Chemo-, regio- and stereoselective conversion of P-chirogenic phosphorus borane complexes into their P=O or P=S derivatives

Article abstract of DOI:10.1016/S0957-4166(01)00236-1

Chiral and achiral organophosphorus borane complexes are readily transformed into their corresponding phosphoryl or thiophosphoryl compounds in high yields using one-pot procedures with stereoselectivities reaching 100% in many cases. Both oxidation and sulfuration were performed under neutral or mild conditions and were applied to various organophosphorus borane complexes (phosphines, phosphinates, chlorophosphines, aminophosphines, etc.). In the case of the dissymmetric diphosphine or aminophosphine phosphinite ligands, the reaction of their diborane complexes proceeds regiospecifically to a single phosphorus group, affording the corresponding hybrid derivatives.

Full text of DOI:10.1016/S0957-4166(01)00236-1

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 12 (2001) 1441–1449
Chemo-, regio- and stereoselective conversion of P-chirogenic
phosphorus borane complexes into their PꢀO or PꢀS derivatives
Jacques Uziel, Christophe Darcel, Dominique Moulin, Christophe Bauduin and Sylvain Juge´*
Unite´ mixte Universite´ de Cergy-Pontoise/ESCOM, Synth. Org. Se´lect. et Chim. Organome´tal., FRE CNRS 2126,
5 mail Gay Lussac, 95031 Cergy-Pontoise Cedex, France
Received 27 April 2001; accepted 23 May 2001
Abstract—Chiral and achiral organophosphorus borane complexes are readily transformed into their corresponding phosphoryl
or thiophosphoryl compounds in high yields using one-pot procedures with stereoselectivities reaching 100% in many cases. Both
oxidation and sulfuration were performed under neutral or mild conditions and were applied to various organophosphorus borane
complexes (phosphines, phosphinates, chlorophosphines, aminophosphines, etc.). In the case of the dissymmetric diphosphine or
aminophosphine phosphinite ligands, the reaction of their diborane complexes proceeds regiospecifically to a single phosphorus
group, affording the corresponding hybrid derivatives. © 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
would avoid the use of trivalent phosphorus com-
pounds which are often difficult to purify.
Introducing chirality at the phosphorus center of a
phosphoryl compound is of particular importance in
organophosphate agrochemistry,1 the development of
modified oligonucleotides2 and in the synthesis of phos-
phamide anti-tumor agents.3 The synthetic utility of
P(IV)-chirogenic compounds has also been demon-
strated using them as chiral auxiliaries,4 ligands5 or
catalysts6 in various asymmetric reactions, or as NMR
derivatizing shift reagents.7 Many of these compounds,
which are obtained by condensation of a chlorophos-
phoryl reagent with a chiral amino alcohol or diamine,
bear the chirality both at the phosphorus atom and at
the carbon backbone. Nevertheless, chiral phosphoryl
compounds can be prepared using racemate resolution
processes or asymmetric synthesis,8 but these methods
generally require several steps and are not very
versatile.
In connection with our continued work on chiral ligand
chemistry,10 we have investigated both oxidation and
sulfuration of organophosphorus borane complexes in
order to prepare the corresponding (thio)phosphoryl
derivatives. To date, the only direct use of organophos-
phorus borane complexes has been described by
Imamoto et al.,18 for a ‘one-pot’ synthesis of chiral or
achiral phosphine oxides and phosphinates, using an
excess of m-CPBA. However, these conditions are inap-
propriate for acid sensitive compounds such as
aminophosphine boranes and for the preparation of
hybrid ligands from diphosphine diboranes. We report
herein alternative neutral or milder ‘one-pot’ decom-
plexation/oxidation (or sulfuration) procedures, allow-
ing the chemo-, regio- and stereoselective synthesis of
various organophosphorus P-oxides 2 (or P-sulfides 3),
from the borane complexes 1 (Scheme 1).
Recently, significant advances have been made in the
asymmetric synthesis of P(III)-chirogenic phosphorus
compounds, owing to the use of borane protecting
groups.9–13 Although decomplexation of organophos-
phorus borane complexes can be achieved in some cases
with amines,14 olefins,15 EtOH10g or acids,16 direct use
of the complexes themselves in organic or organometal-
lic synthesis would be of great interest,17 since this
2. Results and discussion
Refluxing triphenylphosphine borane complex 1a or
dppe diborane 1b in a mixture of tert-butyl hydroper-
oxide and butanone at 80°C (method A) led to the
corresponding mono- and diphosphine oxides 2a and
2b in 94 and 85% isolated yields, respectively (Table 1,
entries 1, 2).
* Corresponding author. Fax: 33 1 34 25 70 67; e-mail: sylvain.juge
@chim.u-cergy.fr
0957-4166/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(01)00236-1

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J. Uziel et al. / Tetrahedron: Asymmetry 12 (2001) 1441–1449
Scheme 1.
