Highly fluorescent heterocycles based on pyrazino fused 1,4,5,8-tetraazafulvalenes

Article abstract of DOI:10.3987/com-03-9842

Some new pyrazino-fused 1,4,5,8-tetraazafulvalenes of type (3-5) were synthesized and their structures were confirmed by IR, UV-VIS, ¹H NMR spectra and elemental analysis. The X-Ray crystal structure analysis of a single crystal of derivative (

Full text of DOI:10.3987/com-03-9842

HETEROCYCLES, Vol. 60, No. 11, 2003, pp. 2457 - 2470
Received, 30th June, 2003, Accepted, 10th September, 2003, Published online, 16th September, 2003
HIGHLY FLUORESCENT HETEROCYCLES BASED ON PYRAZINO
FUSED 1,4,5,8-TETRAAZAFULVALENES
Christian Käpplingera, Rainer Beckerta,*, Jan Kocib, Gabriela Braunerovab,
Karel Waisserb, and Helmar Görlsc
a
Institute of Organic and Macromolecular Chemistry, Friedrich Schiller
University, D-07743 Jena Lessingstr. 8, Germany, E mail: C6bera@uni-jena.de
b
Pharmaceutical Department, Charles University, CZ 50005 Hradec Kralove,
Heyrovskeho 1203, Czech Republic
c Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University, D-
07743 Jena August-Bebelstr. 2, Germany
Abstract - Some new pyrazino-fused 1,4,5,8-tetraazafulvalenes of type (3-5) were
synthesized and their structures were confirmed by IR, UV-VIS, 1H NMR spectra
and elemental analysis. The X-Ray crystal structure analysis of a single crystal of
derivative (3c) revealed a nearly ideal planarized heterofulvalene subunit. The
new prepared tricyclic tetraazafulvalenes of type (3) show strong red fluorescence
at 605 nm.
Substitution of the electron donating sulfur atoms in well-studied and for material science important
tetrathiafulvalenes by aza nitrogen atoms leads to a new class of electronically inverted (electron
acceptor) heterofulvalenes, namely the 1,4,5,8-tetraazafulvalenes (1). In contrast to the tetrathiafulvalenes
1
there exists only a few data for corresponding aza derivatives. In order to remedy this deficiency, we
have developed numerous new syntheses for obtaining 1,4,5,8-tetraazafulvalenes (1) as well as their
2-5
vinylogous derivatives.
All new obtained tetraazafulvalenes are redox active chromophoric systems
and could possibly be quite interesting for the development of new functional dyes. In addition, various
2
3
2,3,6
derivatizations such as alkylations, acylations and ring closure reactions
of the four secondary
amino groups present in 1 have been studied. On the other hand, we have demonstrated that aromatic

halogen atoms can be replaced by different amines under the conditions of the Hartwig-Buchwald
7
reaction. Finally, we could extent the palette of functionalized tetraazafulvalenes by replacing the
aromatic halogen atoms with carbon-carbon double bond systems (Heck reaction) as well as with
numerous acetylenes under Sonogashira conditions. 8
6
Recently, we published a short and efficient synthesis of pyrazino-fused tetraazafulvalenes. Their
UV/VIS spectra revealed a longest wavelength absorption at 658 nm (log ε = 4.9) which means a
bathochromic shift of about 140 nm as compared to the starting material. Despite of the high degree of
planarization in that fused pyrazines fluorescence could not be detected.
Ring-fused pyrazines might be of interest as marker molecules in biochemistry and medicine, are able to
form donor-acceptor complexes which show semi-conducting properties or may serve as light harvesting
systems. In addition, they have found applications as building blocks for phthalocyanine-like macrocycles
9 and for nonlinear optical materials. 10
In this paper, different pyrazino-fused 1,4,5,8-tetraazafulvalenes (3-5,7) were synthesized by
condensation reaction of 2,3,6,7-tetrakis(arylamino) derivatives of type 1 with 2,3-dichloro-5,6-
dicyanopyrazine (2). The best yields were obtained by simple heating (200o C) of a mixture containing 1
and 2 without any solvent or base. As examplified by derivative (3c) the triisopropylsilyl (TIPS)-moiety
is an efficient protecting group for terminal acetylenes under the conditions employed. In addition, the
low solubility of tetraazafulvalenes can be enhanced by introducing such bulky silyl groups at the
peripheral positions. The new derivatives of type (3) were obtained as blue solids upon purification by
column chromatographie. In the well structured UV/VIS spectra of 3a-c the longest wavelength
absorptions are located between 580-590 nm (log ε: 4.9-5.2). In addition, they show especially in
nonpolar solution a strong red fluorescence (3c: λEm = 604 nm, φF = 0.73 in toluene) with a small stokes-
shift of 18 nm (Figure 1). The X-Ray analysis of the deeply blue crystals of 3c succeeded and the result is
shown in Figure 2. The crystal structure clearly verifies the successful ring-fusion reaction and in
addition, a nearly ideal planarization of the tricyclic heterofulvalene.

