A. J. L. Pombeiro, F. C. Guedes da Silva, M. N. Kopylovich et al.
+
[
M+H] , 182 (8); elemental analysis calcd (%) for C
H 6.71, N 31.09 found: C 53.36, H 6.53, N 31.73.
NC(Me)CHC(Me)NCNHC
d=1.20 (t, J(H,H)=6.9 Hz, 3H; CH
(H,H)=6.9 Hz, 2H; CH CH ), 6.80 ppm (s, 1H; CH); C{ H} NMR
O): d=13.3 (CH CH ), 22.5 (CH ), 63.6 (CH CH ), 114.7 (CH), 157.9
NC=N), 161.6 (NHC=NH), 167.5 ppm (CH C=N); IR (KBr, selected
(NꢁH); 2988, 2960 (w) n(CꢁH); 1643,
(C=C); 1542, 1524 (s) d
(NꢁH); 1437 (m),
8
H
12
N
4
O: C 53.32,
similar way, but with the atmospheric air being taken up through the
upper part of the reflux condenser. Under typical conditions, the reaction
mixtures were prepared as follows: benzyl alcohol (3.06 mmol, 320 mL),
1
A
T
N
T
E
N
N
(=NH)OEt (22): Yield 72%; H NMR (D
2
O):
2 3
catalyst (1 mol%), TEMPO (5 mol%) and K CO (1.00 mmol, 33 mol%;
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
CH
2
), 2.29 (s, 6H; CH
3
C=N), 4.07
1
3
1
as a base) were added to water (10 mL). All the above mol% are versus
the substrate. For the reactions under elevated pressure, a stainless steel
reactor (13.0 mL) was used. In this case, the reactor was loaded with re-
(
(
(
q, J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
2
D
2
3
2
3
3
2
3
agents and solvent (5.0 mL of water) and then pressurised with O
10 bar) from a dioxygen cylinder. The reaction solutions in all cases
2
bands): n˜ =3330 (sh), 3195 (br) n
A
H
U
G
R
N
N
ACHTUNGTRENNUNG
(
1
1
616, (s) n
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
H
U
G
R
N
N
ACHTUNGTRENNUNG
ꢁ
1
+
were vigorously stirred using magnetic stirrers. The desired reaction tem-
perature (in the 25–808C range) was achieved using an oil bath. The re-
action mixtures after the oxidations were neutralised by appropriate
amounts (typically ca. 1.0 mL) of 1m HCl, and then ethyl acetate
384 (s), 1105 (s), 809 (m), 875 (m), 598 cm (m); ESI -MS (in H
2
O):
+
m/z (%): 195 (100) [M+H] , 196 (13); elemental analysis calcd (%) for
O: C 55.65, H 7.27, N 28.85; found: C 55.12, H 6.94, N 28.34.
NC(Me)CHC(Me)NCNHC(=NH)OCH CH OMe (23): Yield 80%;
O): d=2.31 (s, 6H; CH C=N), 3.32 (s, 3H; CH O), 3.65 (t,
(H,H)=4.2 Hz, 2H; CH ), 4.22 (t, J(H,H)=4.2 Hz, 2H; CH ), 6.81 ppm
s, 1H; CH); C{ H} NMR (D O): d=22.5 (CH ), 58.0 (CH O), 65.6
CH ), 69.8 (CH ), 114.8 (CH), 160.1 (NC=N), 162.2 (NHC=NH),
69.0 ppm (CH C=N); IR (KBr, selected bands): n˜ =3362, 3188 (br)
n(NH); 2898, 2860 (w) n (C=N); 1544 (s) d
(CꢁH); 1664(s), 1584 (s) n (Nꢁ
H); 1408 (m), 1125 (s), 803 (s), 652 (m), 618 (m), 562 cm (m); ESI -MS
9 14 4
C H N
2
2
(
10.0 mL) was added for the extraction. The organic phase was analyzed
1
H NMR (D
2
3
3
by gas chromatography in the presence of acetophenone (150 mL) as an
internal standard. Blank tests were performed under typical reaction con-
ditions in the absence of the Cu catalyst and showed the formation of
only small amounts (<10%) of benzaldehyde.
