N-arylation of 1,4,7,10-tetraazacyclododecanes

Article abstract of DOI:10.1055/s-2001-17531

Palladium-catalyzed N-arylation reactions provide acces to N-aryl-substituted and N-aryl-bridged 1,4,7,10-tetraazacyclododecanes. Yields of arylation products are low with simple haloarenes, whereas reactions with pyridine derivatives give substituted cyclens in moderate to satisfactory yields.

Full text of DOI:10.1055/s-2001-17531

1818
PAPER
N-Arylation of 1,4,7,10-Tetraazacyclododecanes
N
-Arylation of 1,4,7,1
i
0-Tetra
c
azacyclodo
h
decanes ael Subat, Burkhard König*
Institut für Organische Chemie, Universität Regensburg, 93040 Regensburg, Germany
Fax +49(941)5431717; E-mail: burkhard.koenig@chemie.uniregensburg.de
Received 1 May 2001; revised 3 July 2001
Abstract: Palladium-catalyzed N-arylation reactions provide acces
to N-aryl-substituted and N-aryl-bridged 1,4,7,10-tetraazacy-
clododecanes. Yields of arylation products are low with simple ha-
loarenes, whereas reactions with pyridine derivatives give
substituted cyclens in moderate to satisfactory yields.
Keywords: azamacrocycle, palladium, N-arylation
Azamacrocycles, such as triazacyclononane, tetraazacy-
clododecane (cyclen) or tetraazacyclotetradecane (cy-
clam), have found many applications as ionophors for
transition metal binding.1–7 In addition, their Lewis-acidic
metal complexes have been used as binding sites for
Lewis-basic ligands in artificial receptors.8–12 A variety of
substituted cyclens has been already reported. The main
Scheme 1 Synthesis of aryl-bridged biscyclen by twofold SNAr re-
route for functionalization starts from the commercially
available parent azamacrocycle and uses alkylation or
acylation reactions13,14 of one or more nitrogen atoms to
introduce additional functionality. However, these reac-
tions lead to ligands with limited preorganization or re-
duced binding ability. N-Aryl-substituted and N-aryl-
bridged cyclens could be of advantage in the design of se-
lective ionophors or artificial receptors, but so far only the
synthesis of very few compounds of this kind has been re-
ported,15 and a general synthetic approach is lacking. We
have therefore adapted recently developed palladium-cat-
alyzed N-arylation procedures16,17 towards the functional-
ization of cyclens and report our findings in this paper.
action
actions under mild conditions with primary and secondary
amines and haloarenes, which are not particularly electron
poor. The work has been comprehensively reviewed. In
two papers the results of palladium-catalyzed N-arylation
of larger azamacrocycles and mixed O, N-macrocycles
have been reported.26,27 Our first attempts to transfer the
methodology to the small azamacrocycle 1 by arylation of
Cbz-protected compound 1b with iodobenzene (entry 1,
Table 1) under standard conditions using a palladium(0)
source and BINAP as a ligand gave no conversion. Ex-
change of the protecting groups to Boc protection, as in
1a, gave a low 8% isolated yield of arylation product 6a
(entry 2), which corresponds to 21% if corrected by unre-
acted starting materials. Neither longer reaction times (en-
try 3), subsequent addition of palladium catalyst,
stoichiometric amounts of ligand, THF as solvent (entry
4) nor a palladium(II) salt as catalyst precursor (entry 5)
improved yield and conversion. The use of bromobenzene
as an arene coupling partner and DPPF as a ligand were
advantageous (entries 6–8). Yields of the product reached
63%, as adjusted by recovered starting material, but reac-
tion conversions remained unsatisfactory. The use of bro-
mobenzene as solvent (entry 9, compare with 10),
increased amounts of palladium source or catalyst (entry
11) or the addition of 18-crown-6, which allowed reac-
tions with other substrates even at room temperature,28 did
not improve the conversion or coupling yields (entries 12–
14) in this reaction. For comparison, 5b was reacted with
diethylamine (entry 28) giving the substitution product
N,N-diethylaniline in nearly quantitative yield. The mo-
lecular model of 1a (Figure 1) provides a possible expla-
Classical N-arylation procedures use the reaction of pri-
mary or secondary amines with halogenated arenes. Forc-
ing reaction conditions are necessary with deactivated
arenes, whereas suitable electron poor arenes react
smoothly. The functionalization of threefold Boc-protect-
ed cyclen 1a18 by reaction with the Sanger reagent, 2,4-
dinitrofluorobenzene, has been reported by Kimura et al.19
We have applied the SNAr reaction of an activated arene
to the synthesis of arene-bridged biscyclen 4, which is
available by reaction of 1a with 1,3-difluoro-4,6-dini-
trobenzene (2) in good yield. However, subsequent varia-
tions of substituents and of the structure of the arene call
for a synthetic method, which is not restricted by the elec-
tronic nature of the arene reactant.
Buchwald,17,20–23 Hartwig16,24 and others25 have devel-
oped palladium-catalyzed procedures for N-arylation re-
Synthesis 2001, No. 12, 25 09 2001. Article Identifier:
1437-210X,E;2001,0,12,1818,1825,ftx,en;Z05201ss.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881

PAPER
N-Arylation of 1,4,7,10-Tetraazacyclododecanes
1819
nation as to why the functionalization of the secondary the formation of the hemiaminal of aldehyde 5e with
amino group is so difficult. In the depicted lowest energy amine 1a, which reacts, after deprotonation with an
conformer, determined from force field calculation,29 the arylpalladium species, to form an alkoxypalladium inter-
secondary amino moiety is buried inside the molecule mediate. The alkoxypalladium compound yields amide 8
leading to considerable steric hindrance in the substitution and a hydridopalladium species, which generates, after re-
reaction.
ductive elimination, an aromatic hydrocarbon. The reac-
tion of 1a with 2-bromopyridine (5f) gave acceptable
reaction conversions with better yields. The use of palla-
dium(II) acetate as palladium source and triphenylphos-
phine as ligand turned out to be the best conditions for this
reaction, which is in agreement with the findings of Witul-
ski et al. in coupling reactions with larger N,O-macrocy-
cles.27 For comparison, 5f was reacted with diethylamine
giving the substitution product 5g in nearly quantitative
yield. This again illustrates that difficulties in the coupling
reaction most likely arise from the structure of 1a.