Ar
HN
Ar
NH
Cl
Cl
N
CN
CN
N
N
N
N
+
HN
Ar
NH
Ar
N
2
1a: Ar = 3-CF3C6H4
1b: Ar = 4-tert-C4H9C6H4
4-(iso-C H ) SiC CC6H4
1c: Ar =
3
9 3
Ar
HN
Ar
N
Ar
N
Ar
N
N
N
CN
CN
NC
NC
N
N
N
N
CN
CN
N
N
N
N
N
N
+
N
N
HN
Ar
N
N
N
4a
Ar
Ar
Ar
3a-c
Ar = 3-CF3C6H4
Ar
N
Ar
N
CH(OC2H5)3
(for 5a and 5b)
N
N
CN
CN
N
N
N
X
X
4a
thiocarbonyl
diimidazole
(for 5c and 5d)
N
N
N
Ar
Ar
5a-d
OC2H5
H
X
X
5b:
5d:
5a: X = C2H5
=
C
X
X
X
5c:
=
C O
=
C
S
X
Scheme 1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
300
400
500
600
700
800
Wavelength [nm]
Figure 1: Normalised absorption and fluorescence spectra of 3c in toluene

Figure 2: Molecular structure and atomic numbering for derivative (3c). Selected distances [Å] and
angles [°]: C1-C1A 1.375(4), C7-C2 1.452(3), N1-C1 1.401(2), N1-C2 1.304(2), N2-C2 1.368(2), N2-C3
1.382(2), N3-C3 1.312(2), N3-C4 1.350 (3), C1A-C1-N1 122.3(2), C1-N1-C2 101.99(15).
The semi-cyclized products (4) could be isolated as byproducts in which both secondary amines allow a
further functionalization. Thus, starting from 4a the reaction with orthoformate is leading to alkylated 5a
as well as cyclized 5b products. Furthermore, 4a can be transformed with thiocarbonyl diimidazole
resulting in new unsymmetric heterofulvalenes (5c) and (5d). Exceptionally 5b, all unsymmetric
derivatives did not show any fluorescence in different solvents.
Ar
N
Ar
N
1b
200o C
N
N
Cl
Cl
N
N
N
N
N
N
N
N
N
N
6
7
Ar
Ar
Scheme 2

