Reactions of t-butylphosphine-borane with various electrophiles and synthesis of optically active t-butylmethylphosphine-borane

Article abstract of DOI:10.1246/bcsj.75.1359

The reactivity of t-butylphosphine-borane toward various electrophiles was studied with a focus on alkylation. Monoalkylation of this compound proceeded smoothly in good yields (61-85%). Disubstituted derivatives were also synthesized in good yields (86-99%). Optically active t-butylmethylphosphine-borane was prepared from t-butylphosphine-borane by resolution of intermediate diastereomers of (1S)-endo-2-bornyloxycarbonyl(t-butyl)methylphosphineborane.

Full text of DOI:10.1246/bcsj.75.1359

c. Jpn.
© 2002 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 75, 1359–1365 (2002) 1359
e Chemical
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Reactions of t-Butylphosphine–Borane with Various Electrophiles and
Synthesis of Optically Active t-Butylmethylphosphine–Borane
Reactions of t-Butylphosphine–Borane
N. Oohara et al.
Nobuhiko Oohara and Tsuneo Imamoto*,†
02
59
65
Research & Development Division, Nippon Chemical Industrial Co., Ltd.,
11-1, 9-chome, Kameido, Koto-ku, Tokyo 136-8515
SJA8
09-2673
423
†Department of Chemistry, Faculty of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522
(Received November 26, 2001)
01
The reactivity of t-butylphosphine–borane toward various electrophiles was studied with a focus on alkylation.
Monoalkylation of this compound proceeded smoothly in good yields (61–85%). Disubstituted derivatives were also
synthesized in good yields (86–99%). Optically active t-butylmethylphosphine–borane was prepared from t-butylphos-
phine–borane by resolution of intermediate diastereomers of (1S)-endo-2-bornyloxycarbonyl(t-butyl)methylphosphine-
borane.
02
1
Optically active phosphines have become increasingly im-
portant as chiral ligands in various transition metal-catalyzed
asymmetric reactions,1 and numerous phosphines of this class
have been reported.1,2 Among them, some P-chirogenic tri-
alkyl bisphosphine ligands exhibit high catalytic activity and
enantioselectivity.3
Although these phosphine ligands are usually conveniently
prepared from trichlorophosphine or alkyldichlorophos-
phines,4 primary alkylphosphines5 derived from PH3 may also
contribute valuable starting materials for the synthesis of phos-
phine ligands.
dled in air, while it gradually decomposes on contact with
moisture. A weak P–B bond may be responsible for this sensi-
tiveness to moisture. The strength of this bond can be estimat-
ed by the value of the coupling constant between phosphorus
and boron in NMR analysis (JPB).9 The values of the JPB in
other primary alkylphosphine–boranes were reported (e.g.
phenylphosphine–borane (38.4 Hz), methylphosphine–borane
(41.8 Hz)).10 The observed JPB of 1 in this study was 35.2 Hz
(literature 32 Hz).11 These relatively smaller JPB values are
compared with larger values of tertiary phosphine–boranes
which are more stable than primary phosphine–borane.
Recently, we have developed a new synthetic route to enan-
tiomerically enriched6 or pure7 dialkylphosphine–boranes hav-
ing a P–H bond, which are useful chiral building blocks for the
synthesis of bisphosphine ligands. However, the former meth-
od provides only one of the enantiomer ligands and the latter
cannot be carried out in large scale separation of the key inter-
mediate diastereomers by recrystallization. Therefore, a new
efficient method is still strongly required for the synthesis of
both enantiomer ligands.
Scheme 1.
In this study we prepared t-butylphosphine–borane from t-
butylphosphine and examined its reactivity toward various
electrophiles in order to explore a new route to optically active
t-butylmethylphosphine–borane.
Synthesis of Monosubstituted Derivatives of 1.
Com-
pound 1 was subjected to deprotonation with 1 equivalent of n-
BuLi at −78 °C. The generated lithium derivative was allowed
to react with 1.1 equivalents of electrophile to give the corre-
sponding monosubstituted derivative (Scheme 2). These re-
sults are summarized in Table 1.
Results and Discussion
Synthesis of t-Butylphosphine–Borane. As a representa-
tive example of primary alkylphosphine, we selected t-bu-
tylphosphine, because this phosphine is prepared on industrial
scale from phosphine and isobutene.8 Another reason is that
bisphosphine ligands bearing a t-butyl substituent exhibit ex-
cellent enantioselectivity in transition metal-catalyzed asym-
metric reactions.3a,3b
Scheme 2.
Its borane complex was prepared almost quantitatively by
reaction of t-butylphosphine with stoichiometric quantities of
BH3–THF complex (Scheme 1). This compound can be han-
Reactions with alkyl halides proceeded smoothly to give the
corresponding secondary dialkylphosphine-boranes in good

1360 Bull. Chem. Soc. Jpn., 75, No. 6 (2002)
Table 1. Synthesis of Monosubsutituted Derivatives of 1
Reactions of t-Butylphosphine–Borane
Entrya)
Electrophile
CH3I
n-C4H9Cl
n-C14H29Cl
PhCH2Cl
Product
Yield%d)
1
2
3
4
t-BuCH3PH(BH3) (2a)
85
65
74
61
t-Bu(n-C4H9)PH(BH3) (2b)
t-Bu(n-C14H29)PH(BH3) (2c)
t-Bu(PhCH2)PH(BH3) (2d)
34 (rac) (2e)
32 (meso) (2f)
5
6
7
(+)-Men*OCOClb)
PhSSPh
t-Bu(Men*OCO)2PBH3 (2g)
t-Bu(PhS)2P (2h)
18e)
13
8
9
10
ClCH2COOC2H5
t-BuPH(BH3)CH2COOC2H5 (2i)
34
75
67
ClCH2COOMen* b) t-BuPH(BH3)CH2COOMen* (2j)
ClCH2COOBor* c)
t-BuPH(BH3)CH2COOBor* (2k)
a) All the reactions were carried out according to Scheme 2. b) Men = menthyl.
c) Bor = bornyl. d) Isolated yield. e) Crude product.
yields (Table 1, entries 1–5, 61–85%) with small amounts of
dialkylation products (ca. < 10%). On the other hand, reac-
tion of (+)-menthyl chloroformate or diphenyl disulfide with
compound 1 offered no appreciable amount of monosubstitut-
ed derivatives but only low yields of disubstituted derivatives
(entries 6, 7). TLC analyses of these reaction mixtures showed
that disubstitution occurred from the beginning of the reac-
tions, suggesting that the acidity of the P–H bond in monosub-
stituted derivatives increases with the substitution of the carbon-
yl or phenylthio component.
The reactivity of the lithium salt of 1 toward substrates bear-
ing a carbonyl group, such as benzophenone and cyclohex-
anone, was also investigated. However, these reactions pro-
ceeded sluggishly, and the corresponding α-hydroxyalkylphos-
phine-borane derivatives could not be obtained.
Fig. 1. ORTEP drawing of t-BuPH2–BH2–t-BuPH–BH3 (3)
Hydrogen atoms are omitted for clarity.
Dehydrocoupling Dimer of 1. In order to obtain phenyl
derivative of 1, we tried cross-coupling reactions with 1 and io-
dobenzene as well as phenyl triflate using transition-metal cat-
alysts in the presence of base but our efforts were unsuccess-
ful. However, in the process of these trials, we found that an
interesting compound was produced in low yield. This com-
pound was isolated and characterized by NMR, HRMS, and X-
ray crystallographic analysis as being the dehydrocoupling
dimer (3) possessing a P–B–P bond linkage as depicted in Fig.
1. The geometry around P1, B2, and P2 is approximately tet-
rahedral with slightly opened B1–P1–B2 angle and C5–P2–B2
angle (117.3(7)° and 115.3(8)°, respectively) and slightly
closed P1–B2–P2 angle (103.0(1)°). In contrast to the bond
length of B1–P1 (1.93 Å), which is a typical value of phos-
phine–borane complexes,12 P1–B2 (1.97 Å) and B2–P1 (2.00
Å) bond lengths are a little longer.
Scheme 3.
Scheme 4.
Recently, Manners and co-workers have reported the syn-
thesis of this type of dehydrocoupling compounds by use of
transition-metal catalyzed reactions.13,14,15 Encouraged by
their results, we performed the previous experiment by rhodi-
um-catalyzed reaction using complexes such as [RhCl(nbd)]2,
[Rh(t-BuBisP*)(nbd)]+BF4−. However, this dimer could not
be obtained. The best result was realized by employing 10
mol% of NiCl2 (ca. 12%, Scheme 3).
yields of disubstituted compounds (2g, 2h) led us to investi-
gate the syntheses of this type of compounds, as shown in
Scheme 4.
Compound 1 was slowly added to a mixture of NaH (3
equivalents) and electrophile (2.2 equivalents) in THF at −20
°C. Upon addition, the reaction mixture was allowed to warm
to 0 °C and stirred for several hours until consumption of the
starting material was complete.
Synthesis of Disubstituted Derivatives of 1.
The low
Results summarized in Table 2 show that the corresponding

N. Oohara et al.
Bull. Chem. Soc. Jpn., 75, No. 6 (2002) 1361
Table 2. Synthesis of Disubsutituted Derivatives of 1
Entrya)
Electrophile
CH3I
n-C4H9Cl
Product
Yield%c)
1
2
3
4
5
6
t-Bu(CH3)2PBH3 (4a)
94
88
97
99
t-Bu(n-C4H9)2PBH3 (4b)
t-Bu(n-C14H29)2PBH3 (4c)
t-Bu(PhCH2)2PBH3 (4d)
t-Bu(Men*OCO)2PBH3 (2g)
t-Bu(PhS)2P (2h)
n-C14H29Cl
PhCH2Cl
(+)-Men*OCOClb)
PhSSPh
92d)
96
a) All the reactions were carried out according to Scheme 4. b) Men = men-
thyl. c) Isolated yield. d) Crude product.
disubstituted compounds of 1 were isolated in high yields (88–
99%). Another notable fact is that t-butyldimethylphosphine–
In order to overcome their difficulty, we designed an alter-
native three step strategy (Scheme 5): (i) conversion of racemic
t-butylmethylphosphine–borane (2a) to diastereomers by in-
troducing chiral auxiliary, (ii) separation of diastereomers by
recrystallization, and (iii) hydrolysis and decarboxylation of
the separated diastereomer to recover each pure enantiomer.
Thus, racemic 2a was allowed to react with (+)-menthyl
chloroformate to give 1:1 mixture of corresponding diastere-
omers (5) in 65% yield. However, attempts to separate these
diastereomers by recrystallization failed owing to the fact that
5 was obtained as pasty oil.
On the other hand, the (1S)-endo-2-bornyl chloroformate
derivative (6), prepared from (−)-borneol and racemic 2a in
70% yield, was isolated as a crystalline solid (1:1 mixture of
diastereomers). A few recrystallizations from hexane provided
(6a) (95% de20), one of the diastereomers, in 32% yield.21
Transformation of diastereomerically enriched 6a into t-bu-
tylmethylphosphine-borane was achieved by hydrolysis and
decarboxylation. Table 3 shows summarized results. After
screening several base/solvents, the best compromise between
yield and ee was achieved when the starting material was treat-
ed with a large excess of KOH (20 equivalents) at room tem-
perature (Table 3, entry 5). Under these conditions, (S)-t-bu-
tylmethylphosphine–borane was obtained in 75% yield with-
out any loss of enantiomeric purity (95% ee).
3a
borane (4a), key intermediate for the preparation of BisP*
and MiniPHOS,3b was isolated in excellent 94% yield (Table 2,
entry 1).
Synthesis of Optically Active t-Butylmethylphosphine–
Borane. Finally, we examined the synthesis of optically ac-
tive secondary dialkylphosphine–borane. At first, a one pot
synthesis was performed by deprotonation of precursor 1 using
n-BuLi/(−)-sparteine complex,16 followed by trapping with
benzyl chloride. Specific rotation measurements or chiral-
HPLC analyses of these products showed no significant differ-
ences as compared to their racemates, indicating that prochiral
P–H bonds of primary alkylphosphine–borane cannot be stere-
oselectively deprotonated by this method.
The dynamic resolution method, reported by Livinghouse et
al.17 was also examined under even more forcing conditions,
but afforded no success.
Our attention was turned to the optical resolution of inter-
mediate diastereomers prepared from 1 and chiral auxiliary.
Although the yield was only moderate, the successful intro-
duction of alkoxycarbonylmethyl group to phosphorus atom of
1, as a test experiment (Table 1, entry 8), led us to the synthesis
of chiral analogues, namely the (−)-menthyl and (−)-bornyl
derivatives.18 To our surprise, the isolated yields of diastere-
omers 2j and 2k increased to 75% and 67%, respectively (Ta-
ble 1, entries 9, 10). Unfortunately, their separation by recrys-
tallization proved unsuccessful.19
Experimental
General. All pieces of glassware were dried in an oven be-
Scheme 5.

1362 Bull. Chem. Soc. Jpn., 75, No. 6 (2002)
Reactions of t-Butylphosphine–Borane
Table 3. Hydrolysis–Decarboxylation of 6a
Entry Temp/°C
50
Conditions
conc. HCl/MeOH, 1h
Yield%
eef)/%
1a)
traced)
45
—
84
—
95
95
2a)
3a)
4b)
5b)
50
r.t.
r.t.
r.t.