Table 1. Oxidation of organophosphorus borane complexes into their corresponding phosphoryl derivatives
Thus, refluxing the triphenylphosphine borane complex
Under the same conditions, (S)-(+)-Pamp-BH3 1c led to
the corresponding (R)-(+)-Pampo 2c in 90% yield, with
significant retention of the configuration at the phospho-
rus center (91% e.e.; entry 3). However, 2c was obtained
stereospecifically when the Pamp-BH3 1c was decom-
plexed by DABCO at 40°C, then oxidized using tert-
BuOOH (method B; entry 3). In the case of the
phosphinite borane (R)-1d, the oxidation method A gave
the phosphinate (R)-2d with moderate stereoselectivity
(45% e.e.), but when the decomplexation step was carried
out with DABCO at 40°C (method B), the e.e. was 82%
(entry 4). It should be pointed out that few publications
mention the preparation of P-chirogenic acyclic phos-
phinites and, to our knowledge, their configurational
stability seems to be lower than that of the phosphines.19
Under the conditions in method B, the oxazaphospho-
lidine and aminophosphine borane complexes 1e and 1f
gave the corresponding diastereomerically pure com-
pounds 2e and 2f isolated in good yields (entries 5, 6).
1a or dppe diborane 1b, in a mixture of THF/1-octene
(2:1) and S8 (method C), led to the corresponding mono-
and diphosphine sulfides 3a and 3b in 90 and 88% isolated
yields, respectively (Table 2, entries 1, 2). Under the same
sulfuration conditions, (R)-(−)-Pamp-BH3 1c gave (S)-
(−)-Pamp-sulfide 3c in 80% yield with complete retention
of configuration at the phosphorus atom (entry 3). In the
case of the sulfuration of the phosphinite borane (R)-1d,
the thiophosphinite (S)-3d was obtained in 98% yield,
and the analysis of the (R)-Pamp sulfide 3c resulting from
the reaction of 3d with methyllithium indicated an e.e.
of 90% (entry 4). Similarly, the oxazaphospholidine
borane complex 1e and the aminophosphine borane 1g
afforded the corresponding sulfides 3e and 3g with
diastereoselectivities of 88 and 100%, respectively (entries
5, 6). However, a stereoselectivity >94% was obtained for
3e by heating 1e carefully in toluene at 40°C with a
mixture of DABCO and sulfur (method D; entry 5).
Interestingly, sulfuration of the chlorophosphine borane
(S)-1h10g gave the thiophosphoryl derivative 3h in good
yield (entry 7). Unfortunately, compound 3h was
obtained as a racemic mixture, in spite of the neutral and
In addition, the one-pot sulfuration of borane complexes
1 has also been investigated to prepare P-chirogenic
thiophosphoryl compounds (Table 2).

J. Uziel et al. / Tetrahedron: Asymmetry 12 (2001) 1441–1449
1443
Table 2. Sulfuration of organophosphorus borane complexes into their corresponding thiophosphoryl derivatives
mild decomplexation conditions in 1-octene at 40°C;
this is probably due to the weak configurational stabil-
ity of the P(III) chlorophosphine intermediate.20
phinite borane 3k was obtained diastereospecifically
from the AMPP diborane complex 1k,10f according to a
regio- and stereoselective sulfuration of the aminophos-
phine functionality (entry 4).
The chemoselectivity of both oxidation and sulfuration
reactions was next investigated, in order to prepare
hybrid (thio)phosphoryl compounds, starting from dis-
symmetric diborane phosphorus complexes (Table 3).
Thus, when a mixture of triphenylphosphine and tri-
ethylphosphite borane complexes 1a and 1i (1:1) was
treated with sulfur (method C), triphenylphosphine
sulfide 3a was obtained as a single product after reflux-
ing in THF for 3 hours, while 1i remained unchanged
(entry 1). Under the reaction conditions of method B,
the Josiphos21 diborane complex 1j afforded the phos-
phine oxide borane complex 2j in 90% yield (entry 2),
by regiospecific oxidation of the arylphosphino borane
group. It should be pointed out that, on m-CPBA
oxidation,18 1j afforded a mixture of mono- and
diphosphine oxide derivatives. Finally, the Josiphos
diborane complex 1j led regiospecifically to the phos-
phine sulfide borane complex 3j under the sulfuration
conditions of method C (entry 3).
3. Conclusions
In summary, we have described chemo-, regio- and
stereoselective methods affording phosphoryl or thio-
phosphoryl compounds in high yields either by direct
oxidation or sulfuration of organophosphorus borane
complexes. The mild and neutral conditions used were
applied to various kinds of organophosphorus borane
complexes, including chlorophosphines, aminophos-
phines and acid sensitive compounds. We have shown
that both oxidation and sulfuration of P-chirogenic
borane complexes proceeds with retention of configura-
tion at the P-center and with stereoselectivities from 82
to 100% (excepting the chlorophosphine which gave a
racemic thiophosphoryl derivative). These methods
offer an alternative route to homochiral (thio)-
phosphoryl compounds from phosphine borane com-
plexes, which can be used in these reactions as easily
handled and stable P(III) precursors.