Scheme 2 Palladium-catalyzed N-arylation of partially protected
cyclen with haloarenes; for reagents and conditions, see Table 1
Scheme 3 Palladium-catalyzed N-arylation of partially protected
cyclen with functionalized bromoarenes and bromopyridine; for
reagents and conditions, see Table 1
Figure Molecular model of the lowest energy conformer of 1a as
determined by force field methods
Several functionalized bromoarenes, such as 5c, 5d and 5e
were allowed to react with 1a under various conditions
(entries 15–21, Table 1 and Scheme 3) giving the corre-
sponding coupling products in low yields. The use of 730
or 1331 as a ligand, which was advantageous in recently re-
ported reactions, did not improve yield and conversion
significantly. In the reaction of 1a with 4-bromobenzalde-
hyde (5e) (entries 19–21), compound 8 was isolated as the
major product (Figure). We rationalize the formation of
the acylation product 8 by a palladium mediated direct ox-
idative transformation of the aldehyde to the amide, fol-
lowed by a reductive elimination of the arylhalide.
Yoshida et al. reported such amide formation under simi-
lar coupling conditions.32 The reaction was explained by
Scheme 4
Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York

1820
M. Subat, B. König
PAPER
Table 1 Coupling Conditions and Yields for Palladium-catalyzed N-Arylation Reactions
Entry Starting
Materials
Palladium
Source 5
mol%a
Ligand
7.5–10
mol%b
Solvent
Reaction Reaction Isolated
Yield Corrected
by Conversion
(%)
Temp
Time
(h)
Yield
(%)
(°C)
1
2
1b + 5a
1a + 5a
1a + 5a
1a + 5a
1a + 5a
1a + 5b
1a + 5b
1a + 5b
1a + 5b
1a + 5a
1a + 5b
Pd2dba3
BINAP
BINAP
BINAP
BINAP
BINAP
BINAP
DPPF
toluene
toluene
toluene
THF
80
80
80
66
80
80
80
80
80
80
80
48
48
n.c.c
8
n.c.
21
21
10
26
31
54
63
41
51
48
Pd2dba3
3
Pd2dba3
96
8
4
Pd2dba3
120
120
120
120
26
4
5
Pd(OAc)2
Pd2dba3
toluene
toluene
toluene
toluene
5b
4
6
7
7
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
20
11
12
17
18
8
DPPF
9
DPPF
27
10
11a
DPPF
toluene
toluene
120
120
Pd(OAc)2
5 mol%
DPPF
15 mol%
11b
1a + 5b
Pd(OAc)2
10 mol%
DPPF
15 mol%
toluene
80
120
19
47
12
13
14
15
16
17
18
19
1a + 5b
1a + 5a
1a + 5b
1a + 5c
1a + 5c
1a + 5c
1a + 5d
1a + 5e
Pd(OAc)2
Pd2dba3
DPPF
BINAP
DPPF
PPh3
DPPF
7
toluene + 18-crown-6d
THF
80
20
20
80
80
80
80
80
36
120
160
30
10
24
n.c.
n.c.
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
toluene + 18-crown-6d
toluene
n.c.
n.c.
15 (6c)
7 (6c)
16 (6c)
13 (6d)
26 (6c
20 (6c)
32 (6c)
20 (6d)
toluene
60
toluene
86
PPh3
PPh3
toluene
80
toluene
96
5 (6e)
25 (8)
9 (6e)
45 (8)
20
21
1a + 5e
1a + 5e
Pd(OAc)2
Pd(OAc)2
PPh3
toluene
toluene
80
80
39
96
6 (6e)
40 (8)
10 (6e)
67 (8)
DPPF
4 (6e)
15 (8)
8 (6e)
39 (8)
22
23
24
25
26
27
28
1a + 5f
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd2dba3
PPh3
7
toluene
toluene
toluene
toluene
toluene
toluene
toluene
80
80
80
80
80
80
80
65
96
55 (6f)
30 (6f)
46 (6g)
11 (6f)
22 (6f)
92 (5h)
98 (5g)
89 (6f)
40 (6f)
60 (6g)
35 (6f)
43 (6f)
92 (5h)
98 (5g)
1a + 5f
1c + 5f
PPh3
13
144
115
115
44
1a + 5f
1a + 5f
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
13
HNEt2 + 5b
HNEt2 + 5f
DPPF
PPh3
8
a The value corresponds to the amount of palladium added to the reaction mixture.
b 10 mol% for monodentate ligands and 7.5 mol% for bidentate ligands unless otherwise stated.
c No conversion.
d 1.4 Equiv of 18-crown-6 were added.
Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
N-Arylation of 1,4,7,10-Tetraazacyclododecanes
1821
Table 2 Coupling Conditions and Yields of Aryl- and Heteroaryl-bridged Cyclens Prepared
Entry
Starting
Materials
Palladium Source 5 Ligand 7.5–10
Solvent
toluene
toluene
toluene
toluene
toluene
Reaction Reaction Isolated Yield
Temp (°C) Time (h)
Yield Corrected
by Conversion
mol%
mol%
1
2
3
4
5
6
1a + 9a
1a + 9a
1a + 9a
1a + 9b
1a + 9c
1a + 9c
Pd(OAc)2
DPPF
80
80
80
80
80
80
40
120
86
3 (6a)
1 (11a)
7 (6a)
1 (11a)
Pd(OAc)2
Pd2dba3
DPPF
BINAP
DPPF
PPh3
4 (6a)
2 (11a)
5 (6a)
2 (11a)
5 (6a)
2 (11a)
9 (6a)
3 (11a)
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
40
8 (6a)
2 (11a)
12 (6a)
5 (11a)
62
54 (11b)
7 (12)
68 (11b)
7 (12)
PPh3
toluene
Cs2CO3
72
43 (10c)
11 (11b)
77 (10c)
20 (11b)
7
8
HNEt2 + 9c
Pd(OAc)2
Pd(OAc)2
PPh3
PPh3
toluene
toluene
80
80
29
38
86 (9d)
72 (12)
86 (9d)
78 (12)
1a + 9e
The reaction of 9c with diethylamine (entry 7) under stan-
dard conditions gave N,N-diethylaniline in good yield,
which illustrates the general feasibility of the reaction.