Encouraged by the stability and the absorption/emission properties of derivatives (3), other heterocycles
which possess vicinal chlorine atoms were involved. In an analogous fashion, starting from 1a the new
ring-fused derivative (7) is now available with 2,3-dichloroquinoxaline (6) as cyclization partner. In the
UV-VIS spectrum of the tetracyclic heterofulvalene (7) an increasing of absorption intensity was
observed but in contrast to derivatives (3) no fluorescence could be detected.
HC CSi(CH3)3
PdCl2(PPh3)2
CuI, TEA
N N
O
N N
O
R
Ph
Br
Ph
8: R = (CH3)3Si
9: R = H
(C4H9)4N F
Ar1
Ar2
N
N
N
N
N
N
CH(OC2H5)3
C2H5O
OC2H5
N
Ar 2
N
Ar1
10
12
+ 9, PdCl2(PPh3)2, CuI
DMSO, TEA
Ar1
HN
Ar2
NH
N
N
N
N
10, 11: Ar1 = 4-tert-C4H9C6H4; Ar2 = 4-IC6H4
12, 13: Ar1 = 4-tert-C4H9C6H4
HN
Ar2
NH
Ar1
(E/Z)
N
N
Ar2 =
1d: Ar1 = 4-tert-C4H9C6H4
O
Ar2 = 4-IC6H4
Ar1
N
Ar2
N
H5C2O
OC2H5
N
N
N
N
N
N
Ar2
Ar1
11
13
+ 9, PdCl2(PPh3)2, CuI
DMSO, TEA
Scheme 3

Based on these results a further goal was the construction of bichromophores which contain a
tetraazafulvalene core. Therefore, the tetraazafulvalene (1d) (mixture of E/Z-isomers) which possess two
different aryl residues has been prepared. Cyclization with orthoformate gave the imidazo-fused
derivative (10), which was isolated as an unseparable mixture of E/Z and syn/anti-isomers. Analogously,
simple heating of 1d with fluorenone dimethylacetal gaves the bis-spiro compound (11) showing an
orange-red fluorescence. Finally, the imidazo derivatives (10) and (11) have been then cross-coupled
under the conditions of the sonogashira reaction leading to derivatives (12) and (13). Both compounds
represent orange-red solids which show a strong greenish fluorescence.
EXPERIMENTAL
2
2
8
Materials and methods: The tetraazafulvalenes (1a), (1b) and (1c) have been prepared according to
the methods described in the literature. 2,3-Dichloro-5,6-dicyanopyrazine (2) was synthesized according
11
to literature. Other reagents were commercially available and were used without further purification.
All solvents were of reagent grade and were dried and destilled before use.
All reactions were monitored by TLC, carried out on 0.25 mm Merck silicia gel plates (60F254) using UV
1
13
light. H and C NMR spectra were recorded with a Bruker DRX 400 or Bruker AC 250 spectrometer.
Melting points are measured with a galen TM 3 apparatus and are uncorrected. UV-VIS spectra were
recorded on a Perkin-Elmer Lambda 19 spectrophotometer. Fluorescence spectra were measured with an
LS50B luminescence spectrometer (Perkin-Elmer). Fluorescence quantum yields were calculated relative
to quinine sulfate in 0.1N H2SO4 used as a standard (φf = 0.55). MS spectra were taken from
measurements on a Finnigan MAT SAQ 710 mass spectrometer. Elemental analyses were carried out in-
house with an automatic analyzer LECO CHNS 932.
Crystal Structure Determination:

