The Journal of Organic Chemistry
Article
CDCl3) δ 25.6 (d, JP−C = 1.7 Hz), 26.1, 26.34, 26.4, 26.5 (d, JP−C = 0.9
Hz), 31.7 (d, JP−C = 33.9 Hz), 57.9 (d, JP−C = 39.7 Hz), 125.6 (d, JP−C
= 51.2 Hz), 128.6 (d, JP−C = 9.2 Hz), 131.6 (d, JP−C = 2.9 Hz), 132.8
(d, JP−C = 7.5 Hz); 31P NMR (122 MHz, CDCl3) δ 22.44 (m). Anal.
Calcd for C13H22BOP: C, 66.13; H, 9.39. Found: C, 66.42; H, 9.42.
Hydroxymethyl(methyl)phenylphosphine−Borane (2j). According
to the general procedure, 1j (0.085 g, 0.5 mmol) was treated with BH3·
THF (1.5 mL, 1.5 mmol) and stirred at room temperature for 4 h. The
reaction afforded product 2j (0.0605 g, 99%) as an oil; Rf = 0.45
7.45 (m, 3H), 7.54−7.58 (m, 1H), 7.59−7.64 (m, 2H), 7.99−8.03 (m,
1H); 13C NMR (125 MHz, CDCl3) δ 19.1 (d, JC−P = 8.2 Hz), 55.9,
65.3 (d, JC−P = 37.2 Hz), 111.6 (d, JC−P = 4.5 Hz), 114.2 (d, JC−P
=
50.0 Hz), 122.0 (d, JC−P = 11.8 Hz), 128.1 (d, JC−P = 55.4 Hz), 128.4
(d, JC−P = 10.0 Hz), 130.8 (d, JC−P = 1.8 Hz), 132.2 (d, JC−P = 8.2 Hz),
134.0, 137.5 (d, JC−P = 12.7 Hz), 160.6; 31P NMR (202 MHz, CDCl3)
δ 27.76 (m). Anal. Calcd for C15H20BO2P: C, 65.73; H, 7.35. Found:
C, 65.45; H, 7.43.
tert-Butyl(1-hydroxyethyl)phenylphosphine−Borane (7f). Accord-
ing to the general procedure, 4f (0.114 g, 0.5 mmol) was treated with
BH3·SMe2 (142 μL, 1.5 mmol) and stirred at 60 °C for 18 h. The
reaction afforded 7f (0.083 g, 74%) as two diastereomers isolated as a
mixture (dr = 67:33). Major diastereoisomer: Rf = 0.67 (hexane/ethyl
1
(hexane/ethyl acetate = 2:1); H NMR (500 MHz, CDCl3) δ 0.35−
1.04 (bm, 3H), 1.64 (d, JH−P = 10.40 Hz, 3H), 2.08 (bs, 1H), 4.07 (s,
2H), 7.46−7.50 (m, 2H), 7.52−7.56 (m, 1H), 7.73−7.77 (m, 2H); 13C
NMR (125 MHz, CDCl3) δ 6.9 (d, JP−C = 39.1 Hz), 60.9 (d, JP−C
=
1
acetate = 2:1); H NMR (500 MHz, CDCl3) δ 0.28−0.97 (bm, 3H),
40.9 Hz), 127.0 (d, JP−C = 53.6 Hz), 128.9 (d, JP−C = 10.0 Hz), 131.8
(d, JP−C = 2.7 Hz), 131.9 (d, JP−C = 9.1 Hz); 31P NMR (202 MHz,
CDCl3) δ 11.02 (m). Anal. Calcd for C8H14BOP: C, 57.20; H, 8.40.
Found: C, 57.00; H, 8.20.
1.22 (d, JH−P = 13.56 Hz, 9H), 1.53 (dd, JH−H = 6.62 Hz, JH−P = 13.87
Hz, 3H), 2.06 (bs, 1H), 4.76 (m, 1H), 7.42−7.47 (m, 3H), 7.92−7.95
(m, 2H); 13C NMR (125 MHz, CDCl3) δ 20.6 (d, JC−P = 4.5 Hz),
26.7, 30.1 (d, JC−P = 30.0 Hz), 64.9 (d, JC−P = 37.2 Hz), 124.8 (d, JC−P
= 48.1 Hz), 128.2 (d, JC−P = 9.1 Hz), 131.3 (d, JC−P = 2.7 Hz), 134.7
(d, JC−P = 7.3 Hz); 31P NMR (202 MHz, CDCl3) δ 38.85 (m). Anal.
