7780
J. Yoshino et al. / Tetrahedron 64 (2008) 7774–7781
4.11. Synthesis of (E)-[2-(4-fluorophenylazo)phenyl]-
dihydroxyborane ((E)-5c)
(79), 123 (58), 95 (100%). HRMS (FABþ) m/z calcd for C18H12BFN2O2
318.0976, found 318.0978. UV/vis (hexane) lmax
(
3
) 234 (1.4ꢁ104),
277 (6.5ꢁ103), 338 nm (1.6ꢁ104). Anal. Calcd for C18H12BFN2O2: C,
Boronic acid (E)-5c (445 mg, 46%) was synthesized from (E)-4-
fluoro-20-iodoazobenzene ((E)-4c) (1.30 g, 3.99 mmol). Compound
(E)-5c: yellow orange solid (benzene), mp 83.0–86.0 ꢂC (dec). 1H
67.96; H, 3.80; N, 8.81. Found: C, 67.95; H, 4.00; N, 8.85%.
4.15. Synthesis of (E)-2-{2-[4-(trifluoromethyl)phenylazo]-
phenyl}-1,3,2-benzodioxaborole ((E)-1d)
NMR (400 MHz, CDCl3)
7.57 (m, 2H), 7.82–7.86 (m, 2H), 7.87–7.90 (m, 1H), 8.08–8.12 (m,
1H). 11B NMR (128 MHz, CDCl3)
29.1 (line width h1/2¼251 Hz).
d 6.56 (br s, 2H), 7.21–7.27 (m, 2H), 7.54–
d
The reaction of boronic acid (E)-5d (98.1 mg, 0.334 mmol) and
pyrocatechol (36.7 mg, 0.333 mmol) in toluene (50 mL) for 16 h
gave (E)-1d (178.4 mg, quant.). Compound (E)-1d: brown crystals
(benzene/hexane), mp 110.0–111.0 ꢂC (dec). 1H NMR (400 MHz,
13C{1H} NMR (100 MHz, CDCl3)
d 115.53 (s, CH), 116.62 (d,
2JCF¼23.0 Hz, CH), 124.92 (d, 3JCF¼9.6 Hz, CH), 131.56 (s, CH), 131.81
4
(s, CH), 136.27 (s, CH), 148.64 (d, JCF¼3.8 Hz, CN), 156.67 (s, CN),
164.81 (d, 1JCF¼255 Hz, CF).14 19F NMR (376 MHz, CDCl3)
d
ꢀ107.36
CDCl3)
d
6.96–7.15 (m, 4H), 7.53–7.75 (m, 7H), 8.17 (d, 3J¼6.6 Hz,
to ꢀ107.26 (m). UV/vis (hexane) lmax
(3
) 236 (1.2ꢁ104), 330
1H). 11B NMR (128 MHz, CDCl3)
13C{1H} NMR (100 MHz, CDCl3)
d
d
23.6 (line width h1/2¼339 Hz).
111.81 (s, CH), 121.40 (s, CH),
(1.9ꢁ104), 440 nm (6.6ꢁ102). Anal. Calcd for C12H10BFN2O2: C,
59.06; H, 4.13; N, 11.48. Found: C, 59.16; H, 4.35; N, 11.46%.
123.31 (q, 1JCF¼272.8 Hz, CF3), 123.33 (s, CH), 126.59 (q, 3JCF¼3.3 Hz,
CH), 129.00 (s, CH), 130.76 (s, CH), 132.26 (s, CH), 133.48 (q,
2JCF¼33.2 Hz, CCF3), 134.57 (s, CH), 147.60 (s, quaternary C), 149.63
(s, quaternary C), 155.93 (s, quaternary C).14 19F NMR (376 MHz,
4.12. Synthesis of (E)-dihydroxy{2-[4-(trifluoromethyl)-
phenylazo]phenyl}borane ((E)-5d)
CDCl3)
d
ꢀ65.07 (s). MS (EI, 70 eV) m/z 368 (Mþ, 24), 195 (100), 145
Boronic acid (E)-4d (58.7 mg, 21%) was synthesized from (E)-2-
(57%). HRMS (FABþ) m/z calcd for C19H12BF3N2O2 368.0944, found
iodo-40-(trifluoromethyl)azobenzene
((E)-4d)
0.932 mmol). Compound (E)-5d: yellow orange solid (benzene), mp
184.0–187.8 ꢂC (dec). 1H NMR (400 MHz, CDCl3)
6.28 (br s, 2H),
7.56–7.62 (m, 2H), 7.80–7.84 (m, 2H), 7.86–7.94 (m, 3H), 8.11–8.14
(m, 1H). 11B NMR (128 MHz, CDCl3)
29.6 (line width h1/2¼203 Hz).