Data collection: The intensity data for the compound (3c) were collected on a Nonius KappaCCD
diffractometer, using graphite-monochromated Mo-Kα radiation. Data were corrected for Lorentz and
polarization effects, but not for absorption. 12,13
Structure Solution and Refinement: The structures were solved by direct methods (SHELXS) 14 and refined
15
by full-matrix least squares techniques against Fo2 (SHELXL-97). The hydrogen atoms were included at
calculated positions with fixed thermal parameters. The molecule of 3c which crystallizes with the solvent
methylene chloride is disordered. The disorder could be solved for the structures. All non-hydrogen atoms
15
were refined anisotropically. XP (SIEMENS Analytical X-ray Instruments, Inc.) was used for structure
representations.
Crystal Data for 3c 16: C86H100N16Si4 * 2 C3H7NO * 2 CH2Cl2, Mr = 1786.22 gmol-1, red-brown prism, size
0.08 x 0.06 x 0.01 mm3, triclinic, space group P-1, a = 8.2071(2), b = 13.9726(3), c = 21.8503(5) Å, α =
89.202(1), β = 83.003(1), γ = 88.404(1)°, V = 2485.9(1) Å3, T= -90 °C, Z = 1, ρcalcd. = 1.193 gcm-3, µ (Mo-
Kα) = 2.22 cm-1, F(000) = 948, 17222 reflections in h(-10/9), k(-18/14), l(-28/26), measured in the range
1.73° ≤ Θ ≤ 27.48°, completeness Θ
= 97.7 %, 11149 independent reflections, Rint = 0.022, 8502
max
reflections with Fo > 4σ(Fo), 559 parameters, 0 restraints, R1obs = 0.062, wR2 = 0.151, R1all = 0.085,
obs
wR2all = 0.170, GOOF = 1.015, largest difference peak and hole: 0.702 / -0.451 e Å-3.
4 5'
5 4'
N ,N -Bis-(4-tert-butylphenyl)-N ,N -bis-(4-iodophenyl)[2,2']biimidazolylidene-4,5,4',5'-tetraamine
(1d): Formamidinium acetate (9.78 g, 0.093 mol) and triethylamine (38.8 mL, 0.29 mol) were added to a
solution of N-(4-iodophenyl)-N-(4-tert-butylphenyl)oxalodiimidoyl dichloride (49.3 g, 0.093 mol) in 200
mL acetonitrile and the resulting solution was heated under reflux for 3 h. After cooling to rt, the solvent
was evaporated under reduced pressure to dryness. Methanol was added under vigorous stirring, the
resulting solid was removed by filtration and then air-dried to provide brown-reddish crystals of
compound (1d). Yield 24 g (26 %), mp 235-240°C (DMF), mixture of E/Z isomers. - 1H NMR (250 MHz,
DMSO-d6): δ = 1.24 (s, 18H), 1.34 (s, 18H), 7.38-7.78 (m, 32H). MS (CI) m/z (%): 125(100), 157(97),

861(42)[M+]. Anal. Calcd for C38H38N8I2 : C, 53.04; H, 4.45; N, 13.02. Found: C, 53.14; H, 4.52; N,
12.94.
General procedure for the synthesis of Tetraazafulvalenes (3a-c) and the semicyclized product (4a):
Tetraazafulvalenes (1a-c) (0.13 mmol) and 2,3-dichloro-5,6-dicyanopyrazine (2) (300 mg, 1.51 mmol)
were heated at 200o C under argon for 15 min. After cooling to rt the crude product was purified by
column chromatography (Al2O3, toluene/acetone). Recrystallization from DMF gave derivatives (3a-c)
and (4a).
4,9,4',9'-Tetrakis-(3-trifluoromethyl-phenyl)-4,9,4',9'-tetrahydro[2,2']bi[1,3,4,5,8,9-hexaaza-
cyclopenta[b]naphthalenylidene]-6,7,6',7'-tetracarbonitrile (3a): Yield 68 mg (49 %), mp > 250°C
1
(DMF). - H NMR (400 MHz, DMSO-d6): δ = 7.84 (m, 8H), 7.89 (m, 4H), 7.94 (d, J = 8.0 Hz, 4H). -
UV-VIS (DMSO): λmax/nm (log[ε/dm3 mol-1 cm-1]) 498 (4.2), 529 (4.6), 570 (4.8). Fmax: 591 nm, φF =
0.69. - IR : νmax/cm-1 2213 (CN). MS (DCI, water) m/z (%): 162 (20), 306 (18), 1021 (M+1)+. Anal. Calcd.
for C46H16N16F12: C, 54.13; H, 1.58; N, 21.96. Found C, 54.25; H, 1.62; N, 21.86.
4,9,4',9'-Tetrakis-(4-tert-butylphenyl)-4,9,4',9'-tetrahydro[2,2']bi[1,3,4,5,8,9-hexaaza-
cyclopenta[b]naphthalenylidene]-6,7,6',7'-tetracarbonitrile (3b): Yield 65 mg (48%), mp >250°C (DMF).
1
- H NMR (THF-d8) : δ = 1.32 (s, 36 H), 7.36 (d, J = 8.0 Hz, 8H), 7.52 (d, J = 8.0 Hz, 8H). - UV-
VIS (toluene): 509 (4.5), 545 (4.9), 588 (5.1). Fmax: 606 nm, φF = 0.72. IR : 2233 (CN). - MS (DCI, water)
m/z (%): 972 (100) (M)+. Anal. Calcd for C58H52N16: C, 71.59; H, 5.39; N, 23.03. Found: C, 71.68; H,
5.46; N, 22.95.
4,9,4',9'-Tetrakis-{4-[(triisopropylsilanyl)ethynyl]phenyl}-4,9,4',9'-tetrahydro[2,2']bi[1,3,4,5,8,9-
hexaazacyclopenta[b]naphthalenylidene]-6,7,6',7'-tetracarbonitrile (3c): Yield 60 mg (50 %), mp
>250°C (DMF). - 1H NMR (CD2Cl2): δ = 1.09 (s, 72 H), 1.19 (s, 12 H), 7.29(d, J = 8.5 Hz), 7.62 (d, J =
8.5 Hz, 8 H). - UV-VIS (toluene): 508 nm (4.5), 543 (4.9), 586 (5.2). Fmax: 604 nm, φF = 0.73. - IR (film):
ν
max/cm-1 2155 (C≡C), 2235 (CN). - MS (ESI) m/z (%): 1215.9 (30), 1469.8 (100)(M+1)+, 1491.8
(M+Na)+. Anal. Calcd for C86H100N16Si4: C, 70.26; H, 6.86; N, 15.24. Found: C, 70.06; H, 6.95; N, 15.43.
2-[4,5-Bis-(3-trifluoromethylphenylamino)imidazol-2-ylidene]-4,9-bis-(3-trifluoromethylphenyl)-4,9-