Scheme 5 Synthesis of arene-bridged bis-cyclens by palladium-cata-
lyzed N-arylation; for reagents and conditions, see Table 2
Scheme 6
Even though many optimized procedures for palladium
catalyzed N-aryl bond formation have been reported, the
functionalization of 1a by these methods turned out to be
very difficult. Steric hindrance caused by the protecting
groups presumably limits the accessibility of the reacting
secondary amine in the small macrocycle. Yields of aryla-
tion products and reaction conversion are generally very
low and in some cases unsatisfactory. The best results
were obtained with triphenylphosphine as monodentate
ligand and Pd(OAc)2 in toluene, which supports the earli-
er reported results with N,O-azacrownethers.27 Although
we could not find coupling conditions for 1a with simple
haloarenes that give satisfactory yields, the determined
conditions provide at least access to aryl-substituted cy-
clens in small amounts. Such compounds have recently
Twofold coupling reactions of 1a with 9a and 9b gave, as
expected from the reactions with 5a and 5b, aryl-bridged
cyclen 11a in only very small amounts (entries 1–4,
Table 2 and Scheme 4). With the more reactive 2,6-dibro-
mopyridine (9c) moderate, but preparative useful yields of
heteroaryl-bridged cyclen 11b could be isolated (entries 5,
6). Interestingly compound 12 was isolated from this re-
action as a minor product. Its formation most likely pro-
ceeds via palladium-catalyzed aryl-aryl coupling of 10c.33
This, reaction is successfully competing with the second
N-aryl coupling step leading to 11b, but it can be sup-
pressed by the use of Cs2CO3 as a weaker base (entry 6).
A selective synthesis of compound 12 is possible by cou-
pling of 1a with 9e giving 12 in 78% yield (Scheme 5).
Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York

1822
M. Subat, B. König
PAPER
Palladium-catalyzed Synthesis of N¢N-Aryl-bisazamacrocycles;
General Procedure B
received considerable interest for applications as
chemosensors,34 and N-aryl coupling is by far the most
convenient method for their preparation. Much better re-
sults were obtained in the SNAr reaction of 1a with 2 and
the palladium-catalyzed coupling reactions of 1a with py-
ridine derivatives 5f and 9c yielding arene- and heteroare-
ne-substituted cyclens under optimized conditions in
moderate to satisfactory amounts. Our results show that
the success of palladium-catalyzed N-arylation of protect-
ed azamacrocycles is structure dependent and requires
further optimization for reactions with the sterically de-
manding amine 1a. However, although the method is still
limited it provides access to some derivatives of so far un-
Into a Schlenk tube were added the protected azamacrocycle (2
mmol), the aryl halide (1 mmol) and sodium t-butoxide or caesium
carbonate (2.8 mmol) as base. To this mixture a phosphine ligand
(0.20 mmol in case of monodentate ligands; 0.15 mmol in case of
bidentate ligands) and a palladium source (0.05 mmol for
tris(dibenzylideneacetone)dipalladium(0); 0.10 for palladium ace-
tate) were added. The solid materials were suspended in toluene (4–
5 mL). The tube was sealed, the mixture was degassed by three
freeze, pump, thaw cycles and heated to 80 °C. The reaction mix-
ture was stirred for 40–120 h, cooled to r.t., diluted with CH2Cl2 (50
mL), filtered through Celite, and concentrated in vacuum. The
crude product was purified by CC on silica gel (PE–EtOAc, 4:1).
After isolation of the product, the eluent was changed to PE–EtOAc
known arene-bridged cyclens, which are of interest for (2:3) to recover unreacted azamacrocycle. Yields are given as iso-
lated yield and corrected by conversion (cbc).
use as ionophors in chemosensors or artificial receptors in
molecular recognition.
1,3-Bis(1,4,7-tris[t-butyloxycarbonyl]-1,4,7,10-tetraazacyclodo-
decane)-2,4-dinitrobenzene (4)
All reactions were carried out in oven-dried glassware under a N2
atm using standard Schlenk-technique unless otherwise stated. Ele-
mental analyses were performed at Microanalytical Laboratories,
University of Regensburg. Toluene was distilled under N2 from
molten Na. THF was distilled under N2 from molten K. The crown
ether 18C6 and all aryl halides were purchased from commercial
sources and were used without further purification. Sodium t-butox-
ide and caesium carbonate were purchased from Aldrich Chemical
Co., stored under N2, and weighed out in the air. The protected
azamacrocycles were prepared as previously described in litera-
ture.15,35,36 PPh3 was purchased form Merck Co. and was purified by
crystallization form EtOH and dried in high vacuum. Palladium ac-
etate, Pd2(dba)3 and other phosphine ligands were purchased from
Strem Chemical Co. and used without further purification. Prepara-
tive flash column chromatography (CC) was performed using Mer-
ck Flash Silica Gel (70–230 mesh). Yields refer to isolated yields
and conversion corrected yields (based on isolated and unreacted
starting material) of compounds estimated to be ≥95% by 1H NMR
and elemental analysis or high resolution mass-spectroscopy (for
new compounds). All products were characterized from 1H NMR,
13C NMR, IR, UV/Vis and mass spectra. NMR spectra were record-
ed at 250 and 400 MHz (1H) and at 63 and 100 MHz (13C) in CDCl3
solutions. The multiplicity of the 13C signals was determined with
the DEPT technique and quoted as: (+) for CH3 or CH, (–) for CH2
or for quaternary carbons (Cquat). Mps were taken on a hot-plate mi-
croscope apparatus and are uncorrected. Petroleum ether (PE) with
a boiling range of 60–70 °C was used.
A mixture of 1,3-difluoro-4,6-dinitrobenzene (2, 0.26 g, 1.27
mmol) and 1,4,7-tris(t-butyloxycarbonyl)-1,4,7,10-tetraazacy-
clododecane (1, 1.20 g, 2.54 mmol) was dissolved in CH3CN (30
mL). The solution was stirred in the presence of NaHCO3 (0.45 g,
5.33 mmol) at 80 °C under N2 for 60 h, insoluble inorganic salts
were filtered off, the solvent was removed in vacuo, and the residue
was subjected to CC on silica gel (PE–EtOAc, 1:1).
