 791, 601, 524.
C, 55.51; H, 6.23; N, 7.44. H NMR (300 MHz, CD
3
d
J¼6.9 Hz, 2H), 7.07 (d, J¼6.6 Hz, 2H), 3.85 (s, 3H), 3.29 (d, J¼14.7 Hz,
3
.3.4. 4-Benzonitrilediazonium camphorsulfonate (2d). Yellow solid.
1H), 2.75 (d, J¼14.7 Hz,1H), 2.65e2.30 (m, 2H), 2.05 (m, 2H),1.89 (d,
13
Anal. Calcd for C17
5
H
19
N
3
O
4
1
S: C, 56.50; H, 5.30; N, 11.63. Found: C,
OD) 8.82 (d,
J¼18.3 Hz, 1H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR
6.74; H, 5.08; N, 11.45. H NMR (300 MHz, CD
3
d
(CD
3
OD, 75 MHz)
d
218.4, 161.6, 125.4, 124.4, 116.4, 59.7, 56.3, 49.6,
ꢂ1
J¼8.7 Hz, 2H), 8.37 (d, J¼8.7 Hz, 2H), 3.29 (d, J¼14.7 Hz, 1H), 2.75 (d,
48.3, 44.2, 43.8, 27.9, 25.8, 20.6, 20.3; IR (cm ) 2957, 2636, 2064,
1741, 1624, 1514, 1185, 1043, 825, 606, 513.
J¼14.7 Hz, 1H), 2.65e2.30 (m, 2H), 2.05 (m, 2H), 1.89 (d, J¼18.3 Hz,
13
1
7
4
3
H), 1.65e1.36 (m, 2H), 1.12 (s, 3H), 0.85 (s, 3H); C NMR (CD OD,
5 MHz)
d
216.8, 134.8, 133.9, 123.8, 117.3, 112.0 58.2, 47.1, 46.8, 42.6,
3.4. Typical procedure for the subsequent bromination of
arenediazonium camphorsulphonate salt 2d
ꢂ1
2.3, 26.4, 24.4, 18.9, 18.7; IR (cm ) 3431, 3090, 2964, 2604, 2340,
1725, 1411, 1172, 1035, 855, 532.
3.4.1. 4-Bromobenzonitrile. Potassium bromide (0.52 g, 2.5 mmol)
3
.3.5. 2-Benzonitrilediazonium camphorsulfonate (2e). Ivory brown
solid. Anal. Calcd for C17 S: C, 56.50; H, 5.30; N, 11.63.
Found: C, 56.27; H, 5.02; N, 11.39. H NMR (300 MHz, CDCl
was added at room temperature to a solution of 2d (0.36 g,
1.0 mmol) in water (10 ml), and the mixture was stirred for 60 min
until a negative diazonium test with 2-naphthol. Pure 4-
H
19
N
3
O
4
1
3
)