dihydro-2H-1,3,4,5,8,9-hexaazacyclopenta[b]naphthalene-6,7-dicarbonitrile (4a): Yield 10 mg (10 %),
mp> 250°C (DMF). - 1H-NMR (250 MHz, CD2Cl2) : δ = 7.35 (m, 4H), 7.48 (d, J = 8.7 Hz, 1H), 7.63 (m,
4 H), 7.80 (m, 4H), 7.89 (d, J = 8.0 Hz, 1H), 7.98 (s, 1H), 8.15 (d, J = 8.4 Hz, 1H). - UV-VIS (DMSO):
λ
max/nm (log[ε/dm3 mol-1 cm-1]) 533 (4.7), 558 (4.8). – IR (film) : νmax/cm-1 2236 (CN). - MS (DCI,
water) m/z (%): 149 (100), 537 (20), 894 (40)(M+). Anal. Calcd for C50H18N16F12 : C, 53.70; H, 2.03; N,
18.79. Found: C, 53.86; H, 2.09; N, 18.72.
Syntheses of Unsymmetric Tetraazafulvalenes (5a – 5d): Compound (4a) (100 mg, 0.11 mmol) was
heated in triethylorthoformate (5 mL) under reflux under a stream of argon for 12 h. The orthoformate
was evaporated and the residue was purified by column chromatography with Al2O3 and toluene to give
at first compound (5a) and then (5b).
Compound (5a): Yield 30 mg (29 %), mp 206 °C (acetone). - 1H NMR (250 MHz, CD2Cl2): δ = 1.05 (t, J
= 6.86 Hz, 6 H), 4.27 (q, J = 6.81 Hz, 4 H), 6.58 (dd, J = 6.72 and 7.81 Hz, 2 H), 6.68 (s, 2H), 7.03 (m,
4H), 7.75 (m, 4 H), 7.79 (dd, J = 7.80 and 8.03 Hz, 2 H), 7.86 ( s, 2H). - UV-VIS (toluene): λmax/nm
(log[ε/dm3 mol-1 cm-1]) 566 (4.7). IR : νmax/cm-1 2230 (CN). - MS (DCI, water) m/z (%): 416 (90), 931
(20), 951 (60)(M+1)+. Anal. Calcd for C44H26N12F12: C, 55.59; H, 2.76; N, 17.68. Found: C, 55.80; H,
2.81; N, 17.57.
1
Compound (5b): Yield 50 mg (48 %), green crystals, mp 160°C (decomp). - H NMR (250 MHz,
CD2Cl2): δ = 1.01 (t, J = 7.01 Hz, 3 H), 3.40 (q, J = 6.45 Hz, 2 H), 7.52 (d, J = 7.68, 2 H), 7.61 (dd, J =
7.84 and 8.07 Hz, 2H), 7.71 (m, 4 H), 7.90 (d, J = 7.68 Hz, 2H), 8.05 (s, 1H), 8.13 (m, 4 H), 8.24 (dd, J =
7.72 and 8.12 Hz, 2H). - UV/VIS (DMSO): 451 nm (4.5), 477 (4.7), 510 (4.8). - UV-VIS (toluene):
λ
max/nm (log[ε/dm3 mol-1 cm-1]) 502 (4.8). Fmax: 569 nm. MS (DCI, water) m/z (%): 526 (100), 931 (25),
951(50)(M+1)+. Anal. Calcd for C43H22N12OF12: C, 54.33; H, 2.33; N, 17.68. Found: C, 54.44; H, 2.39;
N, 17.60. Tetraazafulvalene (4a) (100 mg, 0.11 mmol) was heated with thiocarbonyldiimidazole (44 mg,
0.25 mmol) at 200°C for 15 min. The resulting mixture was purified by column chromatography (Al2O3,

