Highly efficient synthesis of linear pyrrole oligomers by twofold Heck reactions

Article abstract of DOI:10.1002/1521-3765(20010119)7:2<368::AID-CHEM368>3.0.CO;2-2

The twofold Heck reaction of the vinylpyrroles 3a and 3b with the iodobenzenes 4a-c led to the linear pyrrole oligomers 5, 6, and 7. The synthesis of both symmetrical and unsymmetrical oligomers, such as 10a and 10b, was also accomplished by a Heck reaction of 8 and 9 and by a Heck reaction of 3a and 11 followed by a Wittig reaction and a second Heck reaction with 8. The pentacyclic oligomers 14 and 19 were prepared by a twofold Heck reaction of 13 with 4 and by a twofold Heck reaction of 15 with 16 followed by a Wittig reaction and a twofold Heck reaction with 8.

Full text of DOI:10.1002/1521-3765(20010119)7:2<368::AID-CHEM368>3.0.CO;2-2

FULL PAPER
Highly Efficient Synthesis of Linear Pyrrole Oligomers
by Twofold Heck Reactions
Lutz F. Tietze,* Georg Kettschau, Ulrich Heuschert, and Gero Nordmann[a]
Abstract: The twofold Heck reaction of the vinylpyrroles 3a and 3b with the
iodobenzenes 4a ± c led to the linear pyrrole oligomers 5, 6, and 7. The synthesis of
both symmetrical and unsymmetrical oligomers, such as 10a and 10b, was also
accomplished by a Heck reaction of 8 and 9 and by a Heck reaction of 3a and 11
followed by a Wittig reaction and a second Heck reaction with 8. The pentacyclic
oligomers 14 and 19 were prepared by a twofold Heck reaction of 13 with 4 and by a
twofold Heck reaction of 15 with 16 followed by a Wittig reaction and a twofold
Heck reaction with 8.
Keywords: Heck reactions ´ palla-
dium ´ polypyrroles ´ pyrroles ´
Wittig reactions
properties.[4] Today this class of compounds represents a
research field of its own. While there has been substantial
progress in the synthesis of other types of p-conjugated
oligomers,[5] straightforward synthesis of higher linear oligom-
ers of pyrrole remains challenging.[6] Recently we reported on
novel linear oligopyrroles.[7] Herein we describe the efficient
synthesis of oligopyrroles 5, 6, 7, 10, 14, and 19 being
connected by divinylbenzene units using twofold Heck
reactions.[8]
Introduction
Linear oligomeric pyrroles are key building blocks in biosyn-
thesis[1] and are also of interest for the synthesis of novel
macrocycles.[2] This may be exemplified by the linear tetra-
meric pyrromethane hydroxymethylbilane 1 being the pre-
cursor of the porphyrins such as heme 2 (Scheme 1), the
chlorophylls and vitamin B12.[1]
Results and Discussion
N
N
N
A
P
A
P
A
P
A
P
For the synthesis of the linear 2-divinylbenzene-1,3-bis-
pyrroles 5, 6 and 7, N-Boc-vinylpyrroles 3a and 3b[7] were
treated with meta-[9], para-, and ortho-diiodobenzene in the
presence of catalytic amounts of palladium (see Scheme 2). A
major problem in the transformations of 3b was the control of
regioselectivity at the vinyl group. Thus, reaction of 3b under
the usual reaction conditions gave a mixture of constitutional
isomers. However, by employing silver acetate as base only
the linear products were obtained. Silver phosphate and silver
carbonate proved to be less effective for this purpose.
Reaction of 3b with m-diiodobenzene 4a provided 5b with
33% yield, reaction of 3b with p-diiodobenzene 4b gave 6b
with 28% yield and that of 3b with o-diiodobenzene 4c led to
7b in only 10% yield. The lower yield of the reaction of 4c
with o-substitution is in accord with the increased steric
hindrance at the reaction centers compared with 4a and 4b. In
the transformations of 3a the linear oligomers were obtained
in the absence of a silver salt. Moreover, for these reactions it
was in some cases appropriate to use triethylamine as solvent
to obtain good results. Reaction of 3a with 4a gave 5a in 48%
Fe
N
N
N
N
N
H
H
H
H
OH
1: A= CH2CO2H; P = CH2CH2CO2H
HO2C
CO2H
2
Scheme 1. Hydroxymethylbilane 1 and heme 2.
