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V. Conte et al. / Applied Catalysis A: General 381 (2010) 161–168
MeCN (70 ml). The reaction mixture was then refluxed for 48 h,
allowed to cool to ambient temperature, and poured into Et2O
(300 ml). The precipitated white solid, [C6DABCO]Br,was washed
with Et2O (5 × 50 ml), and dried in vacuo for 8 h, 9.69 g, 96% yield.
The product was characterised by 1H and 13C-NMR and if necessary
it was purified by dissolution in ca. 2 ml of CH2Cl2, per g of com-
pound followed by treatment with activated charcoal, filtration and
removal of the solvent.
Fig. 1. DABAL-Me3.
2. Experimental
1H-NMR (300.1 MHz, CDCl3): ıH 3.69 (d, 6H, J = 6.0 Hz, –CH2– on
positions 2, 6 and 7); 3.54 (t, 2H, J = 9.0 Hz, –CH2– on position 1 of
the side chain); 3.29 (t, 6H, J = 6.0 Hz, –CH2– on positions 3, 5 and
8); 1.79 (m, 2H, –CH2– on position 2 of the side chain); 1.32 (m,
6H, –CH2– of the side chain); 0.88 (t, 3H, J = 9.0 Hz, –CH3 of the side
chain). 13C-NMR (75.4 MHz, CDCl3): ıC 64.6 (C-1 side chain); 52.5
(C-2, C-6 and C-7); 45.5 (C-3, C-5 and C-8); 31.3 (C-2 side chain);
26.1 (C-3 side chain); 22.4 (C-4 side chain); 22.1 (C-5 side chain);
14.0 (C-6 side chain).
The derived [C6DABCO]Br (5.06 g, 0.02 mol) was dissolved in
5 ml of deionised water and solid NaBF4 (2.00 g, 0.02 mol) added.
The resulting homogeneous solution was vigorously stirred at r.t.
for 48 h. The solution was then extracted with CH2Cl2 (5 × 5 ml). The
collected organic phases were washed with small volumes (<5 ml)
of deionised water, until the AgNO3 test (of the aqueous phase)
was negative. The resulting yellowish organic phase was dried over
anhydrous Na2SO4, and discoloured with ca. 1 g of activated char-
coal. After stirring at r.t. overnight the solution was filtered and the
solvent removed under vacuum to afford 2.99 g (0.01 mol, 71%) of
[C6DABCO]BF4, as a white solid, with m.p. 84 ◦C.
2.1. Materials
Substrates and ligands were purchased from Sigma–Aldrich,
Alfa Aesar, Lancaster, Merck and used without further purification.
DABAL-Me3 was purchased from Sigma–Aldrich and stored under
inert atmosphere (Ar). Sulfuric acid (84% w/w) was purchased from
Pharmacos and oleum from Sigma–Aldrich.
Solvents were purchased from Fluka, Lancaster and Carlo Erba
and were either of anhydrous grade or dried according to literature
procedures [13].
The pre-catalyst Pd2(dba)3 was purchased from Sigma–Aldrich
and used as received, while PdCl2(CH3CN)2 was synthesised in 96%
yield from PdCl2 and acetonitrile, according to known literature
procedures [14].
sulfonyl)imide ([C4mim]Tf2N), 1-butyl-3-methylimidazolium
tetrafluoroborate ([C4mim]BF4) and 1-butyl-2,3-dimethyli-
midazolium tetrafluoroborate ([C4mmim]BF4) were synthesised
according to literature procedures [15–17], characterised by
1H-NMR, and stored under an inert atmosphere (Ar).
GC analyses were performed using Hewlett Packard HP
4890A and Varian 3900 instruments. The former was equipped
with a Hewlett Packard HP-5 capillary column (15 m length,
0.53 mm internal diameter, 0.15 m film thickness), while the
latter mounted a Supelco SPB-5 capillary column (30 m length,
0.25 mm internal diameter, 0.25 m film thickness). Analyses
were performed using undecane as an internal standard (with
HP 4890A) or dodecane as an external standard (with Varian
3900). ESI-MS analysis were performed using a Bruker MicroTOF
instrument.
1H-NMR (300.1 MHz, CDCl3): ıH 3.36 (d, 6H, J = 6.3 Hz, –CH2– on
positions 2, 6 and 7); 3.27 (m, overlap of 8H, –CH2– on positions 3,
5, 8 of the ring and 1 of the side chain); 1.71 (m, 2H, –CH2– position
2 of the side chain); 1.33 (m, 6H, –CH2– positions 3, 4 and 5 of the
side chain); 0.89 (t, 3H, J = 6.6 Hz, –CH3 position 6 of the side chain).
(XphosSO3H)
1H-NMR spectra were recorded using Bruker Avance 300 and
400 spectrometers, operating at 300.1 and 400.1 MHz, respectively.
13C-NMR analyses were performed with a Bruker Avance 300 and
400 spectrometer, operating at 75.4 and 100.6 MHz respectively.
The residual signal of the solvent (CDCl3 and CD3OD) was used
as internal reference. 31P-NMR analyses were performed with a
Bruker Avance 400 and Bruker Avance 300 spectrometers, oper-
ating at 162.0 and 121.4 MHz, respectively; PPh3 was used as a
reference compound. All deuterated solvents were purchased form
Sigma–Aldrich.
The material was attained by a modification of a literature
preparation [19]. Solid XPhos (433.0 mg, 0.90 mmol) was stirred
in CH2Cl2 (3.0 ml) under an inert atmosphere in an appropriate
flask. The flask was immersed in a dry ice-acetone bath maintained
at −40 ◦C and concentrated H2SO4 (84%) (1.0 ml) was added drop-
wise, causing the solution to turn yellow. Then highly concentrated
H2SO4 oleum (20% SO3) (CARE! Corrosive) (3.0 ml) was carefully
added dropwise causing the solution to darken. The mixture was
stirred vigorously for 24 h, allowing the bath to reach room temper-
ature. After 24 h, crushed ice was added to the solution. The upper
aqueous phase was decanted, and the CH2Cl2 solution diluted by
adding portions of Et2O. At an approximate 2:1 ratio of Et2O:CH2Cl2
a beige powder slowly precipitated. The powder was filtered off
and dried under high vacuum (0.1 mmHg) at room temperature
for 6 h. The compound obtained, 540.3 mg (98%), is the fully pro-
tonated analogue of Buchwald XPhosSO3Na [19] and was used as
obtained. 1H-NMR (400.1 MHz, CD3OD): ıH 8.12 (m 1H, ArH); 7.98
(m 1H, ArH); 7.82–7.90 (m, 3H, ArH); 7.69 (m 1H, ArH); 2.80 (m, 1H,
PH); 2.38 (hep, 2H, J = 7.1 Hz, 2 x CHMe2); 1.73–2.08 (m, 9H, Cy);
tetrafluoroborate ([C6DABCO] BF4)
This IL, which has both basic and cationic motifs, was syn-
thesised (see Reaction 1) by slight modification of a literature
procedure [18]. Under a nitrogen atmosphere, 1-bromohexane
(6.3 ml, 44.6 mmol, 1.00 equiv.) was added over 30 min to a solu-
tion of freshly sublimed DABCO (10.0 g, 89.1 mmol, 2.00 equiv.), in
Reaction 1. Synthesis of 1-hexyl-4-aza-1-azaniabicyclo[2.2.2]octyl tetrafluoroborate [C6DABCO] BF4.