N,N,NЉ,NЉ-tetraethyldiethylenetriamine (TEDETA),38 which
were synthesized according to literature procedures. Solvents
and chlorodiphenylphosphine were distilled prior to use,
otherwise the chemicals were used as received. Solvents used
in the synthesis and manipulation of the phosphines were
thoroughly degassed with N2 or Ar prior to use.
The NMR spectra were recorded at 21 ЊC on a Varian Unity
300 MHz spectrometer with an observation frequency of 121
MHz for 31P (referenced to 85% H3PO4) and of 300 MHz for
1H (referenced to SiMe4), IR Spectra on a Nicolette FT-IR
spectrometer as Nujol mulls or KBr plates and UV/VIS spectra
on a Milton Roy 3000 spectrophotometer. The pH measure-
ments for the NMR experiments were carried out using
a standard glass electrode, calibrated with standard buffer
solutions at pH 1 and 4.
g, 34 mmol) was dissolved in methanol (150 ml). The pH of
the solution was adjusted to ≈6 with methanesulfonic acid.
4-(Diphenylphosphino)benzaldehyde (5.0 g, 17.2 mmol) was
added together with NaBH3(CN) (0.76 g, 12 mmol). The mix-
ture was stirred at room temperature for 16 h after which the
solvent was evaporated and the residue taken up in 1 M HCl
(100 ml) and extracted with CH2Cl2 (2 × 25 ml). The pH of the
aqueous phase was set to ≈12 with KOH after which it was
extracted with benzene (2 × 50 ml). The combined benzene
phases were dried over MgSO4 and evaporated. Yield 6.1 g
(72%) crude product which can be purified by chromatography
as in method b.
Method b. N,N,NЉ,NЉ-Tetraethyldiethylenetriamine (51.0 g,
0.23 mol) was added dropwise with stirring to a solution of 4-
bromobenzyl bromide (57.0 g, 0.23 mol) dissolved in absolute
ethanol (400 ml) in a three-necked flask. The reaction mixture
was stirred for 15 min and then refluxed for 2 h. After cooling,
the ethanol was evaporated and the residue taken up in ben-
zene, washed with 10% KOH and saturated NaCl solution and
then dried over MgSO4. The benzene was removed and the
crude product 1 distilled at 180–185 ЊC/3 mbar. Yield 74 g
(84%) pale yellowish oil. 1H NMR δ (CDCl3): δ 1.0 (t); 2.5 (m);
3.6 (s); 7.1 (d, aromatic) and 7.4 (d, aromatic).
Hydroformylation reactions
The hydroformylations were performed in a glass vessel con-
tained in a Roth 50 ml stainless steel autoclave with a 1:1
CO:H2 gas mixture at 20 bar pressure. In the homogeneous
experiments 0.04 mmol phosphine and 0.004 mmol rhodium
precursor together with the internal standard (3-methyl-
naphthalene) were dissolved in 5 ml of toluene in the glass
vessel. Syngas was then bubbled through the solution for 10 min
after which 500 µl 1-hexene were added. The glass vessel was
placed in the autoclave together with a magnetic stirring bar.
The autoclave was closed and pressurised/depressurised 3 times
before finally setting the pressure and temperature.
A three-necked flask containing magnesium (2.1 g, 86 mmol)
and dried and degassed THF (200 ml) under argon was
equipped with a dropping funnel charged with compound 1
(30.0 g, 78 mmol). After addition of a crystal of I2 and a few ml
of 1 to initiate the Grignard reaction, the rest of the contents
was added in small portions. When all 1 had been added the
reaction solution was stirred for 30 min and then refluxed for
1 h. After cooling to 0 ЊC chlorodiphenylphosphine (17.2 g,
78 mmol) was slowly added dropwise to the deep red solution.
The solution was stirred for 30 min at 0 ЊC and then refluxed
for 16 h. After cooling to room temperature the reaction was
quenched with 10% NH4Cl solution (40 ml) . The solvent was
evaporated and the residue taken up in acidified (HCl) water
and washed three times with CH2Cl2. The pH of the aqueous
phase was set to 12 with KOH solution and washed three times
with diethyl ether. The ether phases were combined, washed
with saturated NaCl solution and dried over MgSO4 after
which the ether was evaporated, leaving a yellow oil. Yield: 31 g
(82%). The crude N3P was further purified by column chrom-
Recycling of the catalysts
After two hours of reaction time the autoclave was cooled to
0 ЊC and depressurised. The reaction solution was transferred
to an argon filled Schlenk tube after which the catalyst was
extracted with 3 × 2 ml of acidified water (pH ≈ 1 with
methanesulfonic acid). The now uncoloured organic phase was
separated and the pH in the combined aqueous phases was set
to 12 with a KOH solution. The aqueous phase was extracted
with 3 × 1.7 ml toluene and the combined toluene phases used
in another catalytic run. The ratio of the TOF in the two runs is
taken as a measure of the retained activity.