Further, polypyrroles in their oxidized form are of interest as
organic conductors and LED materials.[3] In recent years p-
conjugated oligomers of defined structure gained more and
more interest due to their inherent electronic and optical
[a] Prof. Dr. Dr. h.c. L. F. Tietze, Dr. G. Kettschau,
Dipl. Chem. U. Heuschert, Dipl. Chem. G. Nordmann
Institut für Organische Chemie
Georg-August-Universität Göttingen
Tammannstraûe 2, 37077 Göttingen (Germany)
Fax : (‡ 49)551-399476
E-mail: ltietze@gwdg.de
368
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Chem. Eur. J. 2001, 7, No. 2

368±373
2
+
EtO2C
I
N
Boc
8
9
Pd0, 35%
R1
R1
R1 R2
10
R2
Boc
N
N
H
H
a
b
Boc
CH3 CO2Et
CO2Et
10
Pd0,
8, 59%
I
Pd0, 47%
+
N
N
CHO
Boc
Boc
R
Scheme 2. Synthesis of the tricyclic compounds 5 ± 7.
3a
11
12: R = CHO
13: R = CH=CH2, 72%
Ph3P=CH2
yield, that of 3a with 4b oligomer 6a in 37% yield and that of
3a with 4c compound 7a in 47% yield. The decreased
regioselectivity under normal conditions and the lower yield
in the reaction of 3b is probably due to a strong 1,3-allylic
strain[10] in the transition state leading to 5 ± 7 due to the
methyl group at C-3 of the pyrrole moiety of 3b. Such a 1,3-
allylic strain has recently been shown by us to be of
importance in the cyclisation of hydroxymethylbilane.[1f] The
improvement of the regioselectivity in the reaction of 3b by
addition of silver salt can be explained by the intermediate
Scheme 3. Synthesis of the tricyclic compounds 10a and 10b.
I
I
N
2
+
Boc
13
4
Pd0, 77%
‡
formation of a Pd species which would generally increase the
reactivity and also lower the steric interaction of the Pd
attacked to a-position of the vinyl group in 3b. However,
electronic effects may also have some influence. Thus,
Hallberg and others[11] showed that electron rich palladium
species favor an a-arylation.
N
N
Boc
Boc
For the formation of oligomers of type 5 ± 7 a second
approach is also feasible, namely the use of a divinylbenzene
and an iodopyrrole. This is exemplified by the preparation of
the p-substituted system 10b (see Scheme 3) from 8[12] and
9.[13] Reaction of 8 and 9 in the presence of catalytic amounts
of palladium led to 10b in 35% yield. Here and in some other
reactions, especially when using iodopyrroles, the presence of
triphenylphosphane is not suitable since decomposition may
occur. This effect has been recognized by us for several
different transformations. For the preparation of unsymmet-
rical oligomers we have also developed a stepwise approach in
which first a Pd-catalyzed reaction of a vinylpyrrole 3a with p-
iodobenzaldehyde (11)[14] leads to the pyrrole derivative 12.
Wittig reaction gives the corresponding vinylbenzenepyrrole
13, which now can react in a second Heck reaction with the
iodopyrrole 8 to give 10 in 20% yield over three steps.
The vinyl derivative 13 could also be subjected to a twofold
Heck reaction with m-diiodobenzene (4). This transformation
gave the pentacyclic oligomer 14 in 77% yield which contains
two pyrrole and three divinylbenzene moieties (Scheme 4).
