Benzo[b]phosphole-Containing p-Electron Systems
10.7 Hz, CH), 128.33 (d, JCP =8.2 Hz, CH), 128.82 (d, JCP =12.3 Hz, CH),
128.82 (d, JCP =101.3 Hz, C), 129.71 (d, JCP =10.7 Hz, CH), 129.94 (d,
>3008C; 1H NMR (400 MHz, CDCl3): d=7.32–7.39 (m, 6H), 7.42–7.47
(m, 4H), 7.54–7.58 (m, 2H), 7.68–7.76 (m, 8H), 7.99 ppm (dd, J=10 Hz,
J=3.6 Hz, 2H); 31P{1H} NMR (162 MHz, CDCl3): d=33.85 ppm; HRMS
(FAB): m/z (%) calcd for C34H2279Br2O2P2: 682.9540 [M+H+]; found:
682.9542 [M+H+]; trans-8: Rf =0.37 (15:1, CHCl3/EtOAc); m.p.:
>3008C; 1H NMR (400 MHz, CDCl3): d=7.34–7.39 (m, 6H), 7.43–7.48
(m, 4H), 7.55–7.59 (m, 2H), 7.66–7.72 (m, 8H), 7.99 ppm (dd, J=10 Hz,
J=3.6 Hz, 2H); 31P{1H} NMR (162 MHz, CDCl3): d=34.45 ppm; HRMS
(FAB): m/z calcd for C34H2279Br2O2P2: 682.9540 [M+H+]; found:
682.9542.
J
CP =4.9 Hz, CH), 130.61 (d, JCP =35.4 Hz, C), 130.76 (d, JCP =105.2 Hz,
C), 130.78 (d, JCP =10.7 Hz, CH), 132.39 (d, JCP =3.3 Hz, CH), 133.29 (d,
J
CP =1.6 Hz, CH), 135.82 (d, JCP =87.3 Hz, C), 141.74 (d, JCP =22.2 Hz,
C), 159.94 ppm (s, C); 31P{1H} NMR (162 MHz, CDCl3): d=35.32 ppm;
HRMS (FAB): m/z calcd for C21H1679BrO2P: 411.0150 [M+H+]; found:
411.0143.
3-Bromo-1-phenyl-2-(4-trifluoromethylphenyl)benzo[b]phosphole-P-
oxide (2d): This compound was prepared in a similar manner as de-
scribed for 2a-Br using (2-bromophenyl)(4-trifluoromethylphenyl)acety-
lene (3d) (163 mg, 0.50 mmol) as a starting material. The purification by
1,2-Diphenylbenzo[b]phosphole-P-oxide (2a-H): To a suspension of 2a-
Br (100 mg, 0.26 mmol) in anhydrous toluene (2.0 mL) was added HSiCl3
(0.11 mL, 1.1 mmol) in one portion. After stirring for 1 h, all volatile
compounds were removed under reduced pressure. Toluene (2 mL) was
added and the resulting suspension was filtered through a plug of Celiteꢂ
under an argon atmosphere and rinsed with toluene (4 mL). After con-
centration of the filtrate, the resulting pale solids were dissolved in anhy-
drous THF (4.0 mL). To this solution was added tBuLi in pentane
(1.58m, 0.34 mL, 0.54 mmol) at À788C and stirred for 1 h. The reaction
mixture was quenched with H2O (0.5 mL) and allowed to warm to room
temperature. Then, the resulting mixture was oxidized with an aqueous
solution of H2O2 (0.5 mL, 30%) at 08C and stirred for 30 min at ambient
temperature. The reaction mixture was quenched with an aqueous solu-
tion of Na2SO3 (15 mL, 10%) at 08C and separated into two layers. The
aqueous layer was extracted with CH2Cl2 (100 mL), and the combined or-
ganic layer was washed with an aqueous solution of Na2SO3 (100 mL,
10%), H2O (100 mL), and brine (100 mL), and then dried over anhy-
drous Na2SO4, and filtered. After concentration of the filtrate under re-
duced pressure, the resulting solids were subjected to a silica gel column
chromatography (5:1, CHCl3/EtOAc), followed by further purification
using a reversed phase HPLC to afford 2a-H (67 mg, 0.22 mmol, 84%)
as colorless solids. Rf =0.33 (5:1, CHCl3/EtOAc); m.p. (MPA100): 152.6–
154.78C; 1H NMR (400 MHz, CDCl3): d=7.27–7.42 (m, 7H), 7.46–7.53
(m, 2H), 7.55–7.64 (m, 2H), 7.70 (d, J=7.6 Hz, 2H), 7.73–7.78 ppm (m,
2H); 31P{1H} NMR (162 MHz, CDCl3): d=39.75 ppm; HRMS (FAB):
m/z calcd for C20H15OP: 303.0939 [M+H+]; found: 303.0939.
a
silica gel column chromatography (10:1, CHCl3/EtOAc) gave 2d
(179 mg, 0.40 mmol, 80%) as colorless solids. Rf =0.39 (10:1, CHCl3/
EtOAc); m.p. (MPA100): 141.0–141.28C; 1H NMR (400 MHz, CDCl3):
d=7.37–7.42 (m, 2H), 7.47–7.52 (m, 2H), 7.59–7.70 (m, 6H), 7.75–
7.77 ppm (m, 3H); 13C{1H} NMR (100 MHz, CDCl3): d=123.87 (d, JCF
=
270.8 Hz, CF3), 125.14 (d, JCP =9.9 Hz, CH), 125.53 (dd, JCF =4.1 Hz,
CP =7.4 Hz, CH), 128.01 (d, JCP =103.0 Hz, C), 128.72 (d, JCP =9.0 Hz,
CH), 128.94 (d, JCP =20.5 Hz, CH), 129.03 (d, JCP =28.8 Hz, CH), 130.64
(d, JCP =11.5 Hz, CH), 130.65 (d, JCF =32.1 Hz, C), 130.91 (d, JCP
10.7 Hz, CH), 130.95 (d, JCP =106.2 Hz, C), 132.85 (d, JCP =2.5 Hz, CH)
133.61 (d, JCP =2.5 Hz, CH), 134.17 (d, JCP =33.0 Hz, C), 135.69 (d, JCP
J
=
=
8.2 Hz, C), 135.77 (d, JCP =87.3 Hz, C), 141.29 ppm (d, JCP =21.4 Hz, C);
31P{1H} NMR (162 MHz, CDCl3): d=35.55 ppm; 19F NMR (376 MHz,
CDCl3): d=À62.59 ppm; HRMS: m/z calcd for C20H1379BrF3OP: 448.9918
[M+H+]; found: 448.9916.
3-Bromo-2-(N,N-dimethylaminophenyl)-1-phenylbenzo[b]phosphole-P-
oxide (2e): This compound was prepared in a similar manner as de-
scribed for 2a-Br using (2-bromophenyl)(4-N,N-dimethylaminophenyl)a-
cetylene (3e) (1.21 g, 4.00 mmol) as a starting material. After the separa-
tion by a silica gel column chromatography (4:1, CHCl3/EtOAc), the re-
sulting crude product was purified using a reversed phase HPLC to
afford 2e (35 mg, 0.080 mmol, 2%) as yellow solids. Rf =0.39 (4:1,
CHCl3/EtOAc); m.p. (MPA100): 190–1918C; 1H NMR (400 MHz,
CDCl3): d=2.94 (s, 6H), 6.65 (d, J=8.8 Hz, 2H), 7.32–7.38 (m, 3H),
7.43–7.47 (m, 1H), 7.55–7.60 (m, 2H), 7.65–7.71 (m, 3H), 7.79 ppm (d,
J=8.8 Hz, 2H); 13C{1H} NMR (100 MHz, CDCl3): d=40.01 (s, CH3),
111.59 (s, CH), 119.33 (brs), 124.01 (d, JCP =10.7 Hz, CH), 127.62 (d,
3-(Hydroxydiphenylmethyl)-1,2-diphenylbenzo[b]phosphole-P-oxide (9):
To a suspension of 2a-Br (381 mg, 1.0 mmol) in anhydrous toluene
(5.0 mL) was added HSiCl3 (0.40 mL, 4.0 mmol) in one portion. After
stirring for 1 h, all volatile compounds were removed under reduced pres-
sure, and to the residue was added toluene (2 mL). The resulting suspen-
sion was filtered through a plug of Celite under an argon atmosphere
and rinsed with toluene (6 mL). After concentration of the filtrate, the
resulting pale solids were dissolved in anhydrous THF (5.0 mL). To this
solution was added tBuLi in pentane (1.58m, 1.27 mL, 2.0 mmol) over
5 min at À788C. After stirring for 1 h, benzophenone (200 mg, 1.1 mmol)
was added in one portion. The resulting mixture was allowed to warm to
room temperature and stirred for 1 h. Then, the reaction mixture was
quenched with a saturated aqueous solution of NH4Cl (1 mL) at 08C, fol-
lowed by oxidation with an aqueous solution of H2O2 (0.5 mL, 30%),
and stirred for 1 h at room temperature. After addition of an aqueous so-
lution of Na2SO3 (15 mL, 10%) and H2O (30 mL) at 08C, the resulting
yellow precipitates were filtered and washed with H2O (10 mL) and ace-
tone (10 mL) to afford 9 (179 mg, 0.37 mmol, 37%) as colorless solids.
