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tained by allowing the compound to crystallise slowly from the fil-
trate mentioned above at 48C over 3 days.
Preparation of copper(I) benzylamide (5): A solution of copper(I)
mesityl (439 mg, 2.40 mmol) in tetrahydrofuran (1 mL) was treated
with benzylamine (288 mL, 2.64 mmol) at room temperature. After
stirring at room temperature for 2 min, it was evaporated under
vacuum to give a yellow residue. The yellow residue was stirred in
n-hexane (6 mL) for 30 min at room temperature and then the re-
sultant solid was filtered. The filtered solid was washed with n-
hexane (25 mL) and then dried under vacuum to give the prod-
Preparation of copper(I) 2,2,6,6-tetramethylpiperidide (2): A so-
lution of 2,2,6,6-tetramethylpiperidine (3.40 mL, 20.00 mmol) in tet-
rahydrofuran (10 mL) was treated dropwise with n-butyllithium in
hexanes (12.50 mL, 20.00 mmol, 1.6m) at 08C. After stirring at 08C
for 5 min, the solution was transferred dropwise to a suspension of
copper(I) chloride (2.178 g, 22.00 mmol) in tetrahydrofuran (65 mL)
at 08C. After complete addition, the reaction mixture was allowed
to come to room temperature and was stirred for 40 min, after
which it was then filtered through Celite. The filtrate was then con-
centrated under reduced pressure and then kept at À258C. After
1
uct as a white powder (304 mg, 1.79 mmol, 75%). H NMR
(
400 MHz, [D ]benzene, 248C, TMS): d=0.13–0.34 (m, 1H; N-H),
6
3
.80–3.97 (m, 2H; CH ), 7.04–7.15 (m, 1H; p-C H ), 7.17–7.38 ppm
2 6 5
13
(m, 4H; o-C H and m-C H ); C NMR (101 MHz, [D ]benzene, 228C,
6 5 6 5 6
TMS): d=52.6 (s; CH ), 126.4 (s; Ph carbon), 127.8 (s; Ph carbon),
2
5
days, crystallised solid was isolated by filtration and then dried
1
28.3 (s; Ph carbon), 146.6 ppm (s; Ph carbon); elemental analysis
under vacuum to afford the desired product as a white solid
calcd (%) for C H CuN: C 49.55, H 4.75, N 8.25; found: C 49.39, H
7
8
1
(
1.751 g, 8.59 mmol, 43%). H NMR (400 MHz, [D ]benzene, 228C,
6
4
.65, N 8.35.
TMS): d=1.54–1.60 (m, 4H; g-CH ), 1.69–1.81 ppm (m, 14H; CH
2
3
1
3
and b-CH2); C NMR (101 MHz, [D ]benzene, 228C, TMS): d=20.1
Isolation of the intermediate in the synthesis of copper(I) piperi-
dide (6): A solution of copper(I) mesityl (365 mg, 2.00 mmol) in tet-
rahydrofuran (2 mL) was treated with piperidine (988 mL,
10.00 mmol) and stirred at room temperature for 5 min after which
a yellow precipitate was present. The solid was filtered and then
washed n-hexane (33 mL) and then dried under vacuum to
afford the product as a yellow powder (225 mg, 0.25 mmol, 50%).
6
(
s; g-CH ), 38.0 (s; CH ), 43.3 (s; b-CH ), 57.7 ppm (s; a-C); elemental
2 3 2
analysis calcd (%) for C H CuN: C 53.04, H 8.90, N 6.87; found: C
9
18
5
2.83, H 9.08, N 6.85. Colourless crystals suitable for X-ray diffrac-
tion were obtained by allowing the compound to crystallise slowly
from the filtrate mentioned above at 48C over 4 days.
Preparation of copper(I) pyrrolidide (3): A solution of pyrrolidine
1
3
H NMR (400 MHz, [D ]benzene, 218C, TMS): d=0.47 (p, J(H,H)=
6
(
1.11 mL, 13.50 mmol) in tetrahydrofuran (10 mL) was treated drop-
5
1
6
.4 Hz, 2H; N-H), 1.01–1.20 (m, 12H; b-CH2 and g-CH ), 2.04 (s,
2
wise with n-butyllithium in hexanes (5.20 mL, 13.00 mmol, 2.5m) at
room temperature to give a colourless solution. After stirring for
2H; p-CH ), 2.18–2.35 (m, 8H; a-CH ), 2.93 (s, 24H; o-CH ),
3
2
3
13
.70 ppm (s, 8H; Ar-H); C NMR (101 MHz, [D ]benzene, 228C,
6
1
0 min, the solution was transferred dropwise to a suspension of
TMS) d=21.0 (s; p-CH ), 24.7 (s; g-CH ), 27.1 (s; b-CH ), 28.8 (s; o-
3
2
2
copper(I) chloride (1.39 g, 14.00 mmol) in tetrahydrofuran (50 mL)
at room temperature. After complete addition, the reaction mix-
ture was stirred for 25 min and then filtered through Celite. The fil-
trate was concentrated under reduced pressure until a small
amount of white solid had precipitated and then kept at À258C
overnight, after which the product had crystallised. The solid was
separated by filtration, washed with n-hexane (25 mL) and then
dried under vacuum to give the product as a white crystalline
CH ), 47.0 (s; a-CH ), 126.0 (s; Ar C-H), 138.2 (s; Ar C-CH ), 140.1 (s;
3
2
3
Ar C-CH ), 152.3 ppm (s; Ar C-CH ); Unable to acquire satisfactory
3
3
elemental analysis due to decomposition of the complex. Yellow
crystals suitable for X-ray diffraction were obtained by treating a fil-
tered yellow solution of copper(I) mesityl in THF with piperidine
and then leaving it to stand at room temperature overnight.