Of particular interest for the synthesis of higher linear
oligomeric pyrroles is the 2,5-diiodopyrrole derivative 15,
which is easily accessible from the corresponding dibromo
14
Scheme 4. Synthesis of 14.
derivative by halogen metal exchange with nBuLi and
quenching with iodine.[15] The 2,5-dibromopyrrole can be
obtained from pyrrole itself through bromination followed by
protection with di-tert-butyldicarbonate according to the
protocol of Cava[15] in 83% yield. While the 2,5-dibromopyr-
role derivative is usually not sufficiently reactive in Heck
ꢀ
reactions, 15 undergoes Pd-catalyzed C C bond formation
with several acceptor substituted alkenes, for example acrylic
acid esters or p-vinylbenzaldehyde (16) (Scheme 5).[16] Two-
fold Heck reaction of 15 with 16 led to the pyrrole derivative
17, which gave the bisvinyl derivative 18 using a twofold Wittig
reaction. Compound 18 reacts with the iodopyrrole 8 again in
a twofold Heck reaction to give the red pentacyclic oligomer
19 in 28% yield.
The structures of the newly formed oligopyrroles were
determined mainly by NMR spectroscopy. The spectra are
rather simple due to the symmetry of the molecules. As an
1
example the H NMR spectrum of 19 is discussed in detail.
The hydrogens at the four double bonds resonate as a doublet
Chem. Eur. J. 2001, 7, No. 2
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369

L. F. Tietze et al.
FULL PAPER
TLC chromatography was performed on aluminum precoated silica gel SIL
G/UV254 plates (Macherey ± Nagel GmbH), and silica gel 32 ± 63 (0.032 ±
0.064 mm) (Macherey ± Nagel GmbH) was used for column chromatogra-
phy(eluent 1: light petroleum/EtOAc 15:1; eluent 2: 10:1; eluent 3: 4:1;
eluent 4: 15:1 ‡ 1% NEt3; eluent 5: 10:1 ‡ 1% NEt3; eluent 6: 4:1 ‡ 1%
NEt3). UV/Vis spectra (lmax [nm], log e) were recorded in CH3CN on a
Mettler Lambda2 spectrometer. IR spectra were recorded as KBr pellets
or as films on a Bruker IFS 25 or Vector 22 spectrometer. 1H and 13C NMR
spectra were recorded on a Varian XL200, VXR200, and VXR500 or a
Bruker AM300 with tetramethylsilane (TMS) as internal standard in
CDCl3 or [D6]benzene. Multiplicities of 13C NMR peaks were determined
with the APT pulse sequence. Mass spectra were measured at 70 eV on a
Varian MAT 311A, high-resolution mass spectra on a Varian MAT 731
instrument. Melting points are measured on a Mettler FP 61.
CHO
+
I
2
I
N
Boc
15
16
Pd0, 67%
N
O
O
Boc
17
Ph3P=CH2, 62%
General procedure I. Wittig reaction: nBuLi (1.1 mol equiv, 2.1m solution
in n-hexane) was added dropwise at 08C to a stirred suspension of methyl
triphenylphosphonium iodide (1.2 mol equiv) in THF (10 mL per mmol
aldehyde). Stirring was continued for 2 h at 08C and the aldehyde
(1.0 equiv) in THF was added dropwise to the solution at ꢀ788C. After
stirring for 15 min at this temperature the solution was warmed to room
temperature and stirred for additional 30 min. The reaction was quenched
by adding water, then the organic layer was separated and the aqueous
layer extracted with Et2O (3 Â ). The combined organic layers were washed
with water and brine, dried over Na2SO4, and evaporated in vacuo. The
obtained crude product was purified by column chromatography.
N
Boc
18
Pd0, 2 EtO2C
, 28%
I
N
Boc
8
General procedure II. Heck reaction with pyrroles
Variant a: A stirred suspension of potassium acetate (4.0 mol equiv) and
tetrapropylammonium bromide (1.0 mol equiv) in DMF (20 mL per mmol
substrate) was degassed by freeze and pump methodology. Palladium
acetate (5 mol%), triphenylphosphane (10 mol%) and the substrates were
added. The vigorously stirred reaction mixture was slowly heated to the
indicated temperature. After complete transformation (TLC) the reaction
mixture was cooled to room temperature and water (20 mL per mmol
substrate) and Et2O (40 mL per mmol substrate) were added. The aqueous
layer was extracted with Et2O (3 Â ). The combined organic phases were
washed with water and brine, dried over Na2SO4, and evaporated in vacuo.
