Unsaturated Phosphine Boranes
lytical TLC on K6F silica gel 60A, 9:1 DCM/MeOH, Rf ) 0.45:
HRMS for C22H23O2P; M + 1, m/z 351.1522, error ) 2 ppm,
base peak ) 351 amu; IR (neat, cm-1) 3304, O-H; 1173, Pd
O; 400 MHz NMR (CDCl3, ppm) δ 7.77-7.68 (4H, m), 7.56-
7.42 (6H, m), 7.37-7.20 (5H, m), 4.73-4.66 (1H, m), 2.45 (1H,
d, J ) 3.7 Hz), 2.41-2.27 (2H, m), 1.97-1.68 (4H, m); 13C NMR
(100 MHz, CDCl3, ppm) δ 131.7, 130.8, 130.8 (d, J C-P ) 19.1
Hz), 128.6 (d, J C-P ) 13.0 Hz), 128.5, 127.5, 125.7, 73.8, 39.8
diphenylmethylphosphine-borane complex18 (143.9 mg, 0.672
mmol) in THF (5 mL), and a pale yellow color developed. After
the mixture was stirred at -78 °C for 2 h, prenyl bromide (97
µL, 0.840 mmol) was added. After 14 h at room temperature,
the reaction was quenched with water and extracted with
EtOAc. The extracts were washed with brine and dried (Na2-
SO4). After removal of solvent (aspirator), the residue was
purified by flash chromatography on EM silica gel 60 (14 × 2
cm) with 24:1 hexane/acetone as the eluent to give 138 mg
(73%) of the desired compound as a colorless liquid; analytical
TLC on K6F silica gel 60A, 19:1 hexane/acetone, Rf ) 0.34:
HRMS for C18H2411BP; M - 1, m/z 281.1621, error ) 3 ppm,
base peak ) 269 amu; IR (neat, cm-1) 2382, B-H; 1436, Cd
C; 400 MHz NMR (CDCl3, ppm) δ 7.71-7.64 (4H, m), 7.51-
7.40 (6H, m), 5.12-5.06 (1H, m), 2.27-2.13 (4H, m), 1.62 (3H,
s), 1.51 (3H, s), 1.50-0.50 (3H, m); 13C NMR (100 MHz, CDCl3,
ppm) δ 133.1, 132.1 (d, J C-P ) 9.2 Hz), 131.1 (d, J C-P ) 3.0
Hz), 129.5 (d, J C-P ) 54.9 Hz), 128.7 (d, J C-P ) 10.0 Hz), 123.2
(d, J C-P ) 15.3 Hz), 25.9 (d, J C-P ) 35.8 Hz), 25.6, 21.7, 17.6;
31P NMR (162 MHz, CDCl3, ppm) δ 15.4 (m); 11B NMR (115.5
MHz, CDCl3, ppm) δ -39.9 (m, W1/2 ) 250 Hz).
(d, J C-P ) 13.0 Hz), 29.2 (d, J C-P ) 71.7 Hz), 18.2 (d, J C-P
)
3.8 Hz); 31P NMR (162 MHz, CDCl3, ppm) δ 32.8.
(3-Meth yl-3-bu ten yl)d ip h en ylp h osp h in e‚BH3 (29). A
solution of s-butyllithium (1.3 M in pentane, 0.88 mL, 1.140
mmol) was added dropwise at -78 °C to a solution of
diphenylmethylphosphine-borane complex18 (195.4 mg, 0.913
mmol) in THF (5 mL) and a pale yellow color developed. After
stirring at -78 °C for 2 h, methallyl bromide (115 µL, 1.140
mmol) was added. After warming to room temperature for 2
h, the reaction was quenched with water and extracted with
EtOAc. The extracts were washed with brine and dried (Na2-
SO4). After removal of solvent (aspirator), the residue was
purified by flash chromatography on EM silica gel 60 (3 × 14
cm) with 95:5 hexane/acetone as the eluent to provide 196 mg
(80%) of the desired compound as a colorless liquid; analytical
TLC on K6F silica gel 60A, 19:1 hexane/acetone, Rf ) 0.25.