DFT calculations: All calculations were performed with the Gaussi-
[
82]
[83,84]
solid, which was stored at À258C (917 mg, 6.86 mmol, 53%).
an 09 package. The B3LYP DFT method
try optimisations with the SVP basis set
31G(d)
was used for geome-
for Cu and 6–
1
[85,86]
H NMR (400 MHz, [D ]benzene, 238C, TMS): d=1.44–1.62 (m, 4H;
6
13
[87,88]
b-CH2), 3.11–3.31 ppm (m, 4H; a-CH2);
C NMR (101 MHz,
for C, H, N and Si. Solvation effects on the structures
[
D ]benzene, 238C, TMS): d=26.6 (s; b-CH ), 26.8 (s; b-CH ), 26.9 (s;
were then finally taken into account by performing self-consistent
reaction field (SCRF) calculations using the CPCM polarisable con-
6
2
2
b-CH ), 54.9 (s; a-CH ), 55.3 (s; a-CH ), 55.5 ppm (s, a- CH ); ele-
mental analysis calcd (%) for C H CuN: C 35.94, H 6.03, N 10.48;
2
2
2
2
[89,90]
ductor calculation model with benzene set as the solvent.
All
7
8
found: C 35.71, H 5.85, N 10.33.
optimised geometries were confirmed as energy minima with no
imaginary frequencies using frequency calculations at the same
level of theory. All volume calculations were performed on the fully
optimised geometries with the density contour chosen as 0.02
Preparation of copper(I) piperidide (4): A solution of copper(I)
mesityl (1.462 g, 8.00 mmol) in tetrahydrofuran (10 mL) was treated
with piperidine (3.95 mL, 40.00 mmol) at room temperature. Soon
after the addition, a yellow precipitate formed which slowly dis-
solved over time with stirring (can take over 24 h to dissolve). The
resultant pale yellow solution was stirred at room temperature for
À3
electronsBohr and the number of Monte Carlo points was in-
creased to 100 to minimise variation. The calculations were repeat-
ed 10 times for each compound and the mean of the recommend-
ed radii from the volume calculation outputs were calculated and
3
days, during which a white precipitate had formed. The mixture
was evaporated to dryness under vacuum and then n-hexane
10 mL) was added to suspend a white solid. The solid was separat-
used as rcalc
.
(
Stoichiometric CÀN coupling reactions between the copper(I)
amide complexes and iodobenzene: [D ]DMSO or [D ]benzene
ed by filtration, washed with n-hexane (25 mL) and then dried
6
6
under vacuum to afford the product as a white powder (781 mg,
(1 mL) was added to a screw-cap vial containing the copper(I)
amide complex (0.10 mmol), 1,10-phenanthroline (18 mg,
0.10 mmol; if required) and a magnetic stirring flea followed by
mesitylene (14.0 mL, 0.10 mmol) as an internal standard and then
iodobenzene (16.8 mL, 0.15 mmol) in a nitrogen-filled glovebox.
The vial was capped tightly and then taken out of the glovebox.
The mixtures were then stirred at 808C using an oil bath for 18 h.
The contents of the vial were then passed through a syringe filter
to remove any solid in a glovebox or nitrogen-filled glove bag into
1
5
.29 mmol, 66%). H NMR (400 MHz, [D ]benzene, 238C, TMS): d=
6
1
.51–1.76 (m, 6H; b-CH and g-CH ), 3.14–3.37 ppm (m, 4H; a-CH );
2
2
2
1
3
C NMR (101 MHz, [D ]benzene, 238C, TMS) d=27.0 (s; g-CH ),
6
2
3
3.7 (s; b-CH ), 34.0 (s; b-CH ), 34.3 (s; b-CH ), 56.8 (s; a-CH ), 57.0
2 2 2 2
(
s; a-CH ), 57.2 ppm (s; a-CH ); elemental analysis calcd (%) for
2 2
C H CuN: C 40.66, H 6.82, N 9.48; found: C 40.61, H 6.84, N 9.36.
5
10
Colourless crystals suitable for X-ray diffraction were obtained by
leaving the pale yellow solution mentioned above at room temper-
ature over 3 days.
1
a NMR tube. The filtered solution was then analysed by H NMR
Chem. Eur. J. 2015, 21, 7179 – 7192
7190 ꢀ 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim