Scope and Limitations of the Peterson Olefination Reaction
FULL PAPER
this mixture was stirred for 2 h. A large excess of paraformaldehyde
(6.40 g, 0.21 mol) was added and the mixture was stirred for 1 h.
The reaction was then quenched with deoxygenated water (30 mL)
and the organic layer was extracted into diethyl ether (3 ϫ 20 mL)
room temperature and was stirred for 12 h. Deoxygenated water
(50 mL) was added and the organic layer was dried with activated
4-A molecular sieves. Solvent was removed in vacuo to give
(nPr2P)(Me3Si)2CH. This phosphane (2.60 g, 9.41 mmol) was dis-
solved in dichloromethane (10 mL), treated with elemental sulfur
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and dried with activated 4-A molecular sieves. Solvent was removed
in vacuo to give 6 as a pale yellow oil. Isolated yield 8.97 g, 75%. (0.30 g, 9.41 mmol) and stirred for 2 h. Solvent was removed in
C11H28BPSi (230.2): calcd. C 57.39, H 12.26; found C 57.34, H vacuo and the product was dissolved in THF (20 mL), treated with
12.00. 1H NMR (CDCl3, 27 °C): δ ϭ 0.24 (s, 9 H, SiMe3), nBuLi (3.76 mL, 9.40 mmol) and stirred for 2 h. A large excess of
0.98Ϫ1.70 (m, 14 H, Pr), 6.38 (dd, JH,H ϭ 3, 3JPH ϭ 44 Hz, 1 H, ϭ
paraformaldehyde (1.41 g, 0.044 mol) was added and this mixture
CH2), 6.57 (dd, JH,H ϭ 3, 3JPH ϭ 27 Hz,1 H, ϭCH2) ppm. 13C{1H} was stirred for 1 h. The reaction was then quenched with deoxygen-
NMR (CDCl3, 27 °C): δ ϭ 0.00 (SiMe3), 15.58 (Pr), 16.46 (Pr), ated water (30 mL) and the organic layer was extracted with diethyl
27.10 (Pr), 144.47 (ϭCH2) ppm. 31P{1H} NMR (CDCl3, 25 °C): ether (3 ϫ 20 mL) and dried with activated 4-A molecular sieves.
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δ ϭ 21.9 (br) ppm.
Solvent was removed in vacuo to give 10 as a pale yellow oil. Iso-
1
lated yield 1.86 g, 65%. H NMR (CDCl3, 27 °C): δ ϭ 0.04 (s, 9
Preparation of (Ph2P)(iPr2P)C؍
CH2 (7): To a solution of methyldi-
phenylphosphane (4.10 g, 20.48 mmol) in diethyl ether (30 mL) was
added nBuLi (8.36 mL, 20.48 mmol) and this mixture was left to
stir for approximately 1 h. To this orange/yellow solution was ad-
ded, dropwise, a solution of tBuOK (2.30 g, 20.48 mmol) in diethyl
ether (30 mL). The yellow precipitate was isolated by filtration and
washed with diethyl ether (3 ϫ 15 mL) and residual solvent was
removed in vacuo. The solid was dissolved in THF (30 mL) and
added to a cold (Ϫ78 °C) solution of chlorodiisopropylphosphane
(2.92 mL, 18.38 mmol) in THF (20 mL). The solvent was removed
in vacuo to give a viscous brown oil which was dissolved in light
petroleum (40 mL) and washed with deoxygenated water (3 ϫ
3
H, SiMe3), 0.76Ϫ1.55 (m, 14 H, Pr), 6.23 (dd, JH,H ϭ 3, JPH
ϭ
3
51 Hz, 1 H, ϭCH2), 6.67 (dd, JH,H ϭ 3, JPH ϭ 34 Hz, 1 H, ϭ
CH2) ppm. 13C{1H} NMR (CDCl3, 27 °C): δ ϭ 0.54 (SiMe3), 15.26
(Pr), 16.01 (Pr), 35.17 (Pr), 146.20 (ϭCH2) ppm. 31P{1H} NMR
(CDCl3, 25 °C): δ ϭ 52.3 ppm.
Preparation of [Ph2P(S)][iPr2P(S)]C؍
CH2 (11): To a solution of
the diphosphane (Ph2P)(iPr2P)CH2 (3.64 g, 11.51 mmol; see 7
above) in dichloromethane (40 mL) was added elemental sulfur
(0.738 g, 11.51 mmol) and this solution was stirred for 2 h. Solvent
was removed in vacuo and the white solid was dissolved in THF
(20 mL), treated with nBuLi (4.60 mL, 11.51 mmol) and left to stir
for 12 h. The deep orange solution was then added, dropwise, to a
cold (Ϫ78 °C) solution of chlorotrimethylsilane (1.49 mL,
11.51 mmol) in diethyl ether (10 mL). The solution was allowed to
attain room temperature and was treated with a further equivalent
of nBuLi (4.60 mL, 11.51 mmol) and stirred for 12 h. To the re-
sulting solution was added solid paraformaldehyde (1.63 g,
54.15 mmol) and diethyl ether (20 mL) and the mixture was al-
lowed to stir for 1 h before deoxygenated water (30 mL) was added.
The organic phase was decanted, the aqueous layer was extracted
into diethyl ether (3 ϫ 10 mL) and the combined organic extracts
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20 mL). The organic layer was dried with activated 4-A molecular
sieves and solvent was removed in vacuo to give the diphosphane
(Ph2P)(iPr2P)CH2 as a colorless oil.