KOH (5 equiv)/MeOH, 3h
KOH (10 equiv)/CH3CN/H2O,c) 1h
KOH (15 equiv)/CH3CN/MeOH/H2O, 4h
KOH (20 equiv)/CH3CN/MeOH/H2O, 4h
—
e)
64
75
a) 84% de of 6a was used. b) 95% de of 6a was used. c) Reaction was performed under the same
conditions that we previously reported,6 without oxidation reagents. d) TLC analysis. e) Because
6a was insoluble in this solvent system, the reaction was aborted. f) The ee (%) values were deter-
mined by HPLC analysis using Chiral Daicel OD-H column on the corresponding 2-pyridylmethyl
derivative.6,7
fore use. Dehydrated, stabilizer-free THF was purchased from
1.33 (dd, 2JHP = 10.7 Hz, J = 6.0 Hz, 3H), 4.41 (dm, JHP = 354.8
Hz, 1H); 13C NMR (75.4 MHz, CDCl3) δ 2.1 (d, JCP = 34.8 Hz),
26.0 (d, JCP = 34 Hz), 26.2 (d, 2JCP = 3.0); 31P NMR (121.5 MHz,
1H decoupled, CDCl3 ) δ −12.1 (br q, JPB = 51.4 Hz); IR (KBr)
2970, 2380, 1463 cm−1; HRMS EI m/z 117.1009. Calcd for
C5H15BP (M+−H) 117.1005.
Kanto Kagaku Co., Ltd., and was used as the reaction solvent. t-
Butylphosphine (exact 10 wt% solution of hexane) was supplied
by Shin-Etsu Chemical Co., Ltd. Reactions were carried out un-
der argon atmosphere. Reaction products were purified by flash
column chromatography on silica gel (Wakogel C-200 or C-300),
unless otherwise stated. 1H, 13C, and 31P NMR spectra were re-
corded on a JMN-LA300 spectrometer (JEOL). Chemical shifts
are referenced to solvent peaks or internal TMS (1H, 13C), or exter-
nal 85% H3PO4 (31P). High-resolution mass spectra were obtained
on a JMS-DX303 mass spectrometer (JEOL). FT-IR spectra were
obtained on a FT/IR-430 spectrometer (JASCO). Melting points
were determined with MP-V500 (Yanako) or FP-62 (Mettler Tle-
do). Specific rotation was obtained on SEPA-300 polarimeter
(HORIBA). TLC were performed on glass plates precoated with
silica gel 60 F-254 (0.2 mm) from Merck.
Butyl(t-butyl)phosphine–Borane (2b). This compound was
prepared from 1 and butyl chloride in 65% yield (2 mmol scale)
1
and isolated as colorless oil. H NMR (300.4 MHz, CDCl3) δ 0.47
(br q, JHB = 98.7 Hz, 3H), 0.94 (t, J = 6.8 Hz, 3H), 1.22 (d, 3JHP
= 14.1 Hz, 9H), 1.34–1.60 (m, 4H), 1.58–1.90 (m, 2H), 4.23 (dm,
JHP = 350.5 Hz, 1H); 13C NMR (75.4 MHz, CDCl3) δ 13.7, 17.4
3
(d, JCP = 31 Hz), 24.2 (d, JCP = 12.5 Hz), 26.4 (d, JCP = 35.4
2
3
Hz), 26.6 (d, JCP = 1.9 Hz), 27.2 (d, JCP = 1.9 Hz); 31P NMR
(121.5 MHz, 1H decoupled, CDCl3 ) δ 23.4 (br q, JPB = 48.6 Hz);
IR (KBr) 2958, 2383, 1465 cm−1; HRMS EI m/z 146.1201. Calcd
for C8H19P (M+−BH3) 146.1224.
t-Butylphosphine–Borane (1). t-Butylphosphine was stored
in well-sealed SUS bottle as 10 wt% hexane solutions. From this
bottle, 91.0 g of this solution (101 mmol) was transferred to 500
mL flask under argon atmosphere via syringe. BH3–THF complex
(100 mL of 1.01 M THF solution, 101 mmol) was slowly added at
0 °C and the resulting mixture was stirred for 1 h at this tempera-
ture. The solvents were removed under vacuum and the residue
was distilled in vacuo to give t-butylphosphine–borane as a color-
t-Butyl(tetradecyl)phosphine–Borane (2c).
This com-
pound was prepared from 1 and tetradecyl chloride in 74% yield
(2 mmol scale) and isolated as white pasty oil. 1H NMR (300.4
3
MHz, C6D6) δ 0.93 (d, JHP = 9.3 Hz, 9H), 0.96 (t, J = 6.8 Hz,
3H), 1.1–1.7 (m, 29 H), 3.92 (dm, JHP = 346.4 Hz, 1H); 13C NMR
(75.4 MHz, C6D6) δ 14.4, 17.7 (d, JCP = 31.0 Hz), 23.1, 25.2,
2
26.1, 26.6 (d, JCP = 1.9 Hz), 29.6, 29.86, 29.94, 30.10, 30.17,
1
1
less liquid (10.42 g, 99%). Bp 31–32 °C /6 mmHg; H NMR
30.20, 31.2, 31.3, 32.4; 31P NMR (121.5 MHz, H decoupled,
(300.4 MHz, C6D6) δ 0.93 (d, 3JHP = 15.2 Hz, 9H), 1.04 (br q, JHB
C6D6) δ 22.7–23.8 (m); IR (KBr) 2933, 2853, 2384, 1464 cm−1
;
= 101.5 Hz, 3H), 3.93 (dm, JHP = 352.7 Hz, 2H); 13C NMR (75.4
HRMS EI m/z 286.2826. Calcd for C18H39P (M+−BH3)
MHz, C6D6) δ 25.2 (d, JCP = 34.7 Hz), 27.8 (d, 2JCP = 3.1 Hz); 31
P
=
286.2790.
1
NMR (121.5 MHz, H decoupled, C6D6) δ −11.9 (br q, JPB
Benzyl(t-butyl)phosphine–Borane (2d).