The obtained crude products were purified by column chromatography.
2'
2'
Boc
2'''
N
Boc
N
N
Boc
2'''
1'
1'
EtO2C
CO2Et
1'''
1'''
19
Scheme 5. Synthesis of 19.
at d ˆ 6.79 with J ˆ 16.5 Hz for the 1'''-H, at d ˆ 6.93 with J ˆ
16.0 Hz for the 2'-H, at d ˆ 7.65 with J ˆ 16.5 Hz for the 2'''-H
and at d ˆ 7.86 with J ˆ 16.0 Hz for the 1'-H. The large
coupling constants of J ˆ 16.0 and 16.5 Hz confirm that all
double bonds have an (E)-configuration. The hydrogens at
the central pyrrole unit and the arenes resonate as singlets at
d ˆ 6.55 and d ˆ 7.40, respectively. For the methyl groups at
the pyrrole units singlets at d ˆ 1.93 and 2.20 are observed.
The UV/Vis spectrum documents the extended p-conjugated
system with lmax ˆ 431 nm and log e ˆ 4.858.
Variant b: The reaction was performed in the absence of triphenylphos-
phane.
Variant c: The reaction was performed in the presence of silver acetate
(4.0 mol equiv) instead of potassium acetate and tetrapropylammonium
bromide.
Variant d: The reaction was performed in the presence of triethylamine
instead of potassium acetate and tetrapropylammonium bromide. For this
purpose triethylamine was degassed in a pressure flask by bubbling argon
through for 0.5 h and after addition of palladium acetate (5 mol%),
triphenylphosphane (10 mol%) and the substrates the reaction mixture
was degassed for another 10 min.
(E,E)-1,3-Bis-[2'-(1''-tert-butoxycarbonyl-[1''H]-pyrrol-2''-yl)-vinyl]-ben-
zene (5a): According to general procedure IId the vinylpyrrole 3a (293 mg,
1.50 mmol, 1.3 equiv) was reacted with 1,3-diiodobenzene 4a (165 mg,
500 mmol, 1.0 equiv) for 24h at 908C. Column chromatography (20 g silica
gel, eluent 2) afforded 5a (111 mg, 241 mmol, 48%) as a yellow oil. tR ˆ 0.40
Conclusion
The combination of several Heck reactions as well as of Wittig
and Heck reactions allows a simple and highly efficient access
to linear p-conjugated oligomeric pyrrole derivatives. Here
the synthesis of defined oligomers with up to five arene and
ꢀ
ˆ
(eluent 2); IR (KBr): nÄ ˆ 3004, 2978, 2932 (C H), 1742 (C O), 1624, 1594,
ꢀ1
ˆ
ꢀ
1552 (C C), 958 cm (C H, (E)-alkene); UV (CH3CN): lmax (log e) ˆ
237.5 (4.280), 330.0 nm (4.574); 1H NMR (500 MHz, C6D6): d ˆ 1.29 (s,
18H, C(CH3)3), 6.13 (t, J ˆ 3.5 Hz, 2H, 4''-H), 6.53 (ddd, J ˆ 3.5, 2.0, 1.0 Hz,
2H, 3''-H), 6.93 (d, J ˆ 16.5 Hz, 2H, 1'-H), 7.11 (t, J ˆ 7.5 Hz, 1H, 5-H), 7.33
(dd, J ˆ 7.5, 2.0 Hz, 2H, 4-H, 6-H), 7.37 (dd, J ˆ 3.5, 2.0 Hz, 2H, 5''-H), 7.67
(brs, 1H, 2-H), 8.14 (d, J ˆ 16.5 Hz, 2H, 2'-H); 13C NMR (50.3 MHz,
CDCl3): d ˆ 28.0 (C(CH3)3), 83.8 (C(CH3)3), 110.8 (C-4''), 111.1 (C-3''),
119.8 (C-2'), 122.2 (C-5''), 124.5 (C-2), 125.2 (C-4, C-6), 128.0 (C-1'), 128.8
ˆ
pyrrole units connected by C C-double bonds is described.