Yield: 1.17 g (83%); yellow solid.
Rf = 0.22 (PE–EtOAc, 1:1).
Mp 105 °C.
UV (MeCN): lmax, nm (log e) = 229 (4.206), 365 (4.239).
IR (KBr): 2974, 2932, 1703, 1561, 1366, 1164 cm–1.
1H NMR (250 MHz): d = 1.41 (s, 36 H), 1.44 (s, 18 H), 3.39–3.55
(m, 32 H), 6.59 (s, 1 H), 8.44 (s, 1 H).
13C NMR (63 MHz): d = 28.4 (+), 28.5 (+), 47.6 (–), 49.5 (–), 50.5
(–), 51.4 (–), 80.3 (Cquat), 80.4 (Cquat), 106.9 (+), 129.0 (+), 130.9
(Cquat), 149.1 (Cquat), 156.4 (Cquat), 156.6 (Cquat).
MS (ESI, 70 eV): m/z (%) = 1109 (100, MH+), 1009 (18, MH+–
BOC).
Anal. Calcd for C52H88N10O16: C, 56.30; H, 8.00; N, 12.63. Found:
C, 55.85; H, 7.94; N, 11.98.
1-Fluoro-3-(1,4,7-tris[t-butyloxycarbonyl]-1,4,7,10-tetraaza-
cyclododecane)-2,4-dinitrobenzene (3)
Compound 3 was isolated as a by-product in the reaction of 1 with 2.
Palladium-catalyzed Synthesis of N-Aryl-azamacrocycles;
General Procedure A
Yield: 0.10 g (12%); yellow solid.
Rf = 0.48 (PE–EtOAc, 1:1).
A Schlenk tube was charged with 5 mol% of a palladium source
(0.025 mmol for tris(dibenzylideneacetone)dipalladium(0); 0.050
mmol for palladium acetate), a phosphine ligand (0.10 mmol in case
of monodentate ligands; 0.075 mmol in case of bidentate ligands),
sodium t-butoxide (1.4 mmol) and toluene (2 mL). To this mixture
the protected azamacrocycle (0.11 mmol) and the aryl halide (0.10
mmol) was added, the tube was sealed, the reaction mixture was de-
gassed by three freeze, pump, thaw cycles and heated to 80 °C. The
mixture was stirred for 26–120 h, cooled to r.t., diluted with CH2Cl2
(40 mL), filtered through Celite, and concentrated in vacuum. The
crude product was purified by CC on silica gel (PE–EtOAc, 4:1).
After isolation of the product, the eluent was changed to PE–EtOAc
(2:3) to recover unreacted starting material. Yields are given as iso-
lated yield and corrected by conversion (cbc).
Mp 86 °C.
UV (MeCN): lmax, nm (log e) = 228 (4.045), 368 (4.179).
IR (KBr): 2976, 2931, 1698, 1580, 1367, 1161 cm–1.
1H NMR (250 MHz): d = 1.46 (s, 9 H), 1.48 (s, 18 H), 3.42–3.50 (m,
16 H), 6.86 (d, 1 H, 3J = 13.9 Hz). 8.55 (d, 1 H, 4J = 7.9 Hz).
13C NMR (63 MHz): d = 28.5 (+), 28.5 (+), 47.7 (–), 49.6 (–), 50.5
(–), 52.4 (–), 80.6 (Cquat), 81.0 (Cquat), 105.8 (+, d, 2JC,F = 26.6 Hz),
126.4 (Cquat, d, 4JC,F = 8.9 Hz), 126.8 (Cquat), 133.7 (+), 148.8 (Cquat
,
3
d, JC,F = 11.8 Hz), 156.2 (Cquat), 157.0 (Cquat), 158.3 (Cquat, d,
1JC,F = 269.0 Hz).
MS (ESI, 70 eV): m/z (%) = 657 (95, MH+), 557 (100, MH+–BOC).
HRMS: m/z calcd for C29H45FN6O10 [MH]+: 657.3259. Found:
657.3259 1.5 ppm.
Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
N-Arylation of 1,4,7,10-Tetraazacyclododecanes
1823
2-Diethylaminopyridine (5g)
1-(4-Nitrobenezene)-4,7,10-tris(t-butyloxycarbonyl)-1,4,7,10-
tetraazacyclododecane (6c)
A mixture of palladium acetate (14.2 mg, 2 mol%), DPPF (52.2 mg,
3 mol%), sodium t-butoxide (395 mg, 4.1 mmol), 2-bromopyridine
(5f) (500 mg, 3.2 mmol) and diethylamine (254 mg, 3.5 mmol) were
placed into a Schlenk tube and suspended in toluene (2 mL). The
mixture was degassed and heated for 8 h at 80 °C, cooled to r.t., di-
luted with CH2Cl2 (20 mL), and filtered through Celite. The filtrate
was concentrated in vacuum and purified by CC (PE–EtOAc, 9:1)
to yield 464 mg (98%) 5g as a colourless liquid.
Azamacrocycle 1a (500 mg, 1.06 mmol) and aryl halide 5c were al-
lowed to react according to the general procedure A using Pd(OAc)2
and PPh3 as a catalyst. The reaction mixture was heated to 80 °C for
30 h. Compound 6c was isolated as a yellow solid; yield: 98 mg
(15%, 26%cbc).
Rf = 0.37 (PE–EtOAc, 1:1).
Mp 108 °C.
Rf = 0.64 (PE–EtOAc, 6:1).
UV (MeCN): lmax, nm (log e) = 232 (4.053), 396 (4.432).
IR (KBr): 2976, 2933, 1695, 1597, 1319, 778 cm–1.
1H NMR (400 MHz): d = 1.38 (s, 18 H), 1.45 (s, 9 H), 3.36–3.45 (m,
1H NMR (250 MHz): d = 1.18 (t, 6 H, J = 7.1 Hz), 3.51 (q, 4 H,
3
3J = 7.1 Hz), 6.43–6.49 (m, 2 H), 7.36–7.43 (m, 1 H), 8.14 (dd, 1 H,
3J = 5.9 Hz, 4J = 1.9 Hz).