This compound
35.2 Hz); IR (KBr Plate) 2961, 2396, 1461 cm−1; HRMS EI m/z
103.0845. Calcd for C4H13BP (M+−H) 103.0848.
was prepared from 1 and benzyl chloride in 61% yield (2 mmol
scale) and isolated as white pasty oil. 1H NMR (300.4 MHz,
CDCl3) δ 0.50 (br q, JHB = 98.2 Hz, 3H), 1.24 (d, 3JHP = 9.6 Hz,
9H), 2.9–3.3 (m, 2 H), 4.73 (dm, JHP = 357.3 Hz, 1H); 13C NMR
(75.4 MHz, CDCl3) δ 25.9 (d, JCP = 28.6 Hz), 26.8 (d, 2JCP = 1.9
Hz), 31.0 (d, 2JCP = 31.0 Hz), 127.0 (d, J = 2.5 Hz), 128.8 (d, J =
2.5 Hz), 129.4 (d, J = 4.4 Hz), 130.2 (d, J = 4.4 Hz); 31P NMR
(121.5 MHz, 1H decoupled, CDCl3 ) δ 31.2 (br q, JPB = 55.9 Hz);
IR (KBr) 3030, 2956, 2389, 1457, 1368 cm−1; HRMS EI m/z
194.1402. Calcd for C11H20BP (M+) 194.1396.
Synthesis of Monosubstituted Derivatives of 1.
t-Butyl-
(methyl)phosphine–Borane (2a). A representative experimen-
tal procedure is described for t-butylmethylphosphine–borane.
To a stirred, cooled (−78 °C) solution of 1 (3.91 g, 37.7 mmol)
in THF (120 mL) was slowly added n-BuLi (26 mL of 1.50 M
hexane solution, 39 mmol) under argon atmosphere. After 10
min, CH3I (5.88 g, 41.4 mmol) was slowly added at −78 °C. The
resulting mixture was stirred for 1 h at this temperature then at
room temperature. To this reaction mixture was carefully added
iced water containing HCl. The organic layer was separated and
the aqueous layer was extracted with Et2O three times. The com-
bined extracts were washed with water and brine, dried (Na2SO4),
and concentrated. The residue was distilled in vacuo to give t-bu-
tylmethylphosphine–borane as a white solid (3.78 g, 85%). Mp
33–37 °C; bp 90–91 °C /15 mmHg; 1H NMR (300.4 MHz, CDCl3)
1,2-Bis{[boranato(t-butyl)phosphino]methyl}benzene.
This compound was prepared from 1 and 1,2-bis(chlorometh-
yl)benzene dichloride in 34% yield (racemic), 32% yield (meso)
(5 mmol scale) and isolated as colorless cubes. Racemate com-
pound (2e). Mp 136.0–137.0 °C; 1H NMR (300.4 MHz, CDCl3) δ
3
0.44 (br q, JHB = 110.7 Hz, 6H), 1.32 (d, JHP = 14.4 Hz, 18H),
3.19–3.36 (m, 4H), 4.32 (dm, JHP = 357.4 Hz, 2H), 7.11–7.20 (m,
3
δ 0.49 (br q, JHB = 98.6 Hz, 3H), 1.21 (d, JHP = 14.7 Hz, 9H),
4H); 13C NMR (75.4 MHz, CDCl3) δ 22.6 (d, JCP = 26.7 Hz), 26.7

N. Oohara et al.
Bull. Chem. Soc. Jpn., 75, No. 6 (2002) 1363
2
2
(d, JCP = 1.9 Hz), 27.5 (d, JCP = 31.0 Hz), 127.4–127.6 (m),
130.4–130.5 (m), 133.3–133.5 (m); 31P NMR (121.5 MHz, 1H de-
coupled, CDCl3 ) δ 31.0–33.0 (m); IR (KBr) 3030, 2954, 2867,
2386, 1461, 1367 cm−1; HRMS EI m/z 304.1850. Calcd for
C16H28B2P2 (M+−6H) 304.1852.
CDCl3 ) δ 19.9–20.5 (m); IR (KBr) 2956, 2880, 2394, 2360, 1726,
1474, 1391, 1369, 1284 cm−1; HRMS EI m/z 284.1915. Calcd for
C16H29O2P (M+–BH3) 284.1905.
Dehydrocoupling Dimer of 1 (3). NiCl2 (38.8 mg, 10 mol%)
was added to neat 1 (311.8 mg, 3 mmol) under argon atmosphere.
The mixture was allowed to warm slowly and gas evolution was
observed at about 80 °C. After 1 h, the mixture could no longer be
stirred. It was then diluted with MeOH and passed through a
selite pad to remove insoluble materials. The filtrate was concen-
trated, and purified by flash chromatography on silica gel to give a
1
Meso compound (2f). Mp 130.8–133.2 °C; H NMR (300.4
MHz, CDCl3) δ 0.45 (br q, JHB = 104.2 Hz, 6H), 1.32 (d, 3JHP
=
14.4 Hz, 18H), 2.82–2.93 (m, 2H), 3.46–3.57 (m, 2H), 4.31 (dm,
JHP = 348.0 Hz, 2H), 7.19–7.23 (s, 4H); 13C NMR (75.4 MHz,
CDCl3) δ 22.9 (d, JCP = 27.3 Hz), 26.8 (d, 2JCP = 1.9 Hz), 27.7 (d,
2JCP = 31.0 Hz), 127.6–127.8 (m), 131.4–131.5 (m), 132.1–132.3
1
colorless needle (38.1 mg, 12% yield). Mp 97.8–98.6 °C; H
(m); 31P NMR (121.5 MHz, H decoupled, CDCl3 ) δ 29.0–30.8
NMR (300.4 MHz, CDCl3) δ 0.44 (br q, JHB = 97.2 Hz, 3H), 1.18
(d, 3JHP = 14.3 Hz, 9H), 1.34 (d, 3JHP = 16.4 Hz, 9H), 3.50 (dm,
JHB = 340 Hz, 1H), 4.75 (dm, 2H); 13C NMR (75.45 MHz,
1
(m); IR (KBr) 3030, 2961, 2384, 1463, 1368 cm−1; HRMS EI m/z
306.1969. Calcd for C16H30B2P2 (M+−4H) 306.2008.
X-ray Crystallographic Analysis of 2e.
Lattice constants
CDCl3) δ 26.0 (dd, JCP = 32.3 Hz, 3JCP = 8.7 Hz), 26.5 (dd, JCP
=
and intensity data for 2e were measured using graphite monochro-
mated Cu Kα radiation on a Rigaku AFC7S diffractometer. A
well-shaped monoclinic crystal was obtained by recrystallization
from ethyl acetate: C16H34B2P2; space group C2/c (#15); a =
17.430(4) Å, b = 14.045 (2) Å, c = 18.093(2) Å, β = 107.74(1)°,
V = 4218(1) Å3; Z = 8, D = 0.976 g/cm3; F(000) = 1360; µ(Cu
Kα) = 17.66 cm−1; λ(CuKα) = 1.54178 Å; 3997 reflections mea-
sured, 3251 observed (I > 1.00σ(I)); 182 variables; R = 0.091,
Rω = 0.146, GOF = 1.62.
37.2 Hz, 3JCP = 6.9 Hz), 27.7 (d, 2JCP = 2.5), 28.1 (d, 2JCP = 1.8);
31P NMR (121.5 MHz, 1H decoupled, CDCl3 ) δ −24.5 to −20.0
(m), −14 to −11 (m); IR (KBr) 2965, 2897, 2865, 2362,1469,
1364 cm−1; HRMS EI m/z 206.1694. Calcd for C8H26B2P2 (M+)
206.1696.