Calcd for C12H22BOP: C, 64.32; H, 9.90. Found:. C, 64.20; H, 9.86.
Di-c-hexyl(hydroxymethyl)phosphine−Borane (2k). According to
the general procedure, 1k (0.122 g, 0.5 mmol) was treated with BH3·
THF (1.5 mL, 1.5 mmol) and stirred at room temperature for 16 h.
The reaction afforded product 2j (0.108 g, 89%) as a solid; mp =
1
1
Minor diastereoisomer: Rf = 0.67 (hexane/ethyl acetate = 2:1); H
107.4−108.1 °C; Rf = 0.83 (hexane/ethyl acetate = 2:1); H NMR
NMR (500 MHz, CDCl3) δ 0.28−0.97 (bm, 3H), 1.19 (d, JH−P
=
(500 MHz, CDCl3 ) δ −0.12−0.62 (bm, 3H), 1.20−1.59 (m, 10H),
1.72−1.91 (m, 12H), 4.01 (s, 2H); 13C NMR (125 MHz, CDCl3) δ
13.55 Hz, 9H), 1.31 (dd, JH−H = 6.94 Hz, JH−P = 12.93 Hz, 3H), 2.06
(bs, 1H), 4.86 (m, 1H), 7.49−7.54 (m, 3H), 7.64−7.67 (m, 2H); 13C
NMR (125 MHz, CDCl3) δ 20.0 (d, JC−P = 7.3 Hz), 26.3, 29.3 (d, JC−P
= 30.0 Hz), 62.6 (d, JC−P = 40.0 Hz), 126.2 (d, JC−P = 47.2 Hz), 128.4
(d, JC−P = 47.2 Hz), 131.4 (d, JC−P = 2.7 Hz), 133.6 (d, JC−P = 6.4 Hz);
31P NMR (202 MHz, CDCl3) δ 36.48 (m). Anal. Calcd for
C12H22BOP: C, 64.32; H, 9.90. Found: C, 64.20; H, 9.86.
25.8, 26.6, 26.7, 26.8, 26.9, 29.8 (d, JP−C = 31.8 Hz), 55.5 (d, JP−C
=
37.2 Hz); 31P NMR (202 MHz, CDCl3) δ 27.51 (m). Anal. Calcd for
C13H28BOP: C, 64.48; H, 11.66. Found: C, 64.26; H, 11.59.
Di-n-hexyl(hydroxymethyl)phosphine−Borane (2l). The reaction
was performed analogously to that described above using 1l (0.11 g,
0.5 mmol), BH3·SMe2 (237 μL, 2.5 mmol) at room temperature for 4
h. The reaction afforded product 2l (0.095 g, 87%) as an oil; Rf = 0.65
(hexane/ethyl acetate = 2:1); 1H NMR (500 MHz, CDCl3) δ −0.04−
0.69 (bm, 3H), 0.87 (t, JH−H = 6.64 Hz, 6H), 1.23−1.28 (m, 8H),
1.33−1.43 (m, 4H), 1.46−1.56 (m, 4H), 1.582−1.61 (m, 4H), 2.20
(bs, 1H), 3.93 (bs, 2H); 13C NMR (125 MHz, CDCl3) δ 14.0, 20.8 (d,
JP−C = 33.6 Hz), 22.4, 22.5, 30.8 (d, JP−C = 12.7 Hz), 31.2, 57.3 (d,
JP−C = 39.1 Hz); 31P NMR (202 MHz, CDCl3) δ 18.36 (m). Anal.
Calcd for C13H32BOP: C, 63.43; H, 13.10. Found: C, 63.03; H, 13.25.
Attempted Reduction of tert-Butylmethylphenylphosphine Oxide
(3f). According to the general procedure, 3f (0.098g, 0.5 mmol) was
treated with BH3·SMe2 (0.142 mL, 1.5 mmol) and heated to reflux for
24 h. The analysis by NMR showed presence only of starting material.