Finally, the P-chirogenic thiophosphinamide phos-

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J. Uziel et al. / Tetrahedron: Asymmetry 12 (2001) 1441–1449
Table 3. Preparation of hybrid (thio)phosphoryl compounds from the organophosphorus diborane complexes
4. Experimental
4.2. Preparation of the organophosphorus boranes 1
The triphenylphosphine borane 1a, the 1,2-bis-
(diphenylphosphino)ethane diborane 1b and the tri-
ethylphosphite borane 1i were prepared as described,
from the corresponding P(III)-organophosphorus
derivatives and borane dimethylsulfide in THF, then
purified by recrystallization in cyclohexane or toluene
for 1a and 1b or by distillation in the case of 1i.
4.1. General
All reactions were carried out under an argon or a
nitrogen atmosphere in dried glassware. THF and tolu-
ene were dried and freshly distilled under a nitrogen
atmosphere over sodium/benzophenone. Hexane and
ethanol for HPLC were of chromatographic grade and
were used without further purification. n-Butyllithium,
1a: mp=189°C, lit.22 mp=189°C; 1b: mp=166–8°C,
lit.22b mp=162–167°C; 1i: bp=64°C (1 mmHg); 1H
NMR (CDCl3) (lit.23) l ppm, J Hz: 4.06 (6H, qt,
2-bromoanisole,
1-octene,
t-butylhydroperoxide,
BH3·S(CH3)2 and DABCO were purchased from
Aldrich, Acros and Avocado. Commercially available
2-bromoanisole was distilled before use. HPLC analyses
were performed on a Gilson 305/306 chromatograph
equipped with a UV 116 detector. Flash chromatogra-
phy was performed on silica gel (60AC.C, 35–70 mm;
SDS) or neutral aluminum oxide (Carlo Erba; ref.
417241). All NMR spectral data were obtained on a
Bruker DPX 250 spectrometer using TMS as internal
3
4
3JHH=3JPH=7, OCH2), 1.31 (9H, dt, JHH=7, JPH=1,
CH3), 0.41 (3H, qd, 1JBH=97, 2JPH2=18, BH3); 13C
NMR (CDCl3) l ppm, J Hz: 62.5 (d, JPOC=4, OCH2),
3
16.2 (d, JPOCC=6, CH3); 31P NMR (CDCl3) l ppm:
1
+114.4 (q, JPB=102).
The (R)-(−)-o-anisyl methylphenylphosphinite borane
reference for H (250 MHz) and 13C NMR (62.9 MHz)
1
1c,
(2S,4R,5S)-(−)-3,4-dimethyl-2,5-diphenyl-1,3,2-
and 85% phosphoric acid as external reference for 31P
NMR (101.3 MHz). Melting points were measured on a
Bu¨chi melting point apparatus and are uncorrected.
Optical rotation values were determined at 20°C on a
Perkin–Elmer 241 polarimeter. Infrared spectra were
recorded on a Bruker Equinox 55. Mass spectral analy-
ses were performed on a JEOL MS 700 at the Mass
Spectroscopy Laboratories of ENS Paris. Elemental
analyses were measured with a precision greater than
0.4% at the Microanalysis Laboratories of P. & M.
Curie University (Paris).
oxazaphospholidine borane 1e, (Sp)-(+)-N-methyl-N-
[(1S,2R)-(1-hydroxy-2-methyl-1-phenyl-prop-2-yl)]ami-
nomethylphenylphosphine borane 1g, (R)-o-ani-
sylchlorophenylphosphine borane 1h10g and (Rp)-N-
methyl-N-{(1R,2S)-[2-(dicyclohexylphosphinitoborane)-
1-methyl-2-phenyl]ethyl}amino-o-anisylphenylphosphine
borane 1k10f complexes, were prepared from (+)-ephe-
drine according to the published procedure.10c,10f Like-
wise, the (S)-(+)-o-anisylmethylphenylphosphine borane
1c and (R)-(−)-[(O-methyl)-o-anisylphenylphosphinite]-
borane 1d were obtained starting from (−)-ephedrine.

J. Uziel et al. / Tetrahedron: Asymmetry 12 (2001) 1441–1449
1445
4.2.1.
(Rp)-(−)-N-Methyl-N-[(1S,2R)-(1-acetoxy-2-
HRMS (DCI, CH4) calcd for C36H49B2FeP2 [M−H+]:
methyl-1-phenyl-prop-2-yl)]amino-o-anisylphenylphos-
phine borane 1f. A 100 mL round-bottomed flask
equipped with a magnetic stirrer and an argon inlet was
charged with a solution of 2.85 g of the oxazaphospho-
lidine borane 1e (15 mmol) in THF (15 mL). o-Anisyl-
lithium reagent (1.5 equiv.) was added slowly at −78°C
under stirring, and the reaction mixture was slowly
warmed to 0°C until complex 1e had completely disap-
peared. The reaction was monitored by TLC over silica
(toluene/AcOEt 9:1). To this was added acetic anhy-
dride (16.5 mmol, 1.65 equiv.). After stirring for 2 h,
the mixture was warmed overnight to room tempera-
ture. The THF was removed under reduced pressure,
the residue was hydrolyzed at room temperature and
extracted with CH2Cl2. The combined extracts were
dried over MgSO4 and the solvent removed. The
residue was purified by chromatography on silica gel
using toluene, followed by a mixture of toluene/AcOEt
(9:1) as eluent, yielding complex 1f (2.85 g, 66% yield).