Pure material was obtained by crystallization from acetone,
mp 49-51 °C: HRMS for C17H2211BP; M - 1, m/z 267.1475,
error ) 0 ppm, base peak ) 253 amu; IR (neat, cm-1) 2382,
B-H; 2343, B-H; 1652, CdC; 400 MHz NMR (CDCl3, ppm) δ
7.72-7.65 (4H, m), 7.53-7.42 (6H, m), 4.74 (1H, s), 4.71 (1H,
s), 2.39-2.30 (2H, m), 2.22-2.14 (2H, m), 1.71 (3H, s), 1.50-
0.50 (3H, m); 13C NMR (100 MHz, CDCl3, ppm) δ 144.8 (d,
J C-P ) 13.7 Hz), 132.1 (d, J C-P ) 9.2 Hz), 131.2 (d, J C-P ) 3.1
Hz), 129.3 (d, J C-P ) 54.9 Hz), 128.8 (d, J C-P ) 10.7 Hz), 110.2,
30.6, 24.0 (d, J C-P ) 37.4 Hz), 22.4; 31P NMR (162 MHz, CDCl3,
ppm) δ 16.1 (m); 11B NMR (115.5 MHz, CDCl3, ppm) δ -39.9
(m, W1/2 ) 250 Hz).
(5-Diph en ylph osph in oyl)-2-m eth yl-3-pen tan ol (33) an d
Dip h en yl(4-m eth ylp en ta n yl)-p h osp h in e Oxid e (34). Use
of the general procedure above with (4-methyl-3-pentenyl)-
diphenylphosphine-borane complex 32 (14.7 mg, 52.1 µmol)
1
gave 13.0 mg (83%) of crude product as a colorless liquid. H
and 31P NMR analysis indicated a 53:47 mixture of 34:33. After
removal of solvent (aspirator), the residue was purified by PLC
on silica 60A (20 × 20 × 0.1 cm) with 95:5 DCM/MeOH as the
eluent. The less polar zone provided diphenyl(4-methylpenta-
nyl)phosphine oxide 34 (7.4 mg, 47%) as a colorless solid;
analytical TLC on K6F silica gel 60A, 9:1 DCM/MeOH, Rf )
0.53: HRMS for C18H23OP; M + 1, m/z 287.1576, error ) 4
ppm, base peak ) 287 amu; IR (neat, cm-1) 1181, PdO; 400
MHz NMR (CDCl3, ppm) δ 7.78-7.70 (4H, m), 7.55-7.44 (6H,
m), 2.28-2.19 (2H, m), 1.68-1.46 (3H, m), 1.32-1.24 (2H, m),
0.82 (6H, d, J ) 6.6 Hz); 13C NMR (100 MHz, CDCl3, ppm) δ
133.2 (d, J C-P ) 97.7 Hz), 131.6 (d, J C-P ) 3.1 Hz), 130.7 (d,
J C-P ) 9.2 Hz), 128.6 (d, J C-P ) 11.4 Hz), 40.3 (d, J C-P ) 14.5
Hz), 29.9 (d, J C-P ) 71.7 Hz), 27.6, 22.4, 19.3 (d, J C-P ) 3.8
Hz); 31P NMR (162 MHz, CDCl3, ppm) δ 32.5. The more polar
zone provided (5-diphenylphosphinoyl)-2-methyl-3-pentanol 33
(5.6 mg, 36%) as a colorless gum. Pure material was obtained
by crystallization from chloroform, mp 117.5-118.5 °C fine
powder: HRMS for C18H23O2P; M + 1, m/z 303.1519, error )
2 ppm, base peak ) 303 amu; IR (neat, cm-1) 3350, O-H; 1173,
PdO; 400 MHz NMR (CDCl3, ppm) δ 7.79-7.72 (4H, m), 7.56-
7.44 (6H, m), 3.44-3.36 (1H, m), 3.06 (1H, d, J ) 5.1 Hz),
2.55-2.32 (2H, m), 1.95-1.82 (1H, m), 1.73-1.58 (2H, m), 0.90
(3H, d, J ) 6.6 Hz), 0.86 (3H, d, J ) 7.0 Hz); 13C NMR (100
MHz, CDCl3, ppm) δ 132.6 (d, J C-P ) 79.3 Hz), 131.8 (m), 130.8
(4-Dip h en ylp h osp h in oyl)-2-m eth yl-1-bu ta n ol (30) a n d
Dip h en yl(3-m eth ylbu tyl)p h osp h in e Oxid e (31). Use of the
general procedure above with (3-methyl-3-butenyl)diphen-
ylphosphine-borane 29 (16.7 mg, 62.3 µmol) gave 14.6 mg
1
(81%) of crude product as a colorless liquid. H and 31P NMR
analysis indicated a 69:31 mixture of 31:30. After removal of
solvent (aspirator), the residue was purified by PLC on silica
60A (20 × 20 × 0.1 cm) with 95:5 DCM/MeOH as the eluent.