3
13C NMR (63 MHz): d = 12.9 (+), 42.4 (–), 105.5 (+), 110.8 (+),
137.0 (+), 148.1 (+), 157.5 (Cquat).
12 H), 3.44 (br s, 4 H), 6.61 (d, 2 H, J = 9.4 Hz), 8.08 (d, 2 H,
4J = 9.4 Hz).
13C NMR (100 MHz): d = 28.44 (+), 28.5 (+), 49.0 (–), 50.0 (–),
50.2 (–), 53.2 (–), 110.7 (+), 126.3 (+), 137.4 (Cquat), 152.7 (Cquat),
156.2 (Cquat), 157.3 (Cquat).
MS (ESI, 70 eV): m/z (%) = 594 (48, MH+), 578 (100).
HRMS: m/z calcd. for C29H47N5O8 [M]+: 593.3424. Found:
2,6-Bis(diethylamino)pyridine (9d)
A mixture of palladium acetate (13.5 mg, 1.3 mol%), DPPF (51.4
mg, 2 mol%), sodium t-butoxide (528 mg, 5.5 mmol), 2,6-dibro-
mopyridine (9c, 500 mg, 2.1 mmol) and diethylamine (338 mg, 4.64
mmol) were placed into a Schlenk tube and suspended in toluene (3
mL). The mixture was degassed and heated for 29 h at 80 °C, cooled
to r.t., taken up in CH2Cl2 (20 mL), and filtered through Celite. The
filtrate was concentrated in vacuum and purified by CC (PE–
EtOAc, 19:1) to yield 402 mg (86%) of 9d as a colorless liquid.
593.3428 0.4 ppm.
1-(4-[1,3]Dioxalan-2-yl-phenyl)-1,4,7,10-tetraazacyclododeca-
ne (6d)
Azamacrocycle 1a (400 mg, 0.85 mmol) and aryl halide 5d were re-
acted according to the general procedure A using Pd(OAc)2 and
PPh3 as a catalyst. The reaction mixture was heated to 80 °C for 80
h. Compound 6d was isolated as a pale yellow solid; yield: 71 mg
(13%, 20%cbc).
Rf = 0.72 (PE–EtOAc, 6:1).
1H NMR (250 MHz): d = 1.16 (t, 12 H, 3J = 7.0 Hz), 3.46 (q, 8 H,
3J = 7.0 Hz), 5.71 (d, 2 H, 3J = 8 Hz), 7.19–7.28 (m, 1 H).
N,N-Diethylaminoaniline (5h)
Rf = 0.42 (PE–EtOAc, 1:1).
A mixture of palladium acetate (35.6 mg, 5 mol%), DPPF (132 mg,
7.5 mol%), sodium t-butoxide (397 mg, 4.1 mmol), 5b (500 mg, 3.2
mmol) and diethylamine (255 mg, 3.5 mmol) was added in a
Schlenk tube and suspended with toluene (3 mL). The reaction mix-
ture was degassed and heated for 64 h at 80 °C, diluted with CH2Cl2
(20 mL), and filtered through Celite. The filtrate was concentrated
in vacuum and purified by CC (PE–EtOAc, 19:1) to yield 434 mg
(92%) of 5h.
Mp 78 °C.
UV (MeCN): lmax, nm (log e) = 263 (4.405), 338 (3.854).
IR (KBr): 2978, 2933, 1694, 1169, 777 cm–1.
1H NMR (400 MHz): d = 1.45 (s, 18 H), 1.47 (s, 9 H), 3.24–3.52 (m,
16 H), 3.98–4.03 (m, 2 H), 4.13–4.17 (m, 2 H), 5.71 (s, 1 H), 6.71
(d, 2 H, 3J = 8.6 Hz), 7.33 (d, 2 H, 3J = 8.6 Hz).
13C NMR (100 MHz): d = 28.5 (+), 28.6 (+), 49.2 (–), 50.2 (–), 50.8
(–), 53.1 (–), 65.2 (–), 79.7 (Cquat), 80.0 (Cquat), 104.0 (+), 114,5 (+),
127.0 (Cquat), 127.7 (+), 150.1 (Cquat), 156.3 (Cquat).
Rf = 0.81 (PE–EtOAc, 10:1).
1H NMR (250 MHz): d = 1.15 (t, 6 H, J = 7.0 Hz), 3.34 (q, 4 H,
3
3J = 7.0 Hz), 6.61–6.71 (m, 3 H), 7.15–7.22 (m, 2 H).
MS (ESI, 70 eV): m/z (%) = 623 (82, MH+), 591 (100).
1-Phenyl-4,7,10-tris(t-butyloxycarbonyl)-1,4,7,10-tetraaza-
cyclododecane (6a)
HRMS: m/z calcd. for C32H52N4O8 [MH]+: 621.3863. Found:
621.3869 1.7 ppm.
Azamacrocycle 1a (300 mg, 0.64 mmol) and aryl halide 5b were re-
acted according to the general procedure A using Pd(OAc)2 and
DPPF as a catalyst. The reaction mixture was heated to 80 °C for
120 h. Compound 6a [71 mg (20%, 54%cbc)] was isolated as a white
solid.
1-(N-Phenylcarbonyl)-4,7,10-tris(t-butyloxycarbonyl)-1,4,7,10-
tetraazacyclododecane (8) and 4-(1,4,7,10-Tetraazacyclododec-
1-yl)-benzaldehyde (6e)
Azamacrocycle 1a (300 mg, 0.64 mmol) and aryl halide 5e were re-
acted at 80 °C for 39 h according to the general procedure A using
Pd(OAc)2 and PPh3 as a catalyst.
Rf = 0.61 (PE–EtOAc, 1:1).
Mp 62 °C.
UV (MeCN): lmax, nm (log e) = 218 (3.955), 256 (4.078), 292
Compound 6e
(3.453).
Isolated as minor product; yield: 22 mg (6%, 10% cbc); pale yellow
solid.
IR (KBr): 2977, 2931, 1692, 1167, 776, 753 cm–1.
1H NMR (400 MHz): d = 1.46 (s, 9 H), 1.48 (s, 18 H), 3.37–3.51 (m,
Rf = 0.53 (PE–EtOAc, 1:1).
16 H), 6.72–6.79 (m, 3 H), 7.22 (dd, 2 H, 3J = 7.4 Hz, 4J = 1.0 Hz).
Mp 63 °C.