(351 mg,
368.0952. UV/vis (hexane) lmax
(3)
270 (4.8ꢁ103), 327 nm
(6.7ꢁ103). Anal. Calcd for C19H12BF3N2O2: C, 61.99; H, 3.29; N, 7.61.
d
Found: C, 62.05; H, 3.50; N, 7.56%.
d
13C{1H} NMR (100 MHz, CDCl3)
d
115.57 (s, CH), 122.82 (s, CH),
4.16. X-ray crystallographic analysis
123.65 (q, 1JCF¼272.2 Hz, CF3),126.76 (q, 3JCF¼3.8 Hz, CH),130.75 (br
2
s, CB), 131.85 (s, CH), 132.39 (s, CH), 132.92 (q, JCF¼32.6 Hz, CCF3),
X-ray diffraction data for single crystals were collected using
Rigaku MERCURY CCD. The crystal structures were solved by the
direct method and refined by full-matrix least-squares using
SHELX97.15 Crystallographic data for (E)-1a: C18H13BN2O2,
M¼300.11, monoclinic, space group P21/c, a¼5.828(3), b¼14.417(7),
136.47 (s, CH), 154.06 (s, CN), 156.55 (s, CN). 19F NMR (376 MHz,
CDCl3)
d
ꢀ64.80 (s). UV/vis (hexane) lmax
(3
) 216 (7.4ꢁ103), 327
(1.1ꢁ104), 442 nm (3.9ꢁ102). Anal. Calcd for C13H10BF3N2O2: C,
53.10; H, 3.43; N, 9.53. Found: C, 55.34; H, 3.87; N, 8.94%.
c¼17.562(9) Å,
b
¼98.9763(18)ꢂ,
U¼1457.5(13) Å3,
Z¼4,
4.13. Synthesis of (E)-2-[2-(4-methoxyphenylazo)phenyl]-
1,3,2-benzodioxaborole ((E)-1b)
Dc¼1.368 g cmꢀ3
,
m(Mo K
a
)¼0.089 mmꢀ1, 9240 reflections mea-
sured, 2518 unique, final R1 (I>2
s
(I))¼0.0347, wR2 (all
data)¼0.0952, T¼120(2) K, CCDC 687729. Crystallographic data for
The reaction of boronic acid (E)-5b (177 mg, 0.692 mmol) and
pyrocatechol (76.2 mg, 0.692 mmol) in toluene (50 mL) for 16 h
gave (E)-1b (248 mg, 98%). Compound (E)-1b: red-brown solid
(E)-1b: C19H15BN2O3, M¼330.14, monoclinic, space group P21/n,
a¼11.780(10),
b¼7.356(6),
c¼18.912(15) Å,
b
¼100.891(5)ꢂ,
U¼1609(2) Å3, Z¼4, Dc¼1.363 g cmꢀ3
,
m
(Mo K
a
)¼0.092 mmꢀ1, 9439
(benzene), mp 169.4–170.2 ꢂC. 1H NMR (400 MHz, CDCl3)
d
3.81 (s,
reflections measured, 2784 unique, final R1 (I>2
s
(I))¼0.0330, wR2
3H), 6.78–6.84 (m, 2H), 6.89–7.02 (m, 4H), 7.50–7.67 (m, 5H), 8.00–
(all data)¼0.0746, T¼120(2) K, CCDC 687730. Crystallographic data
for (E)-1c: C18H12BFN2O2, M¼318.11, monoclinic, space group P21/c,
8.05 (m, 1H). 11B NMR (128 MHz, CDCl3)
d
19.6 (line width
h1/2¼252 Hz). 13C NMR (100 MHz, CDCl3)