621.2845; found: 621.2842.
4.3. Oxidation of organophosphorus boranes
4.3.1. Typical procedures
4.3.1.1. Method A. A mixture of organophosphorus
borane complex (0.5 mmol), tert-BuOOH (0.2 mL; 2
mmol) and butanone (2 mL) was heated at 80°C and
the reaction was monitored by TLC. After between 6
and 24 h, the mixture was cooled to 0°C and was then
poured into a solution of FeSO4 (1.5 mL, 1.8 mmol)
and tartaric acid (0.9 mmol). After stirring for 10 min,
the mixture was extracted with CH2Cl2, and the organic
extracts were successively washed with NaOH (0.3 M)
and water and finally dried with MgSO4. The solvent
was removed and the residue was purified by chro-
matography on silica gel, using a mixture of cyclohex-
ane/AcOEt (4:1) as eluent.
4.3.1.2. Method B. A mixture of Josiphos diborane
complex (0.115 mmol), DABCO (0.115 mmol) and
toluene (2 mL) was heated under argon at 40°C for 11
h, to which t-BuOOH (0.52 mmol) was added at room
temperature. After 2 h, the solvent was removed and
the residue was purified by chromatography on silica
gel, using a mixture of cyclohexane/AcOEt (4:1) as
eluent.
White solid; mp 128–129°C; Rf=0.4 (toluene); [h]2D0=
−14.3 (c 1.5, CHCl3); 1H NMR (CDCl3) l ppm, J
Hz: 7.54–7.36 (4H, m, H arom.), 7.26–7.05 (6H, m, H
arom.), 6.98–6.79 (4H, m, H arom.), 5.76 (1H, d,
3JHH=8, PhCH), 4.45 (1H, m, MeCHN), 3.47 (3H, s,
CH3O), 2.38 (3H, d, 3JPH=8, NCH3), 1.99 (3H, s,
3
CH3CO), 1.17 (3H, d, JHH=7), 1.6–0.0 (3H, br, BH3);
13C NMR (CDCl3) l ppm, J Hz: 170.0 (C arom.), 161.0
(d, JPC=2, C arom.), 138.4 (C arom.), 135.1 (d, JPC
=
The triphenylphosphine oxide 2a and dppe dioxide 2b
exhibit satisfactory analytical data in agreement with
the literature. 2a: 31P NMR (CDCl3) l ppm: +29.3; lit.24
11, C arom.), 133.4–127.7 (C arom.), 122.7–112.3 (C
3
arom.), 111.5 (d, JPC=5, C arom.), 78.9 (d, JPNCC=7,
2
1
l ppm: +32; 2b: H NMR (lit.25).
PhCHO), 56.4 (d, JPNC=12, NCHMe), 55.0 (CH3O),
30.1 (d, 2JPNC=4, NCH3), 21.3 (CH3CO), 14.2
1
(CH3CH); 31P NMR (CDCl3) l ppm: +70.5 (m, JPB
=
4.3.2. o-Anisylmethylphenylphosphine oxide (Pampo)
2c26. Uncrystallized, colorless; 1H NMR (CDCl3) l
ppm, J Hz: 7.88 (1H, ddd, J=2, J=8, J=13, H arom.),
7.67 (2H, ddd, J=2, J=8, J=13, H arom.), 7.43–7.33
(4H, m, H arom.), 7.03 (1H, t, J=7, H arom.), 6.82
(1H, dd, J=5, J=8, H arom.), 3.65 (3H, s, CH3O),
69); HRMS (DCI, CH4) calcd for C25H30BNO3P [M−
H+]: 434.2057; found: 434.2053; Anal. calcd for
C25H31BNO3P (435.3): C, 68.98; H, 7.18; N, 3.22;
found: C, 68.85; H, 7.29; N, 3.28%.
2
2.00 (3H, d, JPH=14, CH3P); 13C NMR (CDCl3) l
4.2.2.
(R)-(−)-1-(Dicyclohexylphosphinoborane)-1-[2-
(diphenylphosphinoborane)ferrocenyl]ethane 1j. This dib-
orane complex was prepared by addition of
BH3·S(CH3)2 in a 0.5 M THF solution of the Josiphos
complex.21
ppm: 159.8 (d, JPC=4, C arom.), 135.5–133.7 (C
arom.), 131.2 (d, JPC=3, C arom.), 130.1 (d, JPC=10, C
arom.), 128.1 (d, JPC=12, C arom.), 121.1 (d, JPC=100,
C arom.), 120.9 (d, JPC=11, C arom.), 110.8 (d, JPC=7,
1
C arom.), 55.2 (CH3O), 16.0 (d, JPC=75, CH3P); 31P
Orange solid; mp 186–187°C; Rf=0.7 (cyclohexane/
AcOEt 4:1); [h]2D0=−129 (c 1, CHCl3); 1H NMR
(CDCl3) l ppm: 7.79–7.61 (4H, m, H arom.), 7.44–7.30
(6H, m, H arom.), 5.16 (1H, s, C5H3), 4.62 (1H, t,
NMR (CDCl3) l ppm: +30.1.