13C NMR (100 MHz): d = 28.4 (+), 28.5 (+), 49.9 (–), 50.1 (–), 51.9,
79.9 (Cquat), 129.2 (+), 137.4 (Cquat), 156.4 (Cquat).
MS (EI, 70 eV): m/z (%) = 548 (94, M+), 57 (100).
HRMS: m/z calcd. for C29H48N4O6 [M]+: 548.3573. Found:
UV (MeCN): lmax, nm (log e) = 342 (3.075).
IR (KBr): 2977, 2963, 1694, 1164, 832 cm–1.
1H NMR (250 MHz): d = 1.42 (s, 9 H), 1.47 (s, 18 H), 3.37–3.86 (m,
16 H), 6.71 (d, 2 H, 3J = 8.9 Hz), 7.72 (d, 2 H, 3J = 8.9 Hz), 9.74 (s,
1 H).
548.3576 0.4 ppm.
Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York

1824
M. Subat, B. König
PAPER
13C NMR (100 MHz): d = 28.4 (+), 29.0 (+), 49.2 (–), 50.2 (–), 53.0
(–), 80.4 (Cquat), 111.6 (+), 122.5 (Cquat), 125.9 (Cquat), 132.1 (+),
156.3 (Cquat), 190.3 (+).
MS (ESI, 70 eV): m/z (%) = 577 (53, MH+), 599 (100, M+Na+).
HRMS: m/z calcd. for C30H48N4O7 [M]+: 576.3523. Found:
13C NMR (100 MHz): d = 21.5 (+), 21.6 (+), 51.4 (–), 51.7 (–), 51.8
(–), 52.3 (–), 107.6 (+), 112.5 (+), 127.7 (+), 128.0 (+), 129.8 (+),
129.9 (+), 133.2 (Cquat), 133.9 (Cquat), 137.7 (+), 143.9 (Cquat), 144.1
(Cquat), 147.4 (+), 158.3 (Cquat).
MS (ESI, 70 eV): m/z (%) = 712 (100, MH+).
HRMS: m/z calcd. for C34H41N5O6S3 [M]+: 711.2218. Found:
576.3516 0.6 ppm.
711.2214 0.6 ppm.
Compound 8
Isolated as the major product; yield: 151 mg (40%, 67%cbc); white
solid.
1,3-Bis(1,4,7-tris[t-butyloxycarbonyl]-1,4,7,10-
tetraazacyclododecane)-benzene (11a)
Protected azamacrocycle 1a (2 equiv, 700mg, 1.48 mmol) and aryl
halide 9b were reacted according to the general procedure A at
80 °C for 40 h with sodium t-butoxide as base and Pd(OAc)2/DPPF
as a catalyst. The major product was the dehydrohalogenation com-
pound 6a; yield: 32 mg (8%, 12%cbc); Rf = 0.61 (PE–EtOAc, 1:1).
Compound 11a was isolated as colorless, viscous oil; yield: 15 mg
(2%, 5%cbc).
Rf = 0.39 (PE–EtOAc, 1:1).
Mp 71 °C.
UV (MeCN): lmax, nm (log e) = 338 (3.162).
IR (KBr): 2978, 2934, 1696, 1641, 1166, 733 cm–1.
1H NMR (400 MHz): d = 1.30 (s, 9 H), 1.47 (s, 9 H), 1.50 (s, 9 H),
3.31–3.63 (m, 16 H), 7.34–7.41 (m, 5 H).
13C NMR (100 MHz): d = 28.3 (+), 28.4 (+), 48.1 (–), 49.0 (–), 49.3
(–), 49.7 (–), 49.9 (–), 50.3 (–), 50.7 (–), 51.3 (–), 80.0 (Cquat), 80.3
(Cquat), 80.4 (Cquat), 126.3 (+), 128.5 (+), 129.3 (+), 136.6 (Cquat),
155.5 (Cquat), 156.8 (Cquat), 157.0 (Cquat), 172.4 (Cquat).
Rf = 0.47 (PE–EtOAc, 1:1).
UV (MeCN): lmax, nm (log e) = 258 (3.879), 283 (3.458).
IR (KBr): n = 2976, 2931, 1695, 1165, 782 cm–1.
1H NMR (400 MHz): d = 1.45 (s, 36 H), 1.47 (s, 18 H), 3.38–3.45
3
MS (ESI, 70 eV): m/z (%) = 577 (25, MH+), 599 (100, M+Na+).
HRMS: m/z calcd. for C30H48N4O7 [M]+: 576.3523. Found:
(m, 32 H), 6.03 (s, 1 H), 6.17 (d, 2 H, J = 8.1 Hz), 7.07 (t, 1 H,
3J = 8.2 Hz).
13C NMR (100 MHz): d = 28.4 (+), 28.5 (+), 28.6 (+), 50.2 (–), 50.7
(–), 79.9 (Cquat), 80.0 (Cquat), 129.3 (+), 130.0 (+), 137.4 (Cquat),
156.3 (Cquat).
576.3513 0.4 ppm.
1-(2-Pyridinyl)-4,7,10-tris(t-butyloxycarbonyl)-1,4,7,10-
tetraazacyclododecane (6f)
MS (EI, 70 eV): m/z (%) = 1018 (100, M+), 57 (72).
Azamacrocycle 1a (400 mg, 0.85 mmol) and bromopyridine 5f
were reacted at 80 °C for 65 h according to the general procedure A
using Pd(OAc)2 and PPh3 as a catalyst. Compound 6f was isolated
as white solid; yield: 257 mg (55%, 89%cbc).
The m/z of the molecular ion is too high to obtain HRMS with our
instrumentation. However, the calculated and measured isotope in-
tensity patterns of the M+ peak are identical (1018 / 100%; 1019 /
62%; 1020 / 22%; 1022 / 10%).
Rf = 0.48 (PE–EtOAc, 1:1).
1,3-Bis(1,4,7-tris[t-butyloxycarbonyl]-1,4,7,10-
tetraazacyclododecane)-pyridine (11b)
Mp 58 °C.
UV (MeCN): lmax, nm (log e) = 252 (4.179), 308 (3.514).
IR (KBr): 2977, 2933, 1693, 1168, 776 cm–1.