X-ray Crystallographic Analysis of 3. Lattice constants and
intensity data for 3 were measured using graphite monochromated
Mo Kα radiation on a Rigaku RAXIS-ꢀ Imaging Plate diffracto-
meter. A well-shaped triclinic crystal was obtained by recrystalli-
zation from diethyl ether: C8H26B2P2; space group P1(#2); a =
13.93(6) Å, b = 17.6(1) Å, c = 6.13(2) Å, β = 102.5(2)°, V =
1433(12) Å3; Z = 4, D = 0.953 g/cm3; F(000) = 456; µ(MoKα)
= 2.62 cm−1; λ(MoKα) = 0.71070 Å; 3450 reflections measured,
2581 observed (I > 5.00σ(I)); 217 variables; R = 0.220, Rω =
0.292, GOF = 7.03.
Ethyl Boranato(t-butyl)phosphinoacetate (2i).
This com-
pound was prepared from 1 and ethyl chloroacetate in 34% yield
(2 mmol scale) and isolated as colorless oil. 1H NMR (300.4
MHz, CDCl3) δ 0.52 (br q, JHB = 100.1 Hz, 3H), 1.25 (d, 3JHP
=
15.2 Hz, 9H), 1.30 (t, J = 7.0 Hz, 3H), 2.6–2.9 (m, 2 H), 4.20 (q,
J = 7.0 Hz, 2H), 4.78 (dm, JHP = 369.1 Hz, 1H); 13C NMR (75.4
MHz, CDCl3) δ 14.0, 25.8 (d, JCP = 26.1 Hz), 26.5 (d, 2JCP = 1.9
Hz), 27.1 (d, 2JCP = 32.9 Hz), 167.7 (d, 2JCP = 5.0 Hz); 31P NMR
Synthesis of Disubstituted Derivatives of 1.
t-Butylbis
(phenylthio)phosphine (2h). representative experimental
A
1
(121.5 MHz, H decoupled, CDCl3 ) δ 19.5–21.0 (m); IR (KBr)
procedure is described for t-butylbis(phenylthio)phosphine.
NaH (260 mg (60% in oil), 6 mmol) was washed with dried
THF three times and then dispersed in 4 mL of THF. Diphenyl
disulfide (960 mg, 4.4 mmol) was added and the solution was
cooled to −20 °C. Compound 1 (208 mg, 2 mmol) was slowly
added and the reaction mixture was allowed to warm to 0 °C in 30
min. The mixture was stirred at this temperature until complete
consuming of the starting material (TLC analysis). This solution
was carefully poured onto ice/water containing HCl, and the or-
ganic layer was separated. The aqueous layer was extracted with
ethyl acetate (three times). The combined extracts were washed
with water and brine, dried (Na2SO4), and concentrated in vacuo.
The residue was purified by flash chromatography on silica gel
eluting with hexane/ethyl acetate to give t-butylbis(phenylth-
io)phosphine as white needles (592 mg, 96% yield). Mp 44–45
°C; 1H NMR (300.4 MHz, C6D6) δ 1.34 (d, 3JHP = 13.5 Hz, 9H),
6.85–7.02 (m, , 6H), 7.48–7.60 (m, 4H); 13C NMR (75.4 MHz,
C6D6) δ 27.9 (d, 2JCP = 16.1 Hz), 36.7 (d, JCP = 27.9 Hz), 127.7,
129.5, 133.9, 135.0; 31P NMR (121.5 MHz, 1H decoupled, C6D6) δ
132.8 (s); IR (KBr) 3057, 2965, 2858, 1576, 1474 cm−1; HRMS
EI m/z 306.0680. Calcd for C16H19PS2 (M+) 306.0664.
t-Butyl(dimenthyloxycarbonyl)phosphine–Borane (2g).
The compound was prepared from 1 and (+)-menthyl chlorofor-
mate (2 mmol scale). After workup, the crude product was puri-
fied by flash chromatography on silica gel eluting with hexane/
ethyl acetate to give 2g as colorless oil (873 mg, 92% yield). Un-
fortunately, 2g rapidly decomposed during this process, making
full characterization by NMR impossible. IR (KBr) 2955, 2884,
1709, 1455, 1370 cm−1; HRMS EI m/z 454.3256. Calcd for
C26H47O4P2 (M+−BH3) 454.3312.
2963, 2870, 2391, 1733, 1464, 1368, 1283 cm−1; HRMS EI m/z
189.1228. Calcd for C8H19BO2P (M+−H) 189.1216.
Menthyl [Boranato(t-butyl)phosphino]acetate (2j, Diastere-
omeric Mixture). This compound was prepared from 1 and
menthyl chloroacetate in 75% yield (2 mmol scale) and isolated as
colorless pasty oil. 1H NMR (300.4 MHz, CDCl3) δ 0.50 (br q,
JHB = 90.0 Hz, 6H), 0.74–0.78 (m, 6H), 0.8–0.9 (m, 2H), 0.88–
0.94 (m, 12H), 0.92–1.14 (m, 4H), 1.25 (d, 3JHP = 15.2 Hz, 18H),
1.30–1.52 (m, 4H), 1.64–1.73 (m, 4 H), 1.83–1.98 (m, 2H), 1.98–
2.09 (m, 2H), 2.63–2.95 (m, 4H), 4.72 (m, 2H), 4.77 (dm, JHP
=
368.6 Hz, 2H); 13C NMR (75.4 MHz, CDCl3) δ 16.0, 16.1, 20.7,
21.9, 23.14, 23.16, 26.0 (d, JCP = 26.7 Hz), 26.5–26,6 (m), 27.1
(d, JCP = 32.3 Hz), 31.3–31.4 (m), 34.0, 40.5– 40.6 (m), 46.7–
46.8 (m), 76.1, 76.2, 167.2– 167.4 (m); 31P NMR (121.5 MHz, 1H
decoupled, CDCl3 ) δ 18.8–20.4 (m); IR (KBr) 2956, 2870, 2393,
1725, 1462, 1370, 1288 cm−1; HRMS EI m/z 299.2308. Calcd for
C16H33BO2P (M+−H) 299.2312.