d
55.77 (q), 111.33 (d),
a¼6.072(2),
b¼14.239(5),
c¼17.449(6) Å,
b
¼100.206(5)ꢂ,
114.90 (d), 120.52 (d), 125.31 (d), 127.21 (d), 130.21 (d), 131.47 (d),
133.70 (d), 138.03 (s), 150.50 (s), 155.66 (s), 163.45 (s).14 MS (EI,
70 eV) m/z 300 (Mþ, 19), 195 (11), 135 (53), 107 (100), 92 (22), 77
U¼1484.7(9) Å3, Z¼4, Dc¼1.423 g cmꢀ3
,
m
(Mo K
a
)¼0.102 mmꢀ1
,
8439 reflections measured, 2550 unique, final R1 (I>2
s
(I))¼0.0382,
wR2 (all data)¼0.0999, T¼120(2) K, CCDC 687731. Crystallographic
(40%). UV/vis (hexane) lmax
(
3
) 243 (1.4ꢁ104), 277 (6.1ꢁ103),
data for (E)-5a: C12H11BN2O2, M¼226.04, monoclinic, space group
370 nm (1.8ꢁ104). Anal. Calcd for C19H15BN2O3: C, 69.12; H, 4.58; N,
P21/n, a¼14.436(7), b¼5.080(2), c¼16.529(8) Å,
b
¼112.4917(19)ꢂ,
8.49. Found: C, 68.98; H, 4.66; N, 8.31%.
U¼1119.9(9) Å3, Z¼4, Dc¼1.341 g cmꢀ3
,
m
(Mo K
a
)¼0.091 mmꢀ1
,
6620 reflections measured, 1955 unique, final R1 (I>2
s
(I))¼0.0332,
4.14. Synthesis of (E)-2-[2-(4-fluorophenylazo)phenyl]-1,3,2-
benzodioxaborole ((E)-1c)
wR2 (all data)¼0.0953, T¼120(2) K, CCDC 687732. Crystallographic
data for (E)-5b: C13H13BN2O3, M¼256.06, monoclinic, space group
P21/n, a¼11.469(6), b¼5.253(2), c¼21.151(11) Å,
b
¼103.176(3)ꢂ,
The reaction of boronic acid (E)-5c (244 mg, 1.00 mmol) and
pyrocatechol (110 mg, 1.00 mmol) in toluene (100 mL) for 16 h gave
(E)-1c (381 mg, 93%). Compound (E)-1c: brown crystals (benzene/
hexane), mp 148.4–149.8 ꢂC (dec). 1H NMR (400 MHz, CDCl3)
U¼1240.8(10) Å3, Z¼4, Dc¼1.376 g cmꢀ3
,
m
(Mo K
a
)¼0.097 mmꢀ1
,
6790 reflections measured, 2130 unique, final R1 (I>2
s
(I))¼0.0362,
wR2 (all data)¼0.0950, T¼120(2) K, CCDC 687733. Crystallographic
data for (E)-9: C14H11BN2O3, M¼266.06, monoclinic, space group
d
6.94–7.04 (m, 4H), 7.30–7.33 (m, 1H), 7.50–7.54 (m, 1H), 7.57–7.65
P21/n, a¼12.754(3), b¼12.942(3), c¼15.193(4) Å,
b
¼95.9931(11)ꢂ,
(m, 4H), 7.68–7.71 (m, 1H), 8.08–8.11 (m, 1H). 11B NMR (128 MHz,
U¼2494.0(11) Å3, Z¼8, Dc¼1.417 g cmꢀ3
,
m(Mo K
a
)¼0.100 mmꢀ1
,
CDCl3)
CDCl3)
d
21.3 (line width h1/2¼231 Hz). 13C{1H} NMR (100 MHz,
14,647
(I>2
reflections
measured, 4321 unique,
final R1
2
d
111.57 (s, CH), 116.72 (d, JCF¼23.2 Hz, CH), 121.00 (s, CH),
s
(I))¼0.0320, wR2 (all data)¼0.0880, T¼120(2) K, CCDC
125.42 (d, 3JCF¼9.1 Hz, CH), 130.51 (s, CH), 130.80 (s, CH), 131.88 (s,
CH),134.19 (s, CH),148.03 (s, quaternary C), 149.98 (s, quaternary C),
687734. Crystallographic data can be obtained, free of charge, on
application to Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: þ44 (0)1223 336033 or e-mail:
155.73 (s, quaternary C), 165.02 (d, JCF¼255 Hz, CF).14 19F NMR
1
(376 MHz, CDCl3)
d
ꢀ104.80 (s). MS (EI, 70 eV) m/z 318 (Mþ, 39),195