1H NMR (400 MHz): d = 1.45 (s, 27 H), 3.21 (br s, 4 H), 3.42–3.51
(m, 8 H), 3.67 (br s, 4 H), 6.53–6.59 (m, 2 H), 7.36–7.43 (m, 1 H),
8.13 (dd, 1 H, 3J = 4.9 Hz, 4J = 1.2 Hz).
13C NMR (100 MHz): d = 28.4 (+), 28.5 (+), 50.6 (–), 51.8 (–), 79.9
(Cquat), 107.8 (+), 112.5 (+), 137.1 (+), 147.7 (+), 156.5 (Cquat),
159.3 (Cquat).
Protected azamacrocycle 1a (2 equiv, 1 g, 2.12 mmol) and bro-
mopyridine 9c were reacted according to the general procedure B at
80 °C for 62 h with sodium t-butoxide as base and Pd(OAc)2 and
PPh3 as a catalyst. Compound 12 was isolated as a side product;
yield: 81 mg (7%, 8%cbc), white solid; Rf = 0.19 (PE–EtOAc, 7:3).
Compound 11b was isolated as the major product; yield: 587 mg
(54%, 68%cbc); white solid.
Rf = 0.47 (PE–EtOAc, 1:1).
Mp 107 °C.
MS (ESI, 70 eV): m/z (%) = 550 (100, MH+).
UV (MeCN): lmax, nm (log e) = 225 (4.383), 260 (4.031), 320
Anal. Calcd for C28H47N5O6: C, 61.18; H, 8.62; N, 12.74. Found: C,
61.11; H, 8.59; N, 12.01.
(4.078).
IR (KBr): 2978, 2934, 1695, 1167, 777 cm–1.
1-Pyridine-4,7,10-tritosyl-1,4,7,10-tetraazacyclododecane (6g)
Azamacrocycle 1c (100 mg, 0.16 mmol) and bromopyridine 5f were
allowed to react according to the general procedure A at 80 °C for
144 h using Pd(OAc)2 and PPh3 as a catalyst. Compound 6g was
isolated as white solid; yield: 52 mg (46%, 60%cbc).
1H NMR (400 MHz): d = 1.45 (s, 54 H), 3.27–3.59 (m, 32 H), 5.92
(d, 2 H, 3J = 8.1 Hz), 7.23 (t, 1 H, 3J = 8.1 Hz).
13C NMR (100 MHz): d = 28.5 (+), 28.6 (+), 49.2 (–), 50.2 (–), 51.8
(–), 79.8 (Cquat), 96.1 (+), 138.6 (+), 156.4 (Cquat), 158.3 (Cquat).
MS (ESI, 70 eV): m/z (%) = 1020 (100, MH+), 1042 (37, M+Na+).
Rf = 0.31 (PE–EtOAc, 1:1).
Anal. Calcd for C51H89N9O12: C, 60.04; H, 8.79; N, 12.35. Found:
C, 59.83; H, 8.79; N, 11.86.
Mp 117 °C.
UV (MeCN): lmax, nm (log e) = 231 (4.688), 308 (3.631).
IR (KBr): 2928, 2861, 1340, 1161, 693, 550 cm–1
1H NMR (400 MHz): d = 2.43 (s, 6 H), 2.45 (s, 3H), 3.18 (br s, 4 H),
1-(3-Bromo-2-pyridinyl)-4,7,10-tris(t-butyloxycarbonyl)-
1,4,7,10-tetraazacyclododecane (10c)
Following the general procedure B, protected azamacrocycle 1a (2
equiv, 500 mg, 1.06 mmol) and bromopyridine 9c were reacted at
80 °C for 72 h with caesium carbonate as base and Pd(OAc)2 and
PPh3 as a catalyst. Compound 11b was isolated as a minor product;
yield: 61 mg (11%, 20%cbc), white solid; Rf = 0.47 (PE–EtOAc,
3
3.40–3.47 (m, 8 H), 4.00 (br s, 4 H), 6.57 (dd, 1 H, J = 6.8 Hz,
4J = 1.6 Hz), 6.84 (d, 1 H, 3J = 8.6 Hz), 7.32 (d, 6 H, 3J = 8.2 Hz),
3
4
7.47–7.53 (m, 1 H), 7.67 (dd, 6 H, J = 8.2 Hz, J = 1.7 Hz), 8.09
(dd, 1 H, 3J = 4.9 Hz, 4J = 1.4 Hz).
Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
N-Arylation of 1,4,7,10-Tetraazacyclododecanes
1825
1:1). Compound 10c was isolated as the major product; yield: 145
(4) Fabbrizzi, L.; Licchelli, M.; Pallavicini, P.; Perotti, A.;
Taglietti, A.; Sacchi, D. Chem.–Eur.J. 1996, 2, 75.
(5) Gaspar, M.; Grazina, R.; Bodor, A.; Farkas, E.; Santos, M.
A. J. Chem. Soc., Dalton Trans. 1999, 799.
(6) Lecomte, C.; Dahaoui-Gindrey, V.; Chollet, H.; Gros, C.;
Mishra, A. K.; Barbette, F.; Pullumbi, P.; Guilard, R. Inorg.
Chem. 1997, 36, 3827.
(7) Luckay, R. C.; Hancock, R. D. J. Chem. Soc., Dalton Trans.
1991, 1491.
(8) Kimura, E.; Kikuta, E. Prog. React. Kinet. 2000, 25, 1.
(9) Fujioka, H.; Koike, T.; Yamada, N.; Kimura, E.
Heterocycles 1996, 42, 775.
mg (43%, 77%cbc); white solid.
Rf = 0.64 (PE–EtOAc, 1:1).
Mp 74 °C.
UV (MeCN): lmax, nm (log Œ) = 258 (4.203), 315 (3.736).
IR (KBr): 2978, 2932, 1695, 1169, 776 cm–1.
1H NMR (250 MHz): d = 1.41 (s, 18 H), 1.43 (s, 9 H), 3.24–3.62 (m,
16 H), 6.44 (d, 1 H, 3J = 8.3 Hz), 6.67 (d, 1 H, 3J = 7.4 Hz), 7.19 (dd,
1 H, 3J = 8.3 Hz, 3J = 7.3 Hz).
13C NMR (63 MHz): d = 28.4 (+), 28.5 (+), 49.9 (–), 50.3 (–), 51.9
(–), 80.0 (Cquat), 105.1 (+), 115.1 (+), 139.1 (+), 140.0 (Cquat), 156.5
(Cquat), 158.8 (Cquat).