toluene) to give derivatives (5c) and (5d). Compound (5c): Yield: 42 mg (43 %), green crystals, mp
>250°C (decomp). - UV-VIS (THF): λmax/nm (log[ε/dm3 mol-1 cm-1]) = 528 (4.6), 550 (4.6). IR: νmax/cm-1
2238 (CN), 1729 (C=S). - MS (DCI, water) m/z (%): 391 (90), 847 (40), 889 (20)(M+1)+. Anal. Calcd for
C53H52N12S: C, 71.60; H, 5.89; N, 18.90. Found: C, 71,89; H, 5.96; N, 18.78.
Compound (5d): Yield 15 mg (15 %). red crystals, mp >250°C (decomp). - UV/VIS (THF): λmax/nm
(log[ε/dm3 mol-1 cm-1]) 512 (4.5). - IR: νmax/cm-1 2237 (CN), 1724 (C=O). - MS (DCI, water) m/z (%):
391 (40), 647 (5), 873 (20)(M+1)+. Anal. Calcd for C53H52N12O: C, 72.91; H, 6.00; N, 19.25. Found: C,
73.02; H, 6.09; N, 19.16.
Synthesis of tetraazafulvalene (7): Tetraazafulvalene (1b) (100 mg, 0.13 mmol) and 2,3-
dichloroquinoxaline (200 mg) were heated under argon for 8 h. After cooling to rt the crude product was
purified by recrystallisation from DMF to give the tetracyclic derivative (7).
Compound (7): Yield 42 mg, (33 %), green crystals, mp > 300 °C (DMF) - 1H NMR (400 MHz, THF-d8):
δ = 1.29 (s, 36 H), 7.29 (d, J = 8.0 Hz, 8H), 7.34 (m, 16 H), 7.69 (m, 8 H). - UV-VIS (THF): λmax/nm
(log[ε/dm3 mol-1 cm-1]) 545 (5.1). - MS (DCI, water) m/z (%): 205 (100), 485 (40), 973 (60)(M+1)+. Anal.
Calcd for C62H60N12: C, 76.52; H, 6.21; N, 17.27. Found C, 76.47; H, 6.25; N, 17.23.
Synthesis of the acetylene (9): To a solution of 2-(4-bromophenyl)-5-phenyl-1,3,4-oxadiazole (0.5 g, 1.6
mmol) in triethylamine (5 mL), PdCl2(PPh3)2 (0.07 g, 0.1 mmol ) and CuI (0.038 g, 0.2 mmol ) were
added and the mixture was then stirred under an argon atmosphere. After 10 min, trimethylsilylacetylene
(0.7 mL, 6.4 mmol) was added by the syringe. The resulting mixture was heated at 100 °C under argon
for 3 h. After cooling to rt, the solution was filtred off, washed with triethylamine (1x20 mL) and
methylene chloride (1x10 mL). The solvents were evaporated under reduced pressure to give the crude
product, which was subjected to column chromatography (Al2O3, toluene) to obtain the acetylene (8).