Biphasic catalysis
1
atography (silica gel 60, ethyl acetate–triethylamine 10:1). H
The compound N3P (20 mg, 0.04 mmol) was added to a solu-
tion of 8 µl methanesulfonic acid in 5 ml of water in a glass
vessel under Ar. After stirring for a few minutes, 1.0 mg (0.004
mmol) [Rh(CO)2(acac)] was added. After dissolution of the
solids the pH was set to ≈5 with KOH after which the internal
standard and the substrate (500 µl) dissolved in toluene (5 ml)
were added. The resulting two phase mixture was then treated
in exactly the same manner as for homogeneous runs.
NMR (CDCl3): δ 1.0 (t); 2.5 (m); 3.6 (s); and 7.3 (m, aromatic).
31P NMR (CDCl3): δ Ϫ5.1 (s). Calc. for C31H44N3P: C, 76.1; H,
9.0; N, 8.6; P, 6.3. Found: C, 76.3; H, 9.1; N, 8.8; P, 6.4%.
Methylation of N3P, formation of methyl iodide salt. The
phosphine oxide of N3P was synthesized in a similar way to
N3P (method b), using diphenylphosphinoyl chloride instead
of chlorodiphenylphosphine, yielding a yellowish oil (77%).
The oxide was dissolved in methanol and 5 equivalents of
methyl iodide were added dropwise. The reaction mixture was
stirred for 16 h and evaporated. The residue was dissolved in
acetonitrile, an excess (5 equivalents) of SiCl3H added dropwise
and the mixture refluxed for 17 h followed by removal of
remaining SiCl3H by distillation. Water was added and the solid
product was filtered off and discharged. The remaining solution
was evaporated leaving a yellow solid. Recrystallisation from
acetonitrile–diethyl ether yielded a white powder. 1H NMR
(CDCl3): δ 1.3 (t); 2.2 (s); 3.0 (s); 3.5 (q); 3.6 (t); 3.8 (t); 4.4 (s);
and 7.3–7.8 (m, aromatic). 31P NMR (D2O): δ Ϫ3.9 (s).
Crystal data and data collection
The data were collected at room temperature on a Siemens
SMART CCD diffractometer. The structure was solved by dir-
ect methods using the SHELXTL PLUS program package.39
Crystal data. C37H51N3O3PRh, M = 719.27, triclinic, space
¯
group P1, a = 8.937(2), b = 14.420(3), c = 15.427(3) Å, α =
82.42(3), β = 88.44(3), γ = 75.80(3)Њ, V = 1910.4(7) Å3, T = 273
K, Mo-Kα radiation, λ = 0.7107 Å, Z = 2, Dc = 1.253 Mg m3,
F(000) = 758, yellow plate with dimensions 0.25 × 0.14 × 0.04
mm, µ = 0.525 mmϪ1, 15771 reflections measured, 10954 unique,
used in refinements, Rint = 0.0433, R = 0.059, RЈ = 0.120).
CCDC reference number 186/1701.
[Rh(CO)(N3P)(acac)]. The compound N3P (100 mg, 0.2
mmol) was dissolved in CH2Cl2 (5 ml), [Rh(CO)2(acac)] (53 mg,
0.2 mmol) in CH2Cl2 (5 ml) added dropwise and the solution
stirred at room temperature for 30 min. After evaporation the
residue was taken up in n-pentane (5 ml). Storing at Ϫ30 ЊC
graphic files in .cif format.
Syntheses
1
overnight yielded 130 mg (90%) of yellow crystals. H NMR
N3P. Method a. N,N,NЉ,NЉ-tetraethyldiethylenetriamine (7.3
(CDCl3): δ 1.0 (t); 1.6 (s); 2.1 (s); 2.5(m); 3.6 (s); 5.4 (s) and 7.3–
J. Chem. Soc., Dalton Trans., 1999, 4187–4192
4191
Karlsson, Magnus