(10) Koike, T.; Takashige, M.; Kimura, E.; Fujioka, H.; Shiro, M.
Chem.–Eur. J. 1996, 2, 617.
(11) Aoki, S.; Kimura, E. J. Am. Chem. Soc. 2000, 122, 4542.
(12) Kimura, E.; Koike, T. Chem. Commun. 1998, 1495.
(13) König, B.; Pelka, M.; Klein, M.; Dix, I.; Jones, P. G.; Lex, J.
J. Inclusion Phenom.; 2000, 37, 39, and cited references.
(14) Denat, F.; Brandes, S.; Guilard, R. Synlett 2000, 561.
(15) Filali, A.; Yaouanc, J.-J.; Handel, H. Angew. Chem., Int. Ed.
Engl. 1991, 30, 560.
(16) Hartwig, J. F. Acc. Chem. Res. 1998, 31, 852.
(17) Singer, R. A.; Sadighi, J. P.; Buchwald, S. L. J. Am. Chem.
Soc. 1998, 120, 213.
(18) Brandes, S.; Gros, C.; Denat, F.; Pullumbi, P.; Guilard, R.
Bull. Soc. Chim. Fr. 1996, 133, 65.
(19) Koike, T.; Gotoh, T.; Aoki, S.; Kimura, E.; Shiro, M. Inorg.
Chim. Acta 1998, 270, 424.
(20) Wolfe, J. P.; Buchwald, S. L. J. Org. Chem. 2000, 65, 1144.
(21) Wolfe, J. P.; Sadighi, H. T.; Yin, J.; Buchwald, S. L. J. Org.
Chem. 2000, 65, 1158.
(22) Wolfe, J. P.; Marcoux, J.-F.; Buchwald, S. L. Acc. Chem.
Res. 1998, 31, 805.
MS (ESI, 70 eV): m/z (%) = 630 (100, MH+, 81Br), 628 (94, MH+,
79Br), 550 (80, M+–Br).
Anal. Calcd for C28H46N5O6Br: C, 53.71; H, 7.38; N, 11.14. Found:
C, 53.69; H, 7.30; N, 10.80.
1,3-Bis(1,4,7-tris[t-butyloxycarbonyl]-1,4,7,10-
tetraazacyclododecane)-bipyridine (12)
According to the general procedure B, 1a (2 equiv, 500 mg, 1.06
mmol) and dibromobipyridine 9e were reacted at 80 °C for 38 h
with sodium t-butoxide as base and Pd(OAc)2 and PPh3 as a cata-
lyst. Compound 12 was isolated as a white solid; yield: 419 mg
(72%, 78%cbc).
Rf = 0.19 (PE–EtOAc, 7:3).
Mp 109 °C.
UV (MeCN): lmax, nm (log e) = 222 (4.726), 267 (4.536), 352
(4.306).
IR (KBr): 2978, 2933, 1695, 1578, 1169, 782 cm–1.
1H NMR (400 MHz): d = 1.45 (s, 54 H), 3.22–3.74 (m, 32 H), 6.59
(d, 2 H, 3J = 8.2 Hz), 7.52 (t, 2 H, 3J = 7.8 Hz), 7.65 (d, 2 H, 3J = 7.3
Hz).
(23) Old, D. W.; Harris, M. C.; Buchwald, S. L. Org. Lett. 2000,
2, 1403.
(24) Mann, G.; Hartwig, J. F.; Driver, M. S.; Fernández-Rivas, C.
J. Am. Chem. Soc. 1998, 120, 827.
(25) Lam, P. Y. S.; Deudon, S.; Averill, K. M.; Li, R.; He, M. Y.;
DeShong, P.; Clark, C. G. J. Am. Chem. Soc. 2000, 122,
7600.
(26) Zhang, X.-X.; Buchwald, S. L. J. Org. Chem. 2000, 65,
8027.
13C NMR (100 MHz): d = 28.5 (+), 28.6 (+), 50.3 (–), 50.7 (–), 52.2
(–), 79.8 (Cquat), 79.9 (Cquat), 107.6 (+), 109.6 (+), 137.9 (+), 154.5
(Cquat), 156.5 (Cquat), 158.6 (Cquat).
MS (ESI, 70 eV): m/z (%) = 1097 (100, MH+), 1119 (15, M+Na+).
(27) Witulski, B. Synlett 1999, 1223.
Anal. Calcd for C56H92N10O12: C, 61.29; H, 8.45; N, 12.76. Found:
C, 61.63; H, 8.53; N, 12.18.
(28) Wolfe, J. P.; Buchwald, S. L. J. Org. Chem. 1997, 62, 6066.
(29) The calculation was performed with the modelling software
SPARTAN using the MMFF force field and a conformer
search algorithm.
(30) Wolfe, J. P.; Buchwald, S. L. Angew. Chem. Int. Ed. 1999,
38, 2413.
Acknowledgement
We thank DSM, Regensburg and Schering AG, Berlin for donations
of cyclen.
(31) Zhang, X.-X.; Buchwald, S. L. J. Org. Chem. 2000, 65,
8027.
(32) Tamaru, Y.; Yamada, Y.; Yoshida, Z. Synthesis 1983, 474.
(33) Hatanaka, Y.; Goda, K.; Okahara, Y. Tetrahedron 1994, 50,
8301.
(34) Hirano, T.; Kikuchi, K.; Urano, Y.; Higuchi, T.; Nagano, T.
Angew. Chem. Int. Ed. 2000, 39, 1052.
(35) Prasad, J. S.; Okuniewicz, F. J.; Delaney, E. J.; Dischino, D.
D. J. Chem. Soc., Perkin Trans. 1 1991, 3329.
(36) Dumont, A.; Jacques, V.; Qixiu, P.; Desreux, J. F.
Tetrahedron Lett. 1994, 35, 3707.
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Synthesis 2001, No. 12, 1818–1825 ISSN 0039-7881 © Thieme Stuttgart · New York