(
)
200
A.M.A. Rocha GonsalÕes et al.rJournal of Organometallic Chemistry 553 1998 199–204
with heated plate and values are uncorrected. Mass
spectra were recorded under electron impact at 70 eV
on a HP-5899. Infrared spectra were recorded on a
Phillips PU 9800 FTIR spectrometer. Elemental analy-
ses were carried out on a Fisons EA 1108.
filtering with celite and concentrating the filtrate, a
white solid was obtained which was recrystallized in
isopropanolrdichloromethane to give the pure diphos-
1
22
w x
Ž
.
phine. M.p. 114–1168C, a y15 c1.0, CH2Cl2 . H
Ž
.
Ž D
.
Ž
.
NMR: 2.32 m, 2H ; 2.54 m, 2H ; 3.65 m, 2H ; 4.24
Ž
.
Ž
d, 2H, J 11.4, AB system ; 4.36 d, 2H, J 11.4, AB
system ; 7.10–7.42 m, 30H . C NMR: 29.2 d, JŽCP.
13
.
Ž
.
Ž
2.2. Synthesis of ligands
.
Ž
Ž
.
Ž
.
13.8, P– CH2 ; 72.3 s, Ph– CH2 ; 76.6 m, CH–CH2 ;
..
Ž
.
Ž
.
Ž
.
Ž
The 1,2-bis diphenylphosphino ethane dppe ,
127.5–128.7 m, P– Ph Cm, p , OCH2Ph Co,m, p
..
;
Ž
.
Ž
.
Ž
.
Ž
Ž
Ž
Ž
Ž
Ž
2S,3S -2,3-bis diphenylphosphino butane chiraphos ,
133.3 d, JŽCP. 16.7, P– Ph Co ; 132.5 d, JŽCP. 18.6,
.. ..
Ž
.
Ž
Ž
.
Ž
Ž
Ž
Ž
1,4-bis diphenylphosphino butane dppb , 1,3-bis di-
P– Ph Co ; 138.0 OCH2Ph Ci ; 138.3 d, JŽCP. 13.1,
31 P
.. ..
;
.
Ž
.
.
Ž
Ž
phenylphosphino propane dppp , 2 R,4R -2,4-bis di-
P– Ph Ci ; 139.1 d, JŽCP. 12.9, P– Ph Ci
y1
.
Ž
.
Ž
.
phenylphosphino pentane bdpp , were commercial
.Ž
NMR: y23; IR cm , KBr : 3066, 3053, 3027, 2884,
w
Ž
.
x
Ž
samples. A sample of Rh cod deguphos BF4 cods
1480, 1455, 1431, 1360, 1204, 1105, 1086, 1076, 1067,
q
Ž
.
Ž
.
Ž
Ž
.
Ž
.
Ž
.
1,5-cyclooctadiene; deguphoss 3R,4R -N-benzyl-3,4-
1026. mrz 639 M , 1% , 561 14 , 453 15 347 47 ,
Ž
.
.
Ž
.
Ž
.
.
Ž
.
Ž
.
bis diphenylphosphino pyrrolidine was kindly supplied
239 26 , 185 56 , 121 21 , 108 41 , 91 100 . Anal.
calc. C42 H40O2 P2: C, 78.98; H, 6.31. Found: C, 78.86;
H, 6.03.
w
Ž
by Degussa Iberica. 1,2-bis diphenylphos-
phino methyl benzene dppmb 13 and 2 R,3R -2,3-
O-isopropylidene-2,3-dihydroxy-1,4-bis diphenylphos-
phino -butane diop 14 were prepared by similar liter-
ature procedures and the characterization was in agree-
ment with the reported data.
.
x
Ž
.
w
x
Ž
.
Ž
2.2.3. Catalytic reactions
.
Ž
. w x
w
Ž
. x
The rhodium complex Rh cod Cl was prepared
2
x
w
according to the usual procedure 17 . In the tables,
conversions are measured by relative peak areas of GC.
For the identification of the reaction products, pure
samples of the reduced acrylic acids were prepared by
catalytic hydrogenation and characterized by the usual
(
) (
2R,3R -2,3-dihydroxi-1,4-bis diphenyl-
2.2.1.
)
phosphino butane diop–diol
)
(
Ž
.
.