However, the approach could also be employed for the
synthesis of higher oligomers.
ˆ
(C-5), 134.3 (C-2''), 137.9 (C-1, C-3), 149.4 (C O); MS (70 eV): m/z (%):
‡
‡
‡
460 (37) [M] , 360 (15) [M ꢀ CO2C4H8] , 348 (28) [M ꢀ 2 Â C4H8] , 304
Experimental Section
‡
‡
(41) [M ꢀ CO2C4H8 ꢀ C4H8] , 260 (100) [M ꢀ 2 Â CO2C4H8] , 57 (13)
‡
[C4H9] ; C28H32N2O4 (460.6): calcd C 73.02, H 7.00; found C 73.06, H 6.97.
All reactions were performed under nitrogen or argon atmosphere in
flame-dried flasks, and the reactants were introduced by syringe. All
solvents were dried by standard methods. Solvents used in Pd-catalyzed
reactions were degassed by pump and freeze methodology. All reagents
obtained from commercial sources were used without further purification.
(E,E)-1,3-Bis-[2'-(1''-tert-butoxycarbonyl-3'',4''-dimethyl-[1''H]-pyrrol-2''-
yl)-vinyl]-benzene (5b): According to general procedure IIc the vinyl-
pyrrole 3b (277 mg, 1.25 mmol, 1.3 equiv) was treated with 1,3-diiodoben-
zene 4a (165 mg, 500 mmol, 1.0 equiv) for 4 h at 908C. Column chromatog-
370
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Chem. Eur. J. 2001, 7, No. 2

Pyrrole Oligomers
368±373
ꢀ
ˆ
raphy (10 g silica gel, eluent 1) afforded 5b (85.0 mg, 165 mmol, 33%) as a
oil. tR ˆ 0.48 (eluent 1); IR (KBr): nÄ ˆ 2980, 2930, 2862 (C H), 1732 (C O),
ꢀ1
ꢀ
ˆ
ꢀ
pale yellow oil. tR ˆ 0.48 (eluent 1); IR (KBr): nÄ ˆ 2978, 2932 (C H), 1734
1600, 1524 (C C), 962 cm (C H, (E)-alkene); UV (CH3CN): lmax (log
e) ˆ 251.0 nm (4.202), 313.0 (4.345), 341.0 (4.284); 1H NMR (200 MHz,
C6D6): d ˆ 1.32 (s, 18H, C(CH3)3), 1.85 (s, 6H, 4''-CH3), 2.07 (s, 6H, 3''-
CH3), 7.09 (dd, J ˆ 6.0, 3.5 Hz, 2H, 4-H, 5-H), 7.20 (s, 2H, 5''-H), 7.27 (d, J ˆ
16.5 Hz, 2H, 1'-H), 7.82 (dd, J ˆ 6.0, 3.5 Hz, 2H, 3-H, 6-H), 7.95 (d, J ˆ
16.5 Hz, 2H, 2'-H); 13C NMR (50.3 MHz, CDCl3): d ˆ 10.36, 11.46 (3''-CH3,