The less polar zone was collected to give diphenyl(3-methylbu-
tanyl)phosphine oxide (31, 10.0 mg, 56%) as a colorless solid;
analytical TLC on K6F silica gel 60A, 9:1 DCM/MeOH, Rf )
0.53. Pure material was obtained by crystallization from
chloroform, mp 97.5-99 °C plates: HRMS for C17H21OP; M +
1, m/z 273.1411, error ) 1 ppm, base peak ) 216 amu; IR (neat,
cm-1) 1177, PdO; 400 MHz NMR (CDCl3, ppm) δ 7.78-7.70
(4H, m), 7.55-7.44 (6H, m), 2.30-2.20 (2H, m), 1.68-1.46 (3H,
m), 0.89 (6H, d, J ) 6.6 Hz); 13C NMR (100 MHz, CDCl3, ppm)
δ 133.1 (d, J C-P ) 97.7 Hz), 131.6 (d, J C-P) 3.1 Hz), 130.8 (d,
J C-P ) 9.2 Hz), 128.6 (d, J C-P ) 10.7 Hz), 29.9 (d, J C-P ) 3.8
Hz), 29.1 (d, J C-P ) 14.5 Hz), 27.6 (d, J C-P ) 72.5 Hz), 22.0;
31P NMR (162 MHz, CDCl3, ppm) δ 34.0. The more polar zone
gave (4-diphenylphosphinoyl)-2-methyl-1-butanol (30) 3.9 mg
(22%) as a colorless oil; analytical TLC on K6F silica gel 60A,
9:1 DCM/MeOH, Rf ) 0.42: HRMS for C17H21O2P; M + 1, m/z
(d, J C-P ) 9.2 Hz), 128.7 (d, J C-P ) 1.5 Hz), 128.6 (d, J C-P
)
1.5 Hz), 76.5 (d, J C-P ) 9.2 Hz), 33.7, 26.7 (d, J C-P ) 71.7 Hz),
26.5 (d, J C-P ) 3.8 Hz), 18.7, 17.8; 31P NMR (162 MHz, CDCl3,
ppm) δ 34.5.
1,1-Dih yd r id o-2,2-d ip h en yl-5-m eth yl-1,2-bor a p h osp h i-
n a n e (37). A solution of B(C6F5)3 (9.0 mg, 0.018 mmol) in
benzene (0.25 mL) was added to a solution of (3-methyl-3-
butenyl)diphenylphosphine‚BH3 (35) (60.9 mg, 0.227 mmol) in
benzene (2 mL). After 3 h, the reaction was quenched with
triethylamine (1 mL). After removal of solvent (aspirator), the
residue was purified by PLC on Whatman silica 60A (20 × 20
× 0.1 cm) with 4:1 hexane/DCM as the eluent to give 42 mg
(69%) of cyclic phosphine borane (37) as a colorless oil;
analytical TLC on K6F silica gel 60A, 4:1 hexane/DCM, Rf )
0.59: HRMS for C17H22BP; M - 1, m/z 267.1476, error ) 1
ppm; base peak ) 267 amu; IR (neat, cm-1) 2243, B-H; 2262,
B-H; 400 MHz NMR (CDCl3, ppm) δ 7.85-7.78 (2H, m), 7.59-
7.46 (5H, m), 7.46-7.35 (3H, m), 2.62-2.50 (1H, m), 2.30-
0.80 (2H, br), 2.19-2.08 (1H, m), 1.97-1.82 (1H, m), 1.70-
1.55 (1H, br), 1.21-1.00 (2H, m), 0.91 (3H, d, J ) 6.6 Hz),
0.35-0.20 (1H, m); 13C NMR (100 MHz, CDCl3, ppm) δ 132.9
289.1356, error ) 1 ppm, base peak ) 269 amu; IR (neat, cm-1
)
3374, O-H; 1170, PdO; 400 MHz NMR (CDCl3, ppm) δ 7.78-
7.71 (4H, m), 7.56-7.44 (6H, m), 3.57-3.43 (2H, m), 2.44 (1H,
t, J ) 6.2 Hz), 2.42-2.21 (2H, m), 1.82-1.50 (3H, m), 0.91 (3H,
d, J ) 6.6 Hz); 13C NMR (100 MHz, CDCl3, ppm) δ 133.3 (d,
J C-P ) 97.7 Hz), 131.8 (d, J C-P ) 3.1 Hz), 130.8 (d, J C-P ) 8.4
Hz), 128.7 (d, J C-P ) 12.2 Hz), 66.8, 26.3 (d, J C-P ) 11.4 Hz),
26.4 (d, J C-P ) 71.7 Hz), 24.5 (d, J C-P ) 3.8 Hz), 16.4; 31P NMR
(162 MHz, CDCl3, ppm) δ 34.0.
(4-Meth yl-3-p en ten yl)d ip h en ylp h osp h in e‚BH3 (32). A
solution of s-butyllithium (1.3 M in pentane, 0.65 mL, 0.840
mmol) was added dropwise at -78 °C to a solution of
J . Org. Chem, Vol. 69, No. 12, 2004 4099