Bornyl [Boranato(t-butyl)phosphino]acetate (2k, Diastereo-
meric Mixture). This compound was prepared from 1 and
bornyl chloroacetate in 67% yield (25 mmol scale) and isolated as
1
a white pasty solid. Mp 110–112 °C; H NMR (300.4 MHz,
CDCl3) δ 0.53 (br q, JHB = 96.2 Hz, 6H), 0.86–0.87 (m, 6H), 0.88
(m, 6H), 0.90 (6H), 1.02–1.13 (2H), 1.21–1.30 (m, 18H), 1.20–
1.40 (m, 2H), 1.66–1.73 (m, 2H), 1.70–1.83 (m, 2H), 1.86–2.03
(m, 2H), 2.30–2.45 (m, 2H), 2.68–3.18 (m, 4H), 4.76 (dm, JHP
=
368.8 Hz, 2H), 4.84–4.97 (m, 2H); 13C NMR (75.4 MHz, CDCl3)
δ 13.5–13.8 (m), 18.8, 19.6, 25.5, 25.6, 27.1, 27.2, 27.9, 29.5 (d,
JCP = 28.6 Hz), 36.4–36.6 (m), 44.8, 47.9, 48.6–48.9 (m), 82.1–
82.2 (m), 168.0–168.1 (m); 31P NMR (121.5 MHz, 1H decoupled,

1364 Bull. Chem. Soc. Jpn., 75, No. 6 (2002)
Reactions of t-Butylphosphine–Borane
t-Butyl(dimethyl)phosphine–Borane (4a). This compound
was prepared from 1 and methyl iodide in 94% yield (10 mmol
scale). After workup, the crude product was filtered by a short
column on silica gel. The filtrate was concentrated on a rotary
evaporator to give virtually pure t-butyl(dimethyl)phosphine–bo-
rane as a white solid. Mp 165.0–166.0 °C; 1H NMR (300.4 MHz,
CDCl3) δ 0.45 (br q, JHB = 98.2 Hz, 3H), 1.16 (d, 3JHP = 13.8 Hz,
9H), 1.23 (d, 2JHP = 9.8 Hz, 6H); 13C NMR (75.4 MHz, CDCl3) δ
7.3 (d, JCP = 35.4 Hz), 24.7 (d, 2JCP = 2.5 Hz), 26.5 (d, JCP = 35.3
0.98–1.17 (m, 4H), 1.21–1.33 (m, 18H), 1.42–1.49 (m, 6H), 1.46–
1.56 (m, 4H), 1.65–1.77 (m, 4H), 1.86–2.07 (m, 4H), 4.84–4.97
(m, 2H) ; 13C NMR (75.4 MHz, CDCl3) δ 4.5 (d, JCP = 34.8 Hz),
4.7 (d, JCP = 34.8 Hz), 15.7, 15,9 20.7, 20.8, 21.9, 22.0, 22,9 23.1,
25.4–25.6 (m), 25.9, 26.1, 28.6 (d, JCP = 28.6 Hz), 28.7 (d, JCP
=
28.6 Hz), 31.4–31.5 (m), 33.9, 34.0, 40.6, 40.8, 46.7, 47.0, 77.2,
77,4 171.3, 172.3; 31P NMR (121.5 MHz, 1H decoupled, CDCl3 )
δ 40.4–42.4 (m); IR (KBr) 2957, 2871, 2402, 2343, 1702, 1459,
1370 cm−1; HRMS EI m/z 299.2281. Calcd for C16H33BP
(M+−H) 299.2312.
1
Hz); 31P NMR (121.5 MHz, H decoupled, CDCl3 ) δ 20.9 (br q,
JPB = 64.4 Hz); IR (KBr) 2971, 2869, 2369, 1474, 1366 cm−1
HRMS EI m/z 131.1138. Calcd for C6H17BP (M+−H) 131.1151.
;
(1S)-endo-2-Bornyl Chloroformate. To a stirred, cooled (0
°C) solution of triphosgene (15.1 g, 50.8 mmol) in toluene (150
mL) was slowly added a solution of (−)-borneol (23.1 g, 149
mmol) and quinoline (19.3 g, 149 mmol) in toluene (150 mL) for
1 h under argon atmosphere. After 1 h, the reaction mixture was
allowed to warm to 60 °C slowly and stirred for 3 h at this temper-
ature. The reaction mixture was filtered off to remove the quino-
line salt. The filtrate was concentrated and distilled under reduced
pressure to give (1S)-endo-2-bornyl chloroformate as a colorless
Dibutyl(t-butyl)phosphine–Borane (4b).
This compound
was prepared from 1 and butyl chloride in 88% yield (2 mmol
scale) and isolated as colorless oil. 1H NMR (300.4 MHz, CDCl3)
δ 0.37 (br q, JHB = 96.6 Hz, 3H), 0.93 (t, J = 7.2 Hz, 6H), 1.16 (d,
3JHP = 12.8 Hz, 9H), 1.3–1.7 (m, 12H); 13C NMR (75.4 MHz,
CDCl3) δ 13.6 , 20.4 (d, JCP = 20.4 Hz), 24.8 (d, 2JCP = 12.4 Hz),
25.8 (d), 25.9, 28.1 (d, JCP = 33.5 Hz); 31P NMR (121.5 MHz, 1H
decoupled, CDCl3 ) δ 30.3 (br q, JPB = 69.3 Hz); IR (KBr) 2957,
2378, 1464, 1365 cm−1; HRMS EI m/z 202.1837. Calcd for
C12H27P (M+−BH3) 202.1850.
1
liquid (28.1 g, 87% yield). Bp 54–55 °C/0.2 mmHg; H NMR
(300.4 MHz, CDCl3) δ 0.86 (6H), 0.87 (3H), 1.11–1.19 (m, 1H),
1.20–1.40 (m, 2H), 1.66–1.80 (m, 2H), 1.80–1.94 (m, 1H), 2.30–
2.44 (m, 1H), 4.95 (dm, 1H); 13C NMR (75.45 MHz, CDCl3) δ
18.7, 19.6, 26.7, 27.8, 36.0, 44.6, 48.0, 49.3, 89.3, 150.6; IR (KBr)
2958, 1777, 1171, 1151 cm−1; HRMS EI m/z 216.0899. Calcd for
C11H17ClO2 (M+) 216.0917.
t-Butyl(ditetradecyl)phosphine–Borane (4c).
This com-
pound was prepared from 1 and tetradecyl chloride in 97% yield
(2 mmol scale) and isolated as white pasty oil. 1H NMR (300.4
MHz, CDCl3) δ 0.74 (br q, JHB = 114 Hz, 3H), 0.85 (t, J = 7.0
Hz, 6H), 1.12 (d, 3JHP = 12.9 Hz, 9H), 1.2–1.4 (m, 44H), 1.4–1.6
[(1S)-endo-2-Bornyloxycarbonyl](t-butyl)methylphosphine–
(m, 8H); 13C NMR (75.4 MHz, CDCl3) δ 14.1 , 20.6 (d, JCP
=
Borane (6, Diastereomeric Mixture).