The enantiomeric excess of the Pampo 2c was deter-
mined by HPLC on a Chiralcel OD column (Daicel),
with a hexane/EtOH (98:2) mixture as eluent, flow rate
1 mL min−1 and UV detection u=254 nm: (R)-enan-
tiomer tR=50.6 min, (S)-enantiomer tR=55.3 min.
JPH=2.5, C5H3), 4.24 (5H, s, C5H5), 4.21 (1H, m,
C5H3), 3.66 (1H, qd, J=7, J=14, CHCH3), 1.94 (3H,
dd, J=7.2, J=13, CHCH3), 2.10–0.58 (28H, m, BH3,
C6H11); 13C NMR (CDCl3) l ppm, J Hz: 133.2 (d,
J=9.5, C arom.), 132.7 (d, J=9.5, C arom.), 131.6 (C
arom.), 130.9 (d, JPC=3, C arom.), 130.8 (d, JPC=3, C
arom.), 130.3 (d, JPC=31, C arom.), 128.6 (d, JPC=10,
4.3.3.
(R)-(−)-(O-Methyl)-o-anisylphenylphosphinate
2d27c. Uncrystallized, colorless; Rf=0.26 (cyclohexane/
acetone 6:4); [h]2D0=−10.5 (c 1, CHCl3), 45% e.e.; H
1
C arom.), 128.2 (d, JPC=10, C arom.), 98.7 (dd, JPC
=
NMR (CDCl3) l ppm, J Hz: 7.91 (1H, ddd, J=2, J=8,
J=13, H arom.), 7.78 (2H, ddd, J=2, J=8, J=13, H
arom.), 7.46–7.20 (4H, m, H arom.), 7.00 (1H, td, J=2,
J=7, H arom.), 6.80 (1H, dd, J=6, J=8, H arom.),
3.64 (3H, s, CH3O); 13C NMR (CDCl3) l ppm: 160.9
(d, JPC=4, C arom.), 134.7 (d, JPC=6, C arom.), 134.4
4, JPC=17, C arom.), 73.8 (dd, JPC=4, JPC=8, C5H3),
71.4 (d, JPC=3, C5H3), 70.5 (C5H5), 69.8 (d, JPC=6,
C5H3), 67.4 (dd, JPC=4, JPC=64, C5H3), 32.3 (d, JPC
=
2), 32.0, 28.2–25.6, 24.0, 22.4 (d, JPC=27); 31P NMR
(CDCl3) l ppm: +38.6 (m, PC6H11), +11.1 (m, PC6H5).

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J. Uziel et al. / Tetrahedron: Asymmetry 12 (2001) 1441–1449
(d, JPC=2, C arom.), 133.0 (C arom.), 131.8 (d, JPC=3,
C arom.), 131.7 (d, JPC=11, C arom.), 128.0 (d, JPC
14, C arom.), 120.6 (d, JPC=12, C arom.), 118.7 (d,
128.3 (d, JPC=12), 72.9 (C5H3), 71.0 (C5H3), 70.7
=
(C5H3), 70.3 (C5H5), 32.9 (d, JPC=28.4), 30.0 (d, JPC=
29), 27.5–25.6, 22.7, 22.5 (d, JPC=24); 31P NMR
(CDCl3) l ppm, J Hz: 38.3 (m), 26.7; HRMS (EI) calcd
for C36H47BFeOP2 [M+]: 624.2552; found: 624.2544.
J
PC=136, C arom.), 111.2 (d, JPC=8, C arom.), 55.5
2
(CH3O), 51.4 (d, JPC=6, CH3OP); 31P NMR (CDCl3)
l ppm: +32.5.
4.4. Sulfuration of organophosphorus boranes
4.4.1. Typical procedures
The enantiomeric excess of the phosphinate 2d was
determined by HPLC on a Chiralcel OD column
(Daicel), with a hexane/EtOH (98:2) mixture as eluent,
flow rate 1 mL min−1 and UV detection u=254 nm:
(S)-enantiomer tR=32.4 min, (R)-enantiomer tR=34.2
min.
4.4.1.1. Method C. A mixture of organophosphorus
borane complex (1 mmol), 1-octene (4 mmol) and THF
(3 mL) was refluxed in the presence of sulfur (4 mmol)
for 24 h. After cooling, the solvent was removed and
the residue was purified by chromatography on silica
gel, using a mixture of cyclohexane/AcOEt as eluent.