4''-CH3), 28.09 (C(CH3)3), 82.96 (C(CH3)3), 118.3 (C-5''), 122.1 (C-3''), 122.3
(C-2'), 122.5 (C-4''), 125.9, 127.1, 127.2 (C-3, C-4, C-5, C-6, C-1'), 129.7 (C-
ꢀ1
ˆ
ˆ
ꢀ
(C O), 1626, 1594, 1578, 1520 (C C), 960 cm (C H, (E)-alkene); UV
(CH3CN): lmax (log e) ˆ 242.5 (4.314), 327.5 nm (4.527); 1H NMR
(300 MHz, [D6]DMSO): d ˆ 1.53 (s, 18H, C(CH3)3), 1.96 (s, 6H, 4-CH3),
2.10 (s, 6H, 3-CH3), 6.64 (d, J ˆ 16.5 Hz, 2H, 1'-H), 7.07 (s, 2H, 5''-H), 7.31 ±
7.42 (m, 3H, 4-H, 5-H, 6-H), 7.53 (d, J ˆ 16.5 Hz, 2H, 2'-H), 7.61 (brs, 1H,
2-H); 13C NMR (50.3 MHz, CDCl3): d ˆ 10.38, 11.38 (3-CH3, 4-CH3), 28.11
(C(CH3)3), 82.97 (C(CH3)3), 118.4 (C-5''), 120.7 (C-2'), 122.2, 122.7 (C-3'',
‡
ˆ
C-4''), 124.3 (C-2), 124.8 (C-4, C-6), 128.8 (C-5), 129.4 (C-2''), 129.7 (C-1'),
2''), 135.9 (C-1, C-2), 149.4 (C O); MS (70 eV): m/z (%): 516 (41) [M] , 416
‡
‡
‡
ˆ
138.2 (C-1, C-3), 149.5 (C O); MS (70 eV): m/z (%): 516 (23) [M] , 416
(14) [MꢀCO2C4H8] , 315 (46) [M ꢀ CO2C4H8 ꢀ CO2C4H9] , 123 (40)
‡
‡
‡
‡
‡
(16) [M ꢀ CO2C4H8] , 316 (100) [M ꢀ 2 Â CO2C4H8] , 57 (41) [C4H9] ;
[C8H13N] , 57 (100) [C4H9] ; C32H40N2O4 (516.7): HMRS calcd 516.2988;
found 516.2988.
C32H40N2O4 (516.7): HMRS calcd 516.2988; found 516.2988.
(E,E)-1,4-Bis-[2'-(1''-tert-butoxycarbonyl-[1''H]-pyrrol-2''-yl)-vinyl]-ben-
zene (6a): According to general procedure IIa the vinylpyrrole 3a (483 mg,
2.50 mmol, 1.3 equiv) was reacted with 1,4-diiodobenzene (4b, 330 mg,
1.00 mmol, 1.0 equiv) for 20 h at 708C. Column chromatography (40 g silica
gel, eluent 2) afforded 6a (170 mg, 369 mmol, 37%) as yellow crystals. M.p.
(E,E)-1,4-Bis-[2'-(1''-tert-butoxycarbonyl-3'',4''-dimethyl-5''-ethoxycarbon-
yl-[1H]-pyrrol-2''-yl)-vinyl]-benzene (10b): According to general proce-
dure IIb the iodopyrrole 8 (708 mg, 1.80 mmol, 1.5 equiv) was treated with
1,4-divinylbenzene (9, 78.4 mg, 600 mmol, 1.0 equiv) for 2 h at 758C.