2-(4-(Trimethylsilylethinyl)phenyl)-5-phenyl-1,3,4-oxadiazole (8): Yield 0.5 g (96 %), brown crystals, mp
1
154-156°C (heptane). - H NMR (250 MHz, CDCl3): δ = 0.21 (s, 9H), 7.46-7.56 (m, 5H), 8.00-8.09 (m,
4H). - MS (DEI) m/z (%): 183(40), 262(60), 277(23), 303(100), 318(91)[M+]. Anal. Calcd for
C19H18N2OSi: C, 71.66; H, 5.70; N, 8.80. Found: C, 71.53; H, 5.73; N, 8.85.
Compound (8) was dissolved in THF (15 mL), Bu4NF (1 M in THF, 0.4 mL) was added until TLC
analysis showed complete conversion. The solution was evaporated to dryness under reduced pressure
and the crude product was chromathographed with petrol ether/acetone (4:1) to give the acetylene (9).
2-(4-Ethinylphenyl)-5-phenyl-1,3,4-oxadiazole (9): Yield 0.32 g (83 %), beige crystals, mp 114-117°C
(toluene). - 1H NMR (250 MHz, CDCl3): δ = 3.28 (s, 1H), 7.56 - 7.61 (m, 5H), 8.12-8.19 (m, 4H). - UV-
VIS (CH2Cl2) : λmax/nm (log[ε/dm3 mol-1 cm-1]): 298 (4.9). Fmax: 384, 364 nm. - MS (EI) m/z (%) = 189
(71), 246 (100)[M+]. Anal. Calcd for C16 H10N2O: C, 78.04; H, 4.09; N, 11.38. Found: C, 78. 14; H, 4.03;
N, 11.30.
Synthesis of cyclic aminals (10) and (11):
Compound (10) was prepared by condensation of 1d (2.00 g, 2.32 mmol) with triethyl orthoformate (20
mL, 0.12 mol) by heating under reflux in an argon stream for 7 h. The cooled solution was evaporated to
dryness under reduced pressure. Purification by column chromatography (Al2O3, petrol ether/toluene, 2:1)
afforded 10 as green crystals 0.79 g (35%). mp 150-155°C (DMF), mixture of 4 isomers. - 1H NMR (250
MHz, DMSO - d6): δ = 0.95 (t, J = 7.0 Hz, 24 H), 1.24 (s, 72 H), 3.31 (q, J = 7.0 Hz, 16 H), 7.58-7.97 (m,
72 H). - UV-VIS (toluene) : λmax/nm (log[ε/dm3 mol-1 cm-1]) 464 (4.9), 497 (5.0). Fmax: 504, 543 nm, φF =
0.78 (toluene). - MS (CI) m/z (%) = 973(100)[M+]. Anal. Calcd for C44 H46N8O2I2: C, 54.33; H, 4.77; N,
11.52. Found: C, 54.48; H, 4.84; N, 11.42.