M.p. (MPA100): 260.4–261.28C; 1H NMR (400 MHz, CDCl3): d=3.08
(br, 1H), 6.75 (br, 4H), 6.94–7.01 (m, 6H), 7.11–7.13 (m, 2H), 7.33–7.40
(m, 12H), 7.49–7.57 (m, 6H), 7.64–7.68 ppm (m, 2H); 13C{1H} NMR
(100 MHz, CDCl3): d=82.13 (d, JCP =14.0 Hz, C), 127.17 (d, JCP =2.4 Hz,
CH), 127.75 (s, CH), 127.86 (d, JCP =2.4 Hz, CH), 127.97 (d, JCP =9.9 Hz,
CH), 127.98 (s, CH), 128.13 (d, JCP =9.1 Hz, CH), 128.18 (d, JCP =9.1 Hz,
CH), 129.52 (d, JCP =3.3 Hz, C), 128.58 (d, JCP =12.4 Hz, CH), 128.77 (d,
J
CP =35.4 Hz, C), 128.16 (d, JCP =8.2 Hz, CH), 128.78 (d, JCP =13.2 Hz,
CH), 129.11 (d, JCP =10.7 Hz, CH), 129.71 (d, JCP =6.6 Hz, H), 130.73 (d,
CP =105.0 Hz, C), 132.20 (d, JCP =2.5 Hz, CH), 133.18 (d, JCP =2.4 Hz,
J
CH), 135.58 (d, JCP =87.2 Hz, C), 142.24 (d, JCP =23.0 Hz, C), 150.33 ppm
(brs, C); One doublet signal of a quarter carbon may be overlapped;
31P{1H} NMR (162 MHz, CDCl3): d=35.58 ppm; HRMS (FAB): m/z
calcd for C22H1979BrNOP: 424.0461 [M+H+]; found: 424.0466.
3-Bromo-1-phenyl-2-trimethylsilylbenzo[b]phosphole-P-oxide (6): This
compound was prepared in a similar manner as described for 2a-Br using
5 (253 mg, 1.0 mmol) as a starting material. The purification by a silica
gel column chromatography (5:1, CHCl3/EtOAc) gave
6 (217 mg,
0.58 mmol, 58%) as colorless solids. Rf =0.34 (5:1, CHCl3/EtOAc); m.p.
(DSC): 159.28C; 1H NMR (400 MHz, CDCl3): d=0.24 (s, 9H), 7.37–7.44
(m, 3H), 7.49–7.59 (m, 3H), 7.63–7.70 ppm (m, 3H); 13C{1H} NMR
(100 MHz, CDCl3): d=À1.20 (d, JCP =1.7 Hz, CH3), 124.06 (d, JCP
=
11.6 Hz, CH), 127.90 (d, JCP =9.1 Hz, CH), 128.77 (d, JCP =12.3 Hz, CH),
130.31 (d, JCP =10.7 Hz, CH), 130.82 (d, JCP =10.7 Hz, CH), 132.16 (d,
J
CP =2.5 Hz, CH), 132.83 (d, JCP =1.7 Hz, CH), 134.41 (d, JCP =101 Hz,
C), 137.30 (d, JCP =51.1 Hz, C), 142.54 (d, JCP =27.9 Hz, C), 145.90 ppm
(d, JCP =22.3 Hz, C); One of the doublet signal of a quaternary carbon,
paired with the signal at 129.83 ppm, may be overlapped; 31P{1H} NMR
(162 MHz, CDCl3): d=35.28 ppm; HRMS (FAB): m/z calcd for
C17H1879BrOPSi: 377.0126 [M+H+]; found: 377.0125.
J
CP =9.1 Hz, CH), 131.05 (d, JCP =10.7 Hz, CH), 131.34 (d, JCP =103.8 Hz,
C), 132.16 (d, JCP =2.4 Hz, CH), 132.41 (d, JCP =1.7 Hz, CH), 138.64 (d,
CP =90.6 Hz, C), 143.50 (d, JCP =28.0 Hz, C), 144.07 (d, JCP =24.7 Hz, C),
3,7-Dibromo-1,2,5,6-tetraphenylbenzo[1,2-b:4,5-b’]diphosphole-P,P’-diox-
ide (8): This compound was prepared in a similar manner as described
for 2a-Br using 7 (6.12 g, 14 mmol) as a starting material. The purifica-
tion by a silica gel column chromatography (15:1, CHCl3/EtOAc) gave
trans-8 (3.21 g, 4.69 mmol, 34%) and cis-8 (3.20 g, 4.68 mmol, 33%) as
yellow solids. cis-8: Rf =0.09 (15:1, CHCl3/EtOAc); m.p. (MPA100):
J
152.21 ppm (d, JCP =19.8 Hz, C); One of the doublet signals of a quater-
nary carbon paired with the signal at 129.95 ppm and one singlet signal
of a CH carbon may be overlapped; 31P{1H} NMR (162 MHz, CDCl3):
d=39.09 ppm; HRMS (FAB): m/z calcd for C33H25O2P: 485.1670
[M+H+]; found: 485.1670.
Chem. Asian J. 2009, 4, 1729 – 1740
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1737