The diphosphine diop 2 g, 4.36 mmol was dis-
Ž
.
methods NMR, IR and elemental analysis all being
known compounds. The ee were calculated by using the
Ž
solved in CH2Cl2 50 ml and 4 ml of 70% aqueous
HClO4 were added. After stirring vigorously for 30 min
at room temperature, a saturated aqueous solution of
NaHCO3 is added until neutralization and the organic
phase separated. The aqueous phase is further extracted
with dichloromethane and the combined organic ex-
tracts dried over MgSO4 and concentrated to give an oil
w
x
following reported values 18 for the optically pure
22
Ž .
compounds: N-acetyl- R -alanine
w x
Ž
q 66.5 c2,
a
w x
D
22
.
Ž .
Ž
22
H2O ; N-acetyl- S -phenylalanine a D q46.8 c1.06,
.
Ž .
w x
a D q15.5
EtOH 95% ; Methyl- R -succinic acid
Ž
.
c2.82, EtOH .
Ž
which crystallizes from ethanol as a white solid. 3.05
2.2.4. General procedure for transfer reductions using
formic acidrtriethylamine in dimethylsulphoxide
22
.
w x
Ž
mmol, 70% yield . M.p. 104–1058C. a D y35 c1.0,
1
.
Ž
.
Ž
.
CHCl3 . H NMR: 2.32 d, 4H, J 6.27 ; 2.63 bs, 2H ;
Ž
.
DMSO 3.75 ml was added to a degassed mixture of
3.65–3.71 m, 2H ; 7.22–7.41 m, 20H . 13C NMR:
Ž
.
Ž
.
w
Ž
. x
30 mmol Rh cod Cl , 72 mmol of the diphosphine
ligand and 4 mmol substrate, under nitrogen. In the case
of deguphos, 60 mmol of Rh cod deguphos BF4 were
used. The solution was stirred for 15 min at 288C, after
which triethylamine 8 mmol and 96% formic acid 20
2
Ž
.
Ž
33.6 d, JŽCP. 13.0, CH2 ; 72.1 dd, JŽCP. 8.3, 14.4,
CH ; 128.3–128.8 m, Cm, Cp ; 132.6 d, JŽCP. 18.5,
.
.
Ž
.
Ž
Ž
w
Ž
.Ž
.x
Ž
Ž
.
Co ; 133.0 d, JŽCP. 19.0, Co ; 137.7 d, JŽCP. 11.7,
31 P
.. ..
;
Ž
Ž
Ž
P–PPh Ci ; 138.1 d, JŽCP. 10.7, P–PPh Ci
Ž
.
Ž
q
Ž
.
Ž .
.
Ž
Ž
.
.
NMR: y22.6. mrz: 459 M , 1% , 458 3 , 457 0.6 ,
.
mmol were added. Reactions were monitored by re-
Ž
.
Ž
.
Ž
.
Ž
381 26 , 273 100 , 255 18 , 185 57 , 183 57 ;
moving aliquots at regular intervals, treating with diazo-
methane, and examining the product conversion by gas
chromatography. After complete conversion, 10% NaOH
was added to the reaction mixture and the precipitated
catalyst was filtered. Acidification with 10% HCl was
followed by extraction with ether and drying of com-
y1
Ž
.
IR cm , KBr : 3283, 3069, 3048, 1480, 1431, 1082,
1069, 1026, 737, 694. Anal. Calc. C28 H28O2 P2: C,
73.35; H, 6.16. Found: C, 73.34; H, 6.30.
(
)
(
2.2.2. 2R,3R -2,3-dibenzyloxy-1,4-bis diphenylphos-
)
(
)
phino butane diop–bz
A solution of 2S,3S -2,3-benzyloxy-1,4-ditosylbu-
tane 15,16 1 g, 1.64 mmol in dry THF 10 ml was
added dropwise, under N2 , at 08C, to 7.2 ml, 3.6
mmol of potassium diphenylphosphide in THF 0.5 M
Ž
.
bined organic extracts MgSO4 . The solidified product
was obtained by evaporation from ethylacetaterhexane
before measuring optical rotation.
Ž
.
w
x
Ž
.
Ž
.
Ž
.
Ž
.
2.2.5. General procedure for transfer reduction using
with stirring. The resulting solution was brought slowly
to room temperature, and stirred for an additional 2–3 h
with tlc monitoring until reaction was complete. After
formic acidrsodium formate
w
Ž
. x
20.3 mmol Rh cod Cl , 48.8 mmol of diphosphine
2
ligand, except for deguphos where 40.5 mmol of