To a stirred, cooled
2
31.0 Hz), 22.7, 23.8, 25.7, 28.1 (d, JCP = 32.9 Hz), 29.0–29.9
(−78 °C) solution of t-butyl(methyl)phosphine–borane (3.76 g, 31
mmol) in THF (80 mL) was slowly added n-BuLi (23 mL of 1.50
M hexane solution, 34 mmol) under argon atmosphere. After 30
min, (1S)-endo-2-bornyl chloroformate (7.1 g, 33 mmol, 1.05
equivalent) in THF (25 mL) was slowly added at −78 °C and the
mixture was stirred for 1 h. The mixture was allowed to warm to
room temperature and stirred for 3 h. Iced water containing HCl
was carefully added. The organic layer was separated and the
aqueous layer was extracted with ethyl acetate three times. The
combined extracts were washed with water and brine, dried
(Na2SO4), and concentrated. The residue was purified by flash
chromatography on silica gel eluting with hexane/ethyl acetate to
give a 1:1 diastereomeric mixture of bornyloxycarbonyl(t-bu-
tyl)methylphosphine–borane as a white solid (6.49 g, 70% yield).
This compound was also obtained from one pot treatment of t-bu-
tylphosphine–borane in 64% yield. Mp 50–65 °C; 1H NMR
(300.4 MHz, CDCl3) δ 0.60 (br q, JHB = 88.6 Hz, 6H), 0.87 (3H),
0.874 (3H), 0.90 (6H), 0.91 (6H), 1.0–1.1 (m, 2H), 1.22–1.33 (m,
18H), 1.22–1.44 (m, 4H), 1.47 (d, 2JHP = 9.6 Hz, 6H), 1.70–1.86
(m, 4H), 1.93–2.20 (m, 2H), 5.0–5.17 (m, 2H); 13C NMR (75.4
MHz, CDCl3) δ 4.5 (d, JCP = 35.4 Hz), 13.3, 13.6, 18.8, 19.6, 25.5
(m), 27.1, 27.8, 27.9, 28.6 (d, JCP = 28.4 Hz), 28.7 (d, JCP = 28.4
1
(m), 31.6–31.8 (m), 31.9; 31P NMR (121.5 MHz, H decoupled,
CDCl3 ) δ 30.3 (m, JPB = 69 Hz); IR (KBr) 2925, 2853, 2377,
1465, 1367 cm−1; HRMS EI m/z 489.4970. Calcd for C32H67P
(M+−BH3) 482.4980.
Dibenzyl(t-butyl)phosphine–Borane (4d). This compound
was prepared from 1 and benzyl chloride in 99% yield (2 mmol
1
scale) and isolated as white needles. Mp 147.2–148.0 °C; H
NMR (300.4 MHz, CDCl3) δ 0.59 (br q, JHB = 104.4 Hz, 3H),
1.12 (d, 3JPH = 13.5 Hz, 9H), 2.8–3.1 (m, 4H), 7.2–7.3 (m, 10H);
13C NMR (75.4 MHz, CDCl3) δ 14.1 , 25.7 (d), 28.9 (d, JCP
=
27.3), 29.5 (d, JCP = 28.0), 126.8–126.9 (m), 128.2–128.3 (m),
130.1–130.2 (m), 133.0–133.1 (m); 31P NMR (121.5 MHz, 1H de-
coupled, CDCl3 ) δ 33.1–34.8 (m); IR (KBr) 3030, 2979, 2394,
1455, 1366 cm−1; HRMS EI m/z 284.1837. Calcd for C18H26BP
(M+) 284.1865.
Derivation of t-Butyl(methyl)phosphine–Borane. t-Butyl-
(menthyloxycarbonyl)methylphosphine–Borane (5, Diastereo-
meric Mixture). To a stirred, cooled (−78 °C) solution of t-bu-
tyl(methyl)phosphine–borane (236 mg, 2 mmol) in THF (2 mL)
was slowly added n-BuLi (1.3 mL of 1.50 M hexane solution, 2
mmol) under argon atmosphere. After 10 min, (+)-menthyl chlo-
roformate (481 mg, 2.2 mmol) was slowly added at −78 °C. The
solution was stirred for 1 h and then allowed to warm to room
temperature. Iced water containing HCl was carefully added. The
organic layer was separated and the aqueous layer was extracted
with ethyl acetate three times. The combined extracts were
washed with water and brine, dried (Na2SO4), and concentrated.
The residue was purified by flash chromatography on silica gel
eluting with hexane/ethyl acetate. The eluent was concentrated to
give a 1:1 diastereomeric mixture of t-butyl(methyloxycarbon-
yl)methylphosphine–borane as colorless pasty oil (412 mg, 67%
Hz ), 36.7, 36.8, 44.7, 44.8, 48.9, 49.2, 82.8, 83.3, 172.3 (d, JCP
=
70.0 Hz), 172.4 (d, JCP = 69.5 Hz); 31P NMR (121.5 MHz, 1H de-
coupled, CDCl3 ) δ 40.8–43.0 (m); IR (KBr) 2956, 2880, 2378,
1704, 1475, 1368 cm−1; HRMS EI m/z 297.2155. Calcd for
C16H31BP (M+−H) 297.2155.
(RP)-[(1S)-endo-2-Bornyloxycarbonyl](t-butyl)methylphos-
phine–Borane (6a, 95% de). A solution of bornyloxycarbon-
yl(t-butyl)methylphosphine–borane (9.96 g, 33.4 mmol) in hexane
(60 mL) was allowed to warm to 60 °C. The mixture was slowly
cooled to 0 °C and stirred at this temperature for 3 h. The mixture
was filtered and the residue recrystallized from hexane. The col-
lected filtrates were concentrated and recrystallized 3 times. The
1
yield). H NMR (300.4 MHz, CDCl3) δ 0.56 (br q, JHB = 85.0 Hz,
6H), 0.74–0.77 (m, 6H), 0.8–0.9 (m, 2H), 0.89–0.97 (m, 12H),

N. Oohara et al.
Bull. Chem. Soc. Jpn., 75, No. 6 (2002) 1365
diastereomeric excess value of the obtained crystalline solid (3.2
Stephan, J. A. Laffitte, and J. P. Genêt, Tetrahedron Lett., 31, 6357
(1990). c) M. Ohff, J. Holz, M. Quirmbach, and A. Börner, Syn-
thesis, 1998, 1391. d) B. Carboni and L. Monnier, Tetrahedron
Lett., 55, 1197 (1999), and references cited therein.
1
g, 32%) was determined by H NMR analysis (95% de). Mp
97.6–99.0 °C; 1H NMR (300.4 MHz, CDCl3) δ 0.60 (br q, JHB
=
90.0 Hz, 3H), 0.87 (3H), 0.89 (3H), 0.90 (3H), 1.01–1.09 (m, 1H),
1.28 (d, 3JHP = 14.4 Hz, 9H), 1.27–1.43 (m, 2H), 1.47 (d, 2JHP
=
5
For representative reviews of preparation of alkylphos-
9.8 Hz, 3H), 1.69–1.86 (m, 2H), 1.93–2.01 (m, 2H), 2.33–2.50 (m,
phines, see “Organic Phosphorus Compunds,” ed by G. M.
Kosolapoff and L. Maier, John Wiley & Sons, New York (1972),
Vol. 1, Chapter 1.
2H), 5.00–5.09 (m, 1H); 13C NMR (75.4 MHz, CDCl3) δ 4.5 (d,
2
JCP = 35.1 Hz), 13.6, 18.8, 19.6, 25.5 (d, JCP = 1.9 Hz), 27.1,
27.8, 28.6 (d, JCP = 28.6 Hz), 36.8, 44.8, 48.0, 49.0, 83.4, 172.4
(d, JCP = 69.5 Hz); 31P NMR (121.5 MHz, 1H decoupled, CDCl3 )
δ 41.0–43.0 (m); IR (KBr) 2956, 2880, 2377, 1702, 1474, 1368
cm−1; HRMS EI m/z 297.2143. Calcd for C16H31BP (M+−H)
297.2155.
6
T. Nagata, S. Matsukawa, and T. Imamoto, J. Org. Chem.,
65, 4185 (2000)
7
T. Miura, H.Yamada, S. Kikuchi, and T. Imamoto, J. Org.
Chem., 65, 1877 (2000)
8
t-Butylphosphine is prepared on industrial scale by acid
(S)-t-Butyl(methyl)phosphine–Borane (95% ee).
To
a
catalyzed reaction of phosphine and isobutene, and it is mainly
used for as a phosphorus source in metalorganic chemical vapor
deposition (MOCVD) device.
stirred solution of 6a (596 mg, 2 mmol, 95% de) in CH3CN(10
mL)/CH3OH(3 mL) was added KOH (2.24 g, 40 mmol) in water
(6 mL) at room temperature. The mixture was vigorously stirred
until complete consuming of the starting material (TLC analysis,
ca. 4 h). The reaction mixture was treated with 1 M HCl, and ex-
tracted with Et2O. The aqueous layer was extracted with Et2O.
The combined extracts were washed with water and brine, dried
(Na2SO4), and concentrated at low pressure (20–30 mmHg). The
residue was purified by flash chromatography on silica gel eluting
with hexane/ethyl acetate to give (S)-t-butylmethylphosphine–bo-
rane as a colorless solid (177 mg, 75% yield, 95% ee). The abso-
lute configuration and ee value were determined by HPLC analy-
sis using Chiral Daicel AD-H column (10% 2-propanol/hexane, 1
mL/min) on the corresponding 2-pyridylmethyl derivative.6,7
[α]2D0 +3.4 (c 1.18, CHCl3); Other spectroscopic properties
were identical to those given for t-butylmethylphosphine–borane.
9
R. W. Rudolph and C. W. Schultz, J. Am. Chem. Soc., 93,
6821 (1971).
10 K. Bourumeau, A. C. Gaumont, and J. M. Denis, J. Orga-
nomet. Chem., 529, 205 (1997).
11 A. C. Gaumont, K. Bourumeau, J. M. Denis and P. Guenot,
J. Organomet. Chem., 484, 9 (1994).
12 a) D. C. Bradly, M. B. Hursthouse, M. Motevalli, and D. H.
Zheng, J. Chem. Soc., Chem. Commun., 1991, 7. b) H.
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Bissinger, and A. Z. Schier, Anorg. Allg. Chem., 619, 1519 (1993).
d) Y. Gourdel, P. Pellon, L. Toupet, and M. Le Corre, Tetrahedron
Lett., 35, 1197 (1994). e) T. Imamoto, E. Hirakawa, Y. Yamanoi,
T. Inoue, K. Yamaguchi, and H. Seki, J. Org. Chem., 60, 7697
(1995). f) T. Imamoto, T. Yoshizawa, K. Hirose, Y. Wada, H.
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(1995). g) A. Bader, M. Pabel, A. C. Willis, and S. B. Wild, Inorg.
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References
1
For representative reviews, see a) R. Noyori, “Asymmetric
Catalysis in Organic Synthesis,” John Wiley & Sons, New York
(1994). b) “Comprehensive Asymmetric Catalysis,” ed by E. N.
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“Catalytic Asymmetric Synthesis, 2nd ed,” ed by I. Ojima, VCH
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13 H. Dorn, R. A. Singh, J. A. Massey, A. J. Lough, and I.
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Jaska, A. J. Lough, and I. Manners, J. Am. Chem. Soc., 122, 6669
(2000).
2
For recent representative reports on chiral bisphosphines,
15 H. Dorn, E. Vejzovic, A. J. Lough, and I. Manners, Inorg.
Chem., 40, 4327 (2001).
16 A. R. Muci, K. R. Campos, and D. A. Evans, J. Am. Chem.
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17 B. Wolf and T. Livinghouse, J. Am. Chem. Soc., 120, 5116
(1998).
see a) P. J. Pye, K. Rossen, R. A. Reamer, N. N. Tsou, R. P.
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T. V. RajanBabu, T. A. Ayers, G. A. Halliday, K. K. You, and J. C.
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1100 (1998).
18 (1R, 2S, 5R)-menthyl chloroacetate and (1S)-endo-2-bornyl
chloroacetate were easily prepared from (−)-menthol and (−)-
borneol in 90% and 96% yields, respectively: K. Sisido, O. Naka-
nisi, and H. Nozaki, J. Org. Chem., 26, 4878 (1961).
19 Although separation of these diastereomers by recrystalli-
zation failed, other separation methods are still under investiga-
tion.
3
a) T. Imamoto, J. Watanabe, Y. Wada, H. Masuda, H.
Yamada, H. Tsuruta, S. Matsukawa, and K.Yamaguchi, J. Am.
Chem. Soc., 120, 1635 (1998). b) Y. Yamanoi and T. Imamoto, J.
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T. Huang, and T. Imamoto, Tetrahedron Lett., 40, 2577 (1999). d)
M. J. Burk, “Handbook of Chiral Chemicals,” ed by D. J. Ager,
Marcel Dekker, New York (1999), Chapter 18 and references
therein.
20 Determined by 1H NMR analysis.
21 We attempted to isolate another diastereomer (6b) by re-
crystallization. Unfortunately, the evaporation of the filtrate af-
forded a pasty oil that contained two diastereomers in a 24:76
(6a:6b) ratio.
4
a) T. Imamoto, T. Oshiki, T. Onozawa, T. Kusumoto, and
K. Sato, J. Am. Chem. Soc., 112, 5244 (1990). b) S. Jugé, M.