4.3.4. (2S,4R,5S)-(+)-3,4-Dimethyl-2,5-diphenyl-1,3,2-
oxazaphospholidine 2-oxide 2e27. White solid; mp 154–
155°C; Rf=0.25 (cyclohexane/AcOEt 1:1); [h]2D0=+26.2
(c 1, CHCl3); 1H NMR (CDCl3) l ppm, J Hz: 7.90 (2H,
ddd, J=2, J=8, J=13, H arom.), 7.60–7.20 (8H, m, H
arom.), 5.63 (1H, dd, J=5, J=6, PhCHO), 3.79 (1H,
qd, 3JHH=6, 3JPNCH=14, MeCHN), 2.64 (3H, d,
3JPNCH=10, CH3N), 0.92 (3H, d, 3JHH=7, CH3CH);
13C NMR (CDCl3) l ppm: 136.2 (d, JPC=5, C arom.),
4.4.1.2. Method D. The borane complex (0.115
mmol), DABCO (0.115 mmol) and toluene (2 mL) were
heated under argon at 40°C for 11 h in the presence of
sulfur (4 mmol), after which the reaction mixture was
treated as for method C.
2
132.3–126.2 (C arom.), 82.6 (d, JPOC=2, POCH), 59.2
(d, 2JPNC=10, PNCH), 28.6 (d, 2JPNC=6, PNCH3),
14.5 (d, 3JPNCC=2, CH3CH); 31P NMR (CDCl3) l
ppm: +34.
The triphenylphosphine sulfide 3a and dppe disulfide 3b
exhibit satisfactory analytical data in agreement with
the literature. 3a: 31P NMR (CDCl3) l ppm: +43; lit.24
+44. 3b: mp 223–225°C; 31P NMR (CDCl3) l ppm: +44;
lit.25 mp 224–225°C.
4.3.5.
(Sp)-(+)-N-Methyl-N-[(1S,2R)-(1-acetoxy-2-
methyl-1-phenyl-prop-2-yl)]amino-o-anisylphenylphos-
phine oxide 2f. Uncrystallized, colorless; Rf=0.5
(cyclohexane/AcOEt 1:1); [h]2D0=+1.5 (c 0.6, CHCl3);
1H NMR (CDCl3) l ppm, J Hz: 7.82 (1H, ddd, J=2,
J=8, J=13, H arom.), 7.51–7.19 (11H, m, H arom.),
7.00 (1H, td, J=1, J=7, H arom.), 6.88 (1H, dd, J=6,
4.4.2. (S)-(−)-o-Anisylmethylphenylphosphine sulfide
3c28. White solid; Rf=0.3 (cyclohexane/AcOEt 85:15);
1
[h]2D0=−7.9 (c 0.5, MeOH); H NMR (CDCl3) l ppm, J
Hz: 8.22 (1H, ddd, J=2, J=8, J=17, H arom.), 7.73
(2H, m, H arom.), 7.55–7.35 (4H, m, H arom.), 7.26–
7.09 (1H, m, H arom.), 6.87 (1H, dd, J=6, J=8, H
arom.), 3.65 (3H, s, CH3O), 2.36 (3H, d, 2JPH=14,
CH3P); 13C NMR (CDCl3) l ppm, J Hz: 159.8 (d,
3
J=8, H arom.), 5.92 (1H, d, JHH=7, PhCHO), 4.12
3
3
(1H, qd, JHH=7, JPH=10, NCHCH3), 3.70 (3H, s,
CH3O), 2.52 (3H, d, 3JPH=11, CH3N), 2.06 (3H, s,
CH3CO), 1.25 (3H, d, 3JHH=7, CH3CH); 13C NMR
(CDCl3) l ppm: 170.0 (CH3CO), 160.4 (d, JPC=3, C
arom.), 138.5 (C arom.), 135.8 (d, JPC=7, C arom.),
133.8 (C arom.), 132.5 (d, JPC=134, C arom.), 132.0 (d,
J
PC=2.5, C arom.), 135.5 (d, JPC=10, C arom.), 135.3
(d, JPC=86, C arom.), 134.0 (d, JPC=2, C arom.), 130.7
(d, JPC=3, C arom.), 129.9 (d, JPC=11, C arom.), 128.1
(d, JPC=13, C arom.), 120.9 (d, JPC=13, C arom.),
119.9 (d, JPC=80, C arom.), 111.0 (d, JPC=6, C arom.),
55.3 (CH3O), 20.7 (d, JPC=61, CH3P); 31P NMR
(CDCl3) l ppm: +36.5.
J
PC=11, C arom.), 131.2 (d, JPC=3, C arom.), 128.2–
127.2 (C arom.), 120.7 (d, JPC=12, C arom.), 118.7 (C
arom.), 110.7 (d, JPC=7, C arom.), 78.7 (d, JPC=6,
2
2
PhC HO), 55.0 (CH3O), 53.2 (d, JPC=4, NCH), 28.7
(d, JPC=5, NCH3), 21.2 (CH3CO), 13.8 (CH3CH); 31P
2
NMR (CDCl3) l ppm: +32; HRMS (DCI, CH4) calcd
4.4.3. (S)-(−)-(O-Methyl)-o-anisylphenylthiophosphinate
3d. Yellow oil; Rf=0.25 (toluene); [h]2D0=−42.5 (c 1.4,
for C25H29NO4P [M+H+]: 438.1834; found: 438.1830.