Compound (11) was prepared by heating of 1d (0.32 g, 0.37 mmol) with fluoren-9-one diethyl acetal
(2.15 g, 8.46 mmol) in xylene (10 mL) under reflux in an argon stream for 7 h. The cooled solution was
evaporated to dryness under reduced pressure and further purified by column chromatography (Al2O3,
toluene and then toluene/acetone, 2:1). Spiro aminal (11) was obtained as brown crystals, 0.24 g (54 %).
1
mp 100-105°C (acetone), mixture of E/Z isomers. - H NMR (DMSO-d6): δ = 1.26 (s, 36 H), 7.29-7.75
(m, 64H). - UV-VIS (toluene) : λmax/nm (log[ε/dm3 mol-1 cm-1]) 476 (4.6), 506 (4.7). - MS (DCI, water)
m/z (%): 218(42), 845(95), 1023(100), 1185(40)[M+]. Anal. Calcd for C64 H50N8I2: C, 64.87; H, 4.25; N,
9.46. Found: C, 64.99; H, 4.30; N, 9.34.
Synthesis of cross-coupling products (12) and (13): In a Schlenk tube a mixture of DMSO (9 mL) and
TEA (9 mL) were added to PdCl2(PPh)3 (29 mg, 0.04 mmol) and CuI (0.018 g, 0.08 mmol. Upon addition
of derivative (10) (in the case of 12) (0.19 g, 0.20 mmol) or 11 (in the case of 13) (0.24 g, 0.20 mmol) the
mixture was stirred under argon atmosphere for 15 min. Acetylene (9) (0.101 g, 0.4 mmol) was then
added and the resulting reaction mixture was stirred under argon, maintaining the temperature between
35-40°C for about 3 h until the reaction was completed by TLC. After cooling to rt, the triethylamine was
removed under vacuo, and water was added affording a dark brown precipitate. The crude product was
filtred off, washed with water (3x20 mL), and thoroughly dried. Purification was realized by
chromatography on a short column (Al2O3, toluene, toluene/acetone). Recrystallization from acetone
afforded the pure product (12) or (13).
1
Compound (12): Yield 70 mg (30 %), red powder, mp 228-230°C (DMF), mixture of 4 isomers. - H
NMR (250 MHz, CD2Cl2): δ = 1.01 (m, 24 H), 1.31 (s, 36 H), 1.46 (s, 36 H), 3.32 (m, 16 H), 7.42-8.10
(m, 144 H). - UV-VIS (toluene): λmax/nm (log[ε/dm3 mol-1 cm-1]) 320 (4.8), 446 (4.7), 476 (4.9), 512
(5.1). Fmax (toluene): 518 nm, 560. - IR: νmax/cm-1 2208 (C≡C). - MS (ESI, toluene/methanol) m/z (%):
635(100), 1184.5(30), 1209.5(40)[M+]. Anal. Calcd for C76H64N12O4: C, 75.48; H, 5.33; N, 13.90. Found:

C, 75.61; H, 5.43; N, 13.78.
1
Compound (13): Yield 76 mg (26 %), red powder, mp 190-192°C (DMF), mixture of E/Z-isomers. - H
NMR (250 MHz, CDCl3): δ =1.18 (s, 18H), 1.26 (s, 18 H), 6.98-8.05 (m, 100 H). - UV-VIS (DMSO):
λ
max/nm (log[ε/dm3 mol-1 cm-1]) 330 (4.8), 489 (4.6), 515 (4.8). - IR: νmax/cm-1 2210 (C≡C). - MS (ESI)
m/z (%): 1420.5 (M+)(100). Anal. Calcd for C96 H68N12O2: C, 81.11; N, 4.82; N, 11.82. Found: C, 81.25;
H, 4.90; N, 11.72.
ACKNOWLEDGEMENTS
This work was supported by Roche Diagnostics GmbH, Penzberg, Deutsche Forschungsgemeinschaft
(DFG, SFB 436) and the Fonds der Chemischen Industrie.
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Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK;
fax: (+44) 1223-336-033; or deposit@ccdc.cam.ac.uk).