Column chromatography (10 g silica gel, eluent 5) afforded 10b (137 mg,
207 mmol, 35%) as yellow crystals. M.p. 1708C; tR ˆ 0.47 (eluent 3); IR
ꢀ
>1808C (dec); tR ˆ 0.40 (eluent 2); IR (KBr): nÄ ˆ 3004, 2980, 2932 (C H),
ꢀ1
ˆ
ˆ
ꢀ
1738 (C O), 1620, 1652, 1510 (C C), 958 cm (C H, (E)-alkene); UV
(CH3CN): lmax (log e) ˆ 197.0 (4.532), 244.5 (4.138), 377.0 nm (4.685);
1H NMR (300 MHz, CDCl3): d ˆ 1.63 (s, 18H, C(CH3)3), 6.19 (t, J ˆ 3.5 Hz,
2H, 4''-H), 6.56 (m, 2H, 3''-H), 6.87 (d, J ˆ 16.5 Hz, 2H, 1'-H), 7.28 (dd, J ˆ
3.5, 1.5 Hz, 2H, 5'-H), 7.44 (s, 4H, Ph-H), 7.75 (d, J ˆ 16.5 Hz, 2H, 2'-H);
13C NMR (50.3 MHz, CDCl3): d ˆ 28.0 (C(CH3)3), 83.8 (C(CH3)3), 110.7 (C-
4''), 111.1 (C-3''), 119.3 (C-2'), 122.2 (C-5''), 126.6 (C-2, C-3, C-5, C-6), 127.8
ꢀ
ˆ
(KBr): nÄ ˆ 2980, 2936, 2906 (C H), 1746 (carbamate-C O), 1692 (ester-
ꢀ1
ˆ
ˆ
ꢀ
C O), 1564, 1512 (C C), 960 cm (C H, (E)-alkene); UV (CH3CN): lmax
(log e) ˆ 191.0 (4.481), 227.0 (4.144), 377.5 (4.688), 379.5 nm (4.688);
1H NMR (200 MHz, CDCl3): d ˆ 1.37 (t, J ˆ 7.0 Hz, 6H, CO2CH2CH3), 1.58
(s, 18H, C(CH3)3), 2.16 (s, 6H, 4-CH3), 2.23 (s, 6H, 3-CH3), 4.33 (q, J ˆ
7.0 Hz, 4H, CO2CH2CH3), 6.76 (d, J ˆ 17.0 Hz, 2H, 1'-H), 7.31 (d, J ˆ
17.0 Hz, 2H, 2'-H), 7.45 (s, 4H, Ph-H); 13C NMR (50.3 MHz, CDCl3): d ˆ
10.4 (3''-CH3), 11.0 (4''-CH3), 14.4 (CO2CH2CH3), 27.7 (C(CH3)3), 60.5
(CO2CH2CH3), 84.5 (C(CH3)3), 117.9 (C-2'), 120.4, 121.7 (C-3'', C-4''), 126.7
(C-2, C-3, C-5, C-6), 130.2 (C-5''), 132.3 (C-1'), 132.8 (C-2''); 136.8 (C-1,
ˆ
(C-1'), 134.4 (C-2''), 136.7 (C-1, C-4), 149.4 (C O); MS (70 eV): m/z (%):
‡
‡
‡
460 (30) [M] , 404 (8) [M ꢀ C4H8] , 360 (12) [M ꢀ CO2C4H8] , 348 (100)
‡
‡
[M ꢀ 2 Â C4H8] , 304 (37) [M ꢀ CO2C4H8 ꢀ C4H8] , 259 (31) [M ꢀ
‡
‡
CO2C4H8 ꢀ CO2C4H9] , 57 (13) [C4H9] ; C28H32N2O4 (460.6): calcd C
ˆ
ˆ
C-6), 149.9 (carbamate-C O), 161.7 (ester-C O); MS (70 eV): m/z (%):
‡
‡
73.02, H 7.00; found C 73.08, H 7.04.
661 (2) [M] , 561 (7) [M ꢀ CO2C4H8] , 460 (100) [M ꢀ CO2C4H8 ꢀ
‡
‡
CO2C4H9] , 413 (12) [M ꢀ 2 Â CO2C4H9 ꢀ OC2H5] ; C38H48N2O8 (660.8):
(E,E)-1,4-Bis-[2'-(1''-tert-butoxycarbonyl-3'',4''-dimethyl-[1''H]-pyrrol-2''-
yl)-vinyl]-benzene (6b): According to general procedure IIc vinylpyrrole
3b (277 mg, 1.25 mmol, 1.3 equiv) was treated with 1,4-diiodobenzene (4b,
165 mg, 500 mmol, 1.0 equiv) for 4 h at 908C. Column chromatography
(eluent 2) afforded 6b (72.3 mg, 139 mmol, 28%) as yellow crystals. M.p.
calcd C 69.07, H 7.32; found C 68.90, H 7.25.