The starting material 3f was recovered as a solid; 1H NMR (500 MHz,
CDCl3) δ 1.14 (d, JP−H = 15.13 Hz, 9H), 1.76 (d, JP−H = 11.98 Hz,
3H), 7.47−7.50 (m, 2H), 7.50−7.55 (m, 1H), 7.69−7.75 (m, 2H); 13C
NMR (75 MHz) δ 10.3 (d, JP−C = 65.5 Hz), 12.2, 32.5 (d, JP−C = 70.9
Hz), 128.1 (d, JP−C = 11.0 Hz), 131.38, 131.4 (d, JP−C = 8.1 Hz); 31P
NMR (202 MHz, CDCl3) δ 49.98 ppm (s). Anal. Calcd for
C11H17OP: C, 67.33; H, 8.73. Found: C, 67.45; H, 8.43.
(1-Hydroxyethyl)(methyl)phenylphosphine−Borane (7j). Accord-
ing to the general procedure, 4j (0.092 g, 0.5 mmol) was treated with
BH3·THF (1.5 mL, 1.5 mmol) and stirred at 60 °C for 24 h. The
reaction afforded product 7j (0.0655 g, 72%) as two diastereomers
isolated as a mixture (dr = 50:50). Rf = 0.51 (hexane/ethyl acetate =
1
2:1); H NMR (500 MHz, CDCl3) δ 0.35−1.01 (bm, 6H), 1.31 (dd,
JH−H = 6.94 Hz, JH−P = 14.19 Hz, 3H) and 1.33 (dd, JH−H = 6.94 Hz,
JH−P = 14.50 Hz, 3H), 1.62 (d, JH−P = 3.47 Hz, 3H) and 1.64 (d, JH−P
= 3.47 Hz, 3H), 1.99 (bs, 2H), 4.17−4.20 (m, 2H) and 4.18−4.22 (m,
2H), 7.46−7.50 (m, 4H), 7.51−7.57 (m, 2H), 7.71−7.78 (m, 4H); 13C
NMR (125 MHz, CDCl3) δ 5.7 and 6.0 (d, JC−P = 38.3 Hz), 17.8 (d,
JC−P = 5.5 Hz), 17.8 (d, JC−P = 3.6 Hz), 66.4 (d, JC−P = 40.9 Hz), 66.5
(d, JC−P = 41.8 Hz), 125.9 and 127.1 (d, JC−P = 51.8 Hz), 128.7 and
128.9 (d, JC−P = 10.0 Hz), 131.67 (d, JC−P = 2.7 Hz), 131.7 (d, JC−P
=
1.8 Hz), 132.1 (d, JC−P = 9.1 Hz), 132.6 (d, JC−P = 9.1 Hz); 31P NMR
(202 MHz, CDCl3) δ 18.14 (m). Anal. Calcd for C9H16BOP: C, 59.39;
H, 8.86. Found: C, 59.22; H, 8.85.
Di-c-hexyl(1-hydroxyethyl)phosphine−Borane (7k). According to
the general procedure, 4k (0.129 g, 0.5 mmol) was treated with BH3·
THF (1.5 mL, 1.5 mmol) and stirred at room temperature for 24 h.
The reaction afforded product 7k (0.122 g, 95%) as a solid; mp =
77.9−79.1 °C; Rf = 0.60 (hexane/ethyl acetate = 4:1); 1H NMR (500
MHz, CDCl3 ) δ −0.06−0.64 (bm, 3H), 1.21−1.31 (m, 6H), 1.40−
1.42 (m, 4H), 1.49 (dd, JH−H = 7.25 Hz, JH−P = 11.98 Hz, 3H), 1.69−
2.08 (m, 12H), 4.22 (q, JH−H = 6.94 Hz, 1H); 13C NMR (125 MHz,
CDCl3) δ 19.2, 26.0, 26.9, 27.0, 27.02 (d, JC−P = 5.5 Hz), 27.1 (d, JC−P
= 5.5 Hz), 27.3 (d, JC−P = 1.8 Hz), 27.5, 27.6 (d, JC−P = 2.7 Hz), 27.8,
o-Anisyl(1-hydroxyethyl)phenylphosphine−Borane (7a). Accord-
ing to the general procedure, 4a (0.131 g, 0.5 mmol) was treated with
BH3·SMe2 (0.142 mL, 1.5 mmol) and stirred at 60 °C for 24 h and
afforded 7a (0.119 g, 92%) as a mixture of two diastereoisomers (dr =
63:37). Both diastereoisomers were separated and characterized. Major
diastereoisomer (0.048 g, 37%): solid; mp = 109.9−110 °C; Rf = 0.58
1
(hexane/ethyl acetate = 2:1); H NMR (500 MHz, CDCl3 ) δ 0.50−
1.26 (bm, 3H), 1.34 (dd, JH−H = 6.62 Hz, JH−P = 15.13 Hz, 3H), 2.34
(bs, 1H), 3.76 (s, 3H), 5.16−5.21 (m, 1H), 6.91−6.94 (m, 1H), 7.06−
7.10 (m, 1H), 7.37−7.47 (m, 3H), 7.51−7.54 (m, 1H), 7.73−7.76 (m,
2H), 7.83−7.87 (m, 1H); 13C NMR (125 MHz, CDCl3) δ 18.9 (d,
JC−P = 9.1 Hz), 55.6, 64.9 (d, JC−P = 41.8 Hz), 111.2 (d, JC−P = 4.5
Hz), 115.5 (d, JC−P = 50.9 Hz), 121.6 (d, JC−P = 11.8 Hz), 128.3 (d,
JC−P = 10.0 Hz), 128.4 (d, JC−P = 56.3 Hz), 130.8 (d, JC−P = 2.7 Hz),
132.3 (d, JC−P = 9.1 Hz), 133.9, 136.7 (d, JC−P = 12.7 Hz), 160.8; 31P
NMR (202 MHz, CDCl3) δ 25.28 (m, major). Anal. Calcd for
C15H20BO2P: C, 65.73; H, 7.35. Found: C, 65.35; H, 7.43. Minor
diastereoisomer (0.044 g, 34%): oil; Rf = 0.52 (hexane/ethyl acetate =
30.4 (d, JC−P = 29.1 Hz), 30.61 (d, JC−P = 29.1 Hz), 62.5 (d, JC−P
=
36.3 Hz); 31P NMR (202 MHz, CDCl3) δ 32.27 (m). Anal. Calcd for
C14H30BOP: C, 65.64; H, 11.80. Found: C, 65.33; H, 12.00.
(1-Hydroxy-2-methylpropyl)diphenylphosphine−Borane (8m).
According to the general procedure, 5m (0.137 g, 0.5 mmol) was
treated with BH3·SMe2 (142 μL, 1.5 mmol) and stirred at room
temperature for 24 h. The reaction afforded product 8m (0.126 g,
93%) as an oil; Rf = 0.84 (hexane/AcOEt = 2:1). 1H NMR (500 MHz,
CDCl3) δ 0.70−1.30 (bm, 3H), 0.89 (d, JH−P = 6.94 Hz, 3H), 0.96 (d,
JH−P = 6.62 Hz, 3H), 2.11 (bs, 1H), 2.20 (sept, 1H), 4.47 (ms, 1H),
7.43−7.50 (m, 6H), 7.74−7.78 (m, 2H), 7.87−7.91 (m, 2H); 13C
NMR (125 MHz, CDCl3) δ 17.0 (d, JC−P = 4.5 Hz), 21.3 (d, JC−P = 8.2
1
2:1); H NMR (500 MHz, CDCl3) δ 0.53−1.26 (bm, 3H), 1.42 (dd,
JH−H = 6.94 Hz, JH−P = 15.45 Hz, 3H), 2.78 (bs, 1H), 3.77 (s, 3H),
4.97−5.01 (m, 1H), 6.99−7.01 (m, 1H), 7.13−7.16 (m, 1H), 7.38−
Hz), 30.8 (d, JC−P = 7.3 Hz), 75.0 (d, JC−P = 36.3 Hz), 127.7 (d, JC−P
=
L
J. Org. Chem. XXXX, XXX, XXX−XXX