J
(
(
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
A
H
U
G
R
N
U
G
2
1
3
1
2
3
3
2
2
1
3
Peroxidative oxidation of alcohols with TBHP: Three methods were used
for this type of oxidation: a MW-assisted process (method A), a reaction
in a sealed tube (method B) and conventional heating with a condenser
A
C
H
T
U
N
G
T
R
E
N
N
U
N
A
H
U
G
R
N
N
ACHTUNGTRENNUNG
ꢁ
1
+
+
(
(
2
in H
%) for C10
5.00.
2
O): m/z (%): 225 (100) [M+H] , 226 (12); elemental analysis calcd
(
method C).
16 4 2
H N O
: C 53.56, H 7.19, N 24.98; found: C 52.97, H 7.02, N
Method A: The alcohol substrate (5 mmol), TBHP (10 mmol) and the
copper(II)–triazapentadienato complex (usually 0.01 mmol) were added
to a cylindrical Pyrex tube that was then closed and placed in the focused
microwave reactor. The system was left under stirring and irradiation for
Preparation of triazapentadiene salts: The reaction of the cationic cop-
per(II)–triazopentadiene complexes 6, 7 and 9 with an excess amount
20 equiv) of 2,4-pentanedione (Hacac) in water at 258C in a few minutes
yields the triazopentadiene salts 24–26 and a blue solid characterised as
Cu(acac) ]. The procedure for the [Cu(acac) ] separation is similar to
that discussed above. Further evaporation of the reaction mixture gave
an oil. Washing the mixture with acetone allowed products 24–26 to be
separated as white solids.
(
1
0–240 min at 50–808C. After the reaction, the mixture was allowed to
cool down, and MeCN (5 mL) was added. Small aliquots (ca. 0.2 mL)
were then removed, mixed with Et O (ca. 1:5 v/v), centrifuged and sub-
[
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
2
A
H
U
G
R
N
N
2
2
jected to GC analysis. A power of 10 W was selected for all experiments,
since we have found that 5 W is not sufficient to maintain the desired re-
action temperature, and a higher power (e.g., 20 W) does not significantly
affect the product yield.
1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[NH=C
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(OMe)NC
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(NH
2
A
H
N
T
E
N
N
(AcO) (24): Yield 92%;
H NMR
O);
O), 161.1
COO); IR (KBr, se-
(CꢁH); 1673 (s) n
(C=O);
(NꢁH); 1399 (s), 1181 (m), 999 (m), 879
(
CD
3
1
OD): d=1.90 (s, 3H; CH
3
COO), 3.78 ppm (s, 3H; CH
OD): d=24.3 (CH COO), 55.5 (CH
OC=NH), 164.8 (NHC=NH), 180.6 ppm (CH
(NꢁH); 2753 (w) n
(C=N); 1561, 1543 d
3
Method B: The substrate (5 mmol), TBHP (10 mmol) and the
copper(II)–triazapentadienato complex (0.01 mmol) were added to a cy-
lindrical Pyrex tube that was then closed and placed in the heating
1
3
C{ H} NMR (CD
CH
3
3
3
(
3
3
lected bands): n˜ =3136 (m) n
623 (s) n
w), 832 (m), 804 (m), 709 cm (m); ESI -MS (in MeOH): m/z (%): 117
A
H
U
G
E
N
N
A
H
U
G
R
N
U
G
ACHTUNGTRENNUNG
(
508C) oil bath. The system was left under stirring by a magnetic stirrer
1
(
(
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
ACHTUNGTRENNUNG
for a certain time. After the reaction, the mixtures were treated like
those described in method A.
ꢁ
1
+
+
100) [MꢁAcO] , 118 (5); elemental analysis calcd (%) for C
5
H
12
N
4
O
3
:
Method C: The substrate (5 mmol), TBHP (10 mmol) and the
copper(II)–triazapentadienato complex (0.01 mmol) were added to a
round-bottomed flask equipped with a condenser and placed in a heating
oil bath. The system was left under stirring by a magnetic stirrer for a
certain time. After the reaction, the mixtures were treated like those de-
scribed in method A
C 34.09, H 6.87, N 31.80; found: C 33.75, H 7.24, N 31.47.