1
CHCl3), 90% e.e.; H NMR (CDCl3) l ppm, J Hz: 8.02
4.3.6. (R)-(−)-1-(Dicyclohexylphosphino borane)-1-[2-
(diphenylphosphino oxide)ferrocenyl]ethane 2j. Orange
solid; mp 250–251°C; [h]2D0=−127.5 (c 0.5, CHCl3); IR
(KBr, w cm−1): 2935, 2919, 2374, 2355, 2338, 2336, 1437,
(1H, ddd, J=2, J=8, J=16, H arom.), 7.79 (2H, ddd,
J=2, J=8, J=14, H arom.), 7.40–7.30 (4H, m, H
arom.), 7.20–6.97 (2H, m, H arom.), 6.76 (1H, dd,
3
J=7, J=8, H arom.), 3.61 (3H, d, JPH=14, CH3OP),
1
1189, 1163, 1112, 754, 719, 705, 699; H NMR (CDCl3)
3.52 (3H, s, CH3O); 13C NMR (CDCl3) l ppm, J Hz:
160.7 (d, JPC=4, C arom.), 135.2 (d, JPC=114, C
arom.), 135.1 (d, JPC=9, C arom.), 134.7 (d, JPC=2, C
arom.), 131.8 (d, JPC=3, C arom.), 131.5 (d, JPC=12, C
arom.), 129.0 (d, JPC=51, C arom.), 128.3 (d, JPC=14,
C arom.), 125.7 (C arom.), 121.9 (d, JPC=110, C
arom.), 121.0 (d, JPC=13, C arom.), 112.1 (d, JPC=7, C
arom.), 56 (CH3O), 51.5 (d, JPC=6, CH3P); 31P NMR
(CDCl3) l ppm: +82.2.
l ppm, J Hz: 7.90–7.77 (4H, m, H arom.), 7.48–7.38
(6H, m, H arom.), 4.80 (1H, s, C5H3), 4.40 (1H, dd,
J=2, J=5, C5H3), 4.23 (1H, s, C5H3), 3.97 (5H, s,
C5H5), 3.81 (1H, m, CHCH3), 1.81 (1H, m), 1.70 (3H,
3
3
dd, JHH=7, JPH=14, CH3), 1.7–0.4 (24H, m, C6H11);
13C NMR (CDCl3) l ppm, J Hz: 136.1 (d, JPC=14),
134.5 (d, JPC=17), 131.4 (d, JPC=2), 131.3 (d, JPC=2),
131.2 (d, JPC=9), 130.8 (d, JPC=9), 128.5 (d, JPC=12),

J. Uziel et al. / Tetrahedron: Asymmetry 12 (2001) 1441–1449
1447
4.4.4. (2R,4R,5S)-(−)-3,4-Dimethyl-2,5-diphenyl-1,3,2-
oxazaphospholidine 2-sulfide 3e27d. Major isomer: white
solid; mp 84°C; Rf=0.35 (toluene/AcOEt 7:3); [h]2D0=
−21.1 (c 1, CHCl3); 1H NMR (CDCl3) l ppm, J Hz: 7.90
(2H, ddd, J=2, J=8, J=13, H arom.), 7.60–7.20 (8H,
m, H arom.), 5.58 (1H, dd, J=4, J=6, PhCHO), 3.72
CpCH), 1.75 (3H, dd, J=7, J=13, CH3CH), 1.7–0.6
(25H, m, C6H11); 13C NMR (CDCl3) l ppm, J Hz:
134.8 (d, JPC=42, C arom.), 133.4 (d, JPC=44, C
arom.), 132.6 (d, JPC=11, C arom.), 132.5 (d, JPC=12,
C arom.), 131.7 (C arom.), 131.6 (C arom.), 128.8 (d,
JPC=12, C arom.), 128.4 (d, JPC=12, C arom.), 74.8
3
(1H, m, MeCHN), 2.57 (3H, d, JPNCH=12, CH3N),
(C5H3), 72.9 (d, JPC=12, C5H3), 71.8 (C5H3), 71.1
(C5H5), 69.1 (d, JPC=11, C5H3), 32.3 (d, J=29), 32.2
(d, JPC=30), 28.3–26.1, 23.8, 22.6 (d, JPC=26); 31P
NMR (CDCl3) l ppm: +40.2, +38.5 (m); HRMS (FAB)
calcd for C36H46BFeP2S [M+−H]: 639.2245; found:
639.2233; anal. calcd for C36H47BFeP2S (640): C, 67.50;
H, 7.34; found: C, 67.27; H, 7.34.
3
0.85 (3H, d, JHH=7, CH3CH); 13C NMR (CDCl3) l
ppm: 136.1 (d, JPC=6, C arom.), 134.8 (d, JPC=128, C
arom.), 132.1 (d, JPC=3, C arom.), 131.1 (d, JPC=12, C
arom.), 128.5–126.4 (C arom.), 83.5 (d, 2JPOC=4,
2
2
POCH), 60.0 (d, JPNC=8, PNCH), 29.2 (d, JPNC=6,
PNCH3), 13.5 (d, 3JPNCC=3, CH3CH); 31P NMR
(CDCl3)
l ppm: +94.5; HRMS (EI) calcd for
C16H18NOPS [M+]: 303.0847; found: 303.0846.
4.4.8. (Sp)-(−)-N-Methyl-N-{(1R,2S)-[1-(dicyclohexyl-
phosphinito
borane)-1-phenyl]prop-2-yl}amino-o-anisyl
Minor isomer (2S,4R,5S): Rf=0.30 (toluene/AcOEt
phenylphosphine sulfide 3k. White solid; mp 152–153°C;
Rf=0.7 (cyclohexane/AcOEt 8:2); [h]2D0=−16.2 (c 1,
CHCl3); 1H NMR (CDCl3): l 7.8–6.8 (14H, m, H
arom.), 5.15 (1H, t, J=9, PhCHO), 4.93 (1H, m,
1
7:3); H NMR (CDCl3) l ppm, J Hz: 7.97 (2H, ddd,
J=2, J=8, J=15, H arom.), 7.52–7.19 (8H, m, H
arom.), 5.85 (1H, d, J=7, PhCHO), 3.70 (1H, m,
3
3
MeCHN), 2.69 (3H, d, JPNCH=12, CH3N), 0.77 (3H,
CHMe), 3.60 (3H, s, CH3O), 2.47 (3H, d, JPH=12,
3
2
d, JHH=7, CH3CH); 31P NMR (CDCl3) l ppm: +95.8.
NCH3), 1.40 (3H, d, JPH=7, PCH3), 2.1–0.6 (25H, m);
13C NMR (CDCl3) l ppm, J Hz: 160.3 (C arom.), 139.5
(C arom.), 135.8–127.5 (C arom.), 122.0–120.3 (C
arom.), 111.5 (d, JPC=7, C arom.), 111.0 (C arom.),
82.4 (d, 2JPC=5, PhCHO), 55.1 (CH3O), 54.2 (dd,
2J=6, 3J=14, NCH), 37.6–14.1 (CH3CH, NCH3,
C6H11); 31P NMR (CDCl3) l ppm, J Hz: +135.8 (m),
+68.1; MS (EI) m/z (relative intensity): 622 (M++H; 5),
394 (10), 362 (10), 305 (30), 304 (100), 247 (100), 215
(30), 183 (10), 91 (20); HRMS (DCI, CH4) calcd for
C35H51BNO2P2S [M++H]: 622.3209; found: 622.3222.
4.4.5. (Rp) - (−) - N - Methyl - N - [(1R,2S) - 1 - hydroxy - 1-
phenyl - prop - 2 - yl]aminomethylphenyl - phosphine sulfide
3g29. White solid; mp 126–127°C; Rf=0.5 (toluene/
AcOEt 8:2); [h]D20=−1.4 (c 0.5, CHCl3); 1H NMR
(CDCl3) l ppm, J Hz: 7.59 (2H, m, H arom.), 7.46–7.09
(8H, m, H arom.), 4.75 (1H, d, J=5, PhCHO), 3.84
3
(1H, m, MeCHN), 2.46 (3H, d, JPNCH=13, CH3N),
2
3
1.90 (3H, d, JPCH=13, CH3P), 1.12 (3H, d, JHH=7,
CH3CH); 13C NMR (CDCl3) l ppm: 142.2 (C arom.),
134.1 (d, JPC=102, C arom.), 131.4 (d, JPC=3, C
arom.), 130.8 (d, JPC=11, C arom.), 128.4 (d, JPC=13,
C arom.), 128.2–126.2 (C arom.), 77.6 (POCH), 56.3 (d,
Acknowledgements
2
2JPNC=3, PNCH), 29.2 (d, JPNC=3, PNCH3), 21.4 (d,
1JPC=73, PC H3), 12.4 (d, 3JPNCC=2, CH3CH); 31P
NMR (CDCl3) l ppm: +66.7; HRMS (EI) calcd for
C17H23NOPS [M+H+]: 320.1238; found: 320.1237.
We thank Dr. B. Pugin and Solvias A.G. for their gift
of Josiphos. This research was supported by the Min-
istry of Research (Fund and Fellowship for C.B.) and
the CNRS.
4.4.6. ( )-o-Anisylchlorophenylthiophosphoryl 3h. White
1
solid; mp 89°C; Rf=0.20 (cyclohexane/AcOEt 99:1); H
NMR (CDCl3) l ppm, J Hz: 8.17 (1H, ddd, J=2, J=8,
J=18, H arom.), 7.90 (2H, ddd, J=1, J=8, J=16, H
arom.), 7.59–7.41 (4H, m, H arom.), 7.12 (1H, td, J=3,
J=8, H arom.), 6.90 (1H, t, J=8, H arom.), 3.61 (3H,
s, CH3O); 13C NMR (CDCl3) l ppm, J Hz: 159.9 (d,
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