To a solution of the diphosphane (Ph2P)(iPr2P)CH2 (3.66 g,
11.57 mmol) in diethyl ether (40 mL) was added BH3·SMe2
(11.57 mL, 23.14 mmol) and this solution was stirred for 1 h. THF
(20 mL) was added, followed by nBuLi (5.03 mL, 11.57 mmol) and
the solution was left to stir for 12 h. The deep orange solution was
added dropwise to a cold (Ϫ78 °C) solution of chlorodimethylsil-
ane (1.28 mL, 11.57 mmol) in diethyl ether (10 mL). The solution
was allowed to attain room temperature and was treated with
nBuLi (5.03 mL, 11.57 mmol) and stirred for 12 h. To the resulting
solution was added paraformaldehyde (1.63 g, 54.15 mmol) and di-
ethyl ether (20 mL), the mixture was allowed to stir for 1 hour and
then deoxygenated water (30 mL) was added. The organic layer was
decanted, the aqueous layer was extracted into diethyl ether (3 ϫ
10 mL) and the combined organic extracts were dried with acti-
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were dried with activated 4-A molecular sieves. The solution was
filtered and solvent was removed in vacuo to give a colorless oil
which yielded 11 as a white crystalline solid on addition of ethanol
(20 mL). Isolated yield 2.10 g, 53% (based on Ph2PMe).
C20H26P2S2 (392.5): calcd. C 61.20, H 6.81; found C 60.51, H 6.81.
3
1H NMR (CDCl3, 25 °C): δ ϭ 0.72 [dd, JH,H ϭ 7, JPH ϭ 19 Hz,
3
6 H, CH(CH3)2], 1.08 [dd, JH,H ϭ 7, JPH ϭ 19 Hz, 6 H,
CH(CH3)2], 3.07 [m, 2 H, CH(CH3)2], 6.34 (ddd, JH,H ϭ 1, 3JPH ϭ
22, 3JPH ϭ 37 Hz, 1 H, ϭCH2), 7.40Ϫ7.50 (m, 6 H, Ph), 7.52 (ddd,
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vated 4-A molecular sieves. The dried solution was filtered and sol-
3
3
vent was removed in vacuo and a small amount of light petroleum
was added, yielding an off-white, crystalline solid. This solid was
dissolved in pyrrolidine (8.23 g, 0.115 mol) and the solution was
stirred overnight. Excess pyrrolidine was removed in vacuo and the
residue was distilled under reduced pressure (oil bath temperature
JH,H ϭ 1, JPH ϭ 22, JPH ϭ 37 Hz, 1 H, ϭCH2), 7.67Ϫ7.71 (m,
4 H, Ph) ppm. 13C{1H} NMR (CDCl3, 25 °C): δ ϭ 17.89
[CH(CH3)2], 18.18 [CH(CH3)2], 28.89 [CH(CH3)2], 128.72, 130.97,
131.84, 136.26 (Ph), 150.93 (ϭCH2) ppm. 31P{1H} NMR (CDCl3,
25 °C): δ ϭ 42.4 [d, JP,P ϭ 26 Hz, P(S)Ph2], 84.0 (d, JP,P ϭ 26 Hz,
P(S)iPr2) ppm.
150 °C, 0.01 Torr) to give 7 as a colorless oil. Isolated yield 2.85 g,
72%. 1H NMR (CDCl3, 25 °C): δ ϭ 0.94 [dd, JH,H ϭ 7, JP,P
ϭ
3
Preparation of [Ph2P(S)][Me2P(S)]C؍
CH2 (12): To a solution of
trimethylphosphane (2.31 g, 30.66 mmol) in light petroleum
(30 mL) was added tBuLi (18.04 mL, 30.66 mmol) and this mixture
was stirred for 12 h. The resulting precipitate was isolated by fil-
tration, washed with light petroleum (3 ϫ 15 mL) and dried in va-
cuo. The solid was dissolved in THF (30 mL) and added to a cold
(Ϫ78 °C) solution of chlorodiphenylphosphane (4.63 mL,
25.81 mmol) in THF (20 mL). The solvent was removed in vacuo
to give a straw-colored oil which was dissolved in light petroleum
(40 mL) and washed with deoxygenated water (3 ϫ 20 mL). The
3
13 Hz, 6 H, CH(CH3)2], 1.03 [dd, JH,H ϭ 7, JP,P ϭ 13 Hz, 6 H,
CH(CH3)2], 1.95 [m, 2 H, CH(CH3)2], 5.58 (ddd, JH,H ϭ 2, 3JPH ϭ
3
3
9, JPH ϭ 19 Hz, 1 H, ϭCH2), 6.06 (ddd, JH,H ϭ 2, JPH ϭ 10,
3JPH ϭ 19 Hz, 1 H, ϭCH2), 7.26 (m, 10 H, Ph) ppm. 13C{1H}
NMR (CDCl3, 25 °C): δ ϭ 19.57 [CH(CH3)2], 22.82 [CH(CH3)2],
53.67 [CH(CH3)2] 128.10, 128.53, 134.13, 135.76 (Ph), 150.93 (ϭ
CH2) ppm. 31P{1H} NMR (CDCl3, 25 °C): δ ϭ Ϫ4.4 (d, JP,P
102 Hz, PiPr2), 15.4 (d, JP,P ϭ 102 Hz, PPh2) ppm.
ϭ
Preparation of [nPr2P(S)](Me3Si)C؍
CH2 (10): To a cold (Ϫ78 °C)
solution of (Me3Si)2CHPCl2 (3.07 g, 11.76 mmol) in diethyl ether
(100 mL) was added, dropwise, a solution of nPrMgCl in diethyl
ether (11.76 mL, 23.52 mmol). The solution was allowed to attain
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organic phase was dried with activated 4-A molecular sieves and
solvent was removed in vacuo to give the diphosphane
(Ph2P)(Me2P)CH2 as a colorless oil.
Eur. J. Org. Chem. 2004, 1043Ϫ1048
2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1047