1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
[NH=C
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(OEt)NC
(H,H)=6.5 Hz, 3H; CH
.10 ppm (q, J(H,H)=6.5 Hz, 2H; CH
3.3 (CH CH ), 23.2 (CH COO), 65.3 (CH
COO); IR (KBr, selected
bands): n˜ =3400, 3125 (br) n(NH); 2992, 2891 (w) n (C=O);
(CꢁH); 1655 n
(NꢁH); 1420 (m), 1384 (s), 1096 (m), 1018 (m),
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(NH
2
A
H
U
G
R
N
U
G
2
O):
d=1.18 (t, J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
CH
CH
2
), 1.78 (s, 3H; CH
); C{ H} NMR (D
CH ), 160.3 (CH
3
COO),
O): d=
CH OC=
1
3
1
4
1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
2
2
3
2
3
2
3
2
NH), 162.3 (NHC=NH), 181.5 ppm (CH
3
Recyclisation of catalyst 1: Conditions: 1-phenylethanol (5 mmol), 1
A
T
N
T
E
N
N
ACHTUNGTRENNUNG
(
0.1 mmol), MW, 30 min, 808C.
1
8
[
3
648 n
ACHTUNGTRENNUNG( C=N); 1559 (s) d ACTHUNGTRENNNUG
ꢁ1
+
Method A: The aqueous phase from the post-reaction mixture, after re-
moving the organic phase (containing the substrate, product and oxidant)
was used for the next run (with new loadings of substrate and oxidant).
This procedure was repeated six times.
18 (m), 654 cm
H
2
O): m/z (%): 131 (100)
: C
+
MꢁAcO] , 132 (7); elemental analysis calcd (%) for C
7.89, H 7.42, N 29.46; found: C 38.03, H 7.77, N 29.39.
[HN=C(NH )-NH-C(OCH CH OCH )=NH](AcO) (26): Yield 87%;
H NMR (D O): d=1.79 (s, 3H; CH COO), 3.29 (s, 3H; CH O), 3.62 (t,
(H,H)=4.4 Hz, 2H; CH ), 4.21 ppm (t, J(H,H)=4.4 Hz, 2H; CH );
O): d=23.2 (CH COO), 58.1 (CH O), 67.0 (CH ), 69.8
), 159.6 (CH OC=NH), 162.5 (NHC=NH), 181.4 ppm (CH COO);
IR (KBr, selected bands): n˜ =3328, 3170 (br) n(NH); 2988, 2945 (w) n-
(C=O); 1617 (s) n(C=N); 1587 (s) d
(CꢁH); 1630 (m) n (NꢁH); 1437 (s),
410 (s), 1384 (s), 1105 (m), 809 (m), 655 (m), 595 cm (m); ESI -MS
6 14 4 3
H N O
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
3
2
3
ACHTUNGTRENNUNG
1
Method B: The aqueous phase of the post-reaction mixture, after remov-
ing the organic phase (containing the substrate, product and oxidant) was
evaporated until dryness with air flow and then the solid residue was
used for the next run (with new loadings of substrate and oxidant). This
procedure was repeated six times.
2
3
3
J
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
H
U
G
R
N
U
G
2
1
3
1
C{ H} NMR (D
CH
2
3
3
2
(
2
2
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
H
U
G
E
N
N
ACHTUNGTRENNUNG
ꢁ
1
+
1
(
+
ꢁ
in H
2
O): m/z (%): 161 (100) [MꢁAcO] , 162 (7); ESI -MS (in H
2
O):
ꢁ
m/z (%): 59 (100) [AcO] ; elemental analysis calcd (%) for C
7
H
16
N
4
O
4
:
Acknowledgements
C 38.18, H 7.32, N 25.44; found: C 38.30, H 7.60, N 25.41.
Catalytic studies
This work has been partially supported by the Foundation for Science
and Technology (FCT, Portugal), its PPCDT (FEDER funded) and “Sci-
ence 2007” programs. M.N.K., J.L., Y.Y.K. and P.J.F. express gratitude to
the FCT for working contracts and post-doc fellowships. We also ac-
knowledge Dr. C. Oliveira for the ESI-MS analyses.
Aerobic oxidation: Oxidation reactions under atmospheric pressure were
typically carried out in 100 mL two-necked round-bottomed flasks
equipped with a condenser and connected to a balloon filled with O
Before the experiment, the apparatus was vacuumed and flushed with O
2
.
2
(
three times). The experiments with air as oxidant were performed in a
912
ꢃ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 899 – 914