2-[(E)-2'-(4''-Formylphenyl)-vinyl]-[1H]-1-N-tert-butyloxycarbonyl-pyrrol
(12): According to general procedure IIa the vinylpyrrole 3a (212 mg,
1.10 mmol, 1.1 equiv) was treated with 4-iodobenzaldehyde (11, 232 mg,
1.00 mmol, 1.0 equiv) for 4 h at 908C. Column chromatography (20 g silica
gel, eluent 2) afforded 12 (140 mg, 471 mmol, 47%) as a yellow oil. tR ˆ 0.34
ꢀ
>2008C (dec); tr ˆ 0.49 (eluent 1); IR (KBr): nÄ ˆ 3002, 2974, 2926 (C H),
ꢀ1
ˆ
ˆ
ꢀ
1720 (C O), 1628, 1566, 1506 (C C), 960 cm (C H, (E)-alkene); UV
(CH2Cl2): lmax (log e) ˆ 251.0 (4.122), 372.5 nm (4.536); 1H NMR
(200 MHz, CDCl3): d ˆ 1.58 (s, 18H, C(CH3)3), 2.00 (s, 6H, 4''-CH3), 2.15
(s, 6H, 3''-CH3), 6.59 (d, J ˆ 16.5 Hz, 2H, 1'-H), 7.04 (s, 2H, 5'-H), 7.44 (s,
4H, Ph-H), 7.56 (d, J ˆ 16.5 Hz, 2H, 2'-H); 13C NMR (50.3 MHz, CDCl3):
d ˆ 10.37, 11.36 (3''-CH3, 4''-CH3), 28.16 (C(CH3)3), 83.00 (C(CH3)3), 118.4
(C-5''), 120.1 (C-2'), 122.2, 122.7 (C-3, C-4), 126.3 (C-2, C-3, C-5, C-6), 129.4
ꢀ
(eluent 2); IR (neat): nÄ ˆ 2980, 2934, 2842, 2732 (C H), 1742 (carbamate-
ꢀ1
ˆ
ˆ
ˆ
ꢀ
C O), 1696 (aldehyde-C O), 1598, 1564 (C C), 962 cm (C H, (E)-
alkene); UV (CH3CN): lmax (log e) ˆ 194.0 (4.472), 251.5 (4.042), 360.5 nm
1
(4.346); H NMR (200 MHz, C6D6): d ˆ 1.29 (s, 9H, C(CH3)3), 6.10 (t, J ˆ
3.5 Hz, 1H, 4-H), 6.52 (m, 1H, 3-H), 6.77 (d, J ˆ 16.5 Hz, 1H, 2'-H), 7.26 (d,
J ˆ 8.5 Hz, 2H, 2''-H, 6''-H), 7.32 (dd, J ˆ 3.5, 1.5 Hz, 1H, 5-H), 7.52 (d, J ˆ
8.5 Hz, 2H, 3''-H, 5''-H), 8.17 (d, J ˆ 16.5 Hz, 1H, 1'-H), 9.66 (s, 1H, CHO);
13C NMR (50.3 MHz, CDCl3): d ˆ 27.84 (C(CH3)3), 83.97 (C(CH3)3), 111.2,
111.8 (C-3, C-4), 122.8 (C-1'), 122.9 (C-5), 126.2 (C-2'), 126.4 (C-2'', C-6''),
ˆ
(C-1'), 129.4 (C-2''), 136.9 (C-1, C-4), 149.5 (C O); MS (70 eV): m/z (%):
‡
‡
516 (72) [M] , 404 (99) [M ꢀ 2 Â C4H8] , 315 (100) [M ꢀ CO2C4H8 ꢀ
‡
‡
CO2C4H9] , 57 (13) [C4H9] ; C32H40N2O4 (516.7): HMRS calcd 516.2988;
found 516.2988.
129.9 (C-3'', C-5''), 133.5, 134.8 (C-2, C-4''), 143.6 (C-1''), 149.1 (carbamate-
(E,E)-1,2-Bis-[2'-(1''-tert-butoxycarbonyl-[1''H]-pyrrol-2''-yl)-vinyl]-ben-
zene (7a): According to general procedure IId the vinylpyrrole 3a (483 mg,
2.50 mmol, 1.3 equiv) was treated with 1,2-diiodobenzene (4c, 330 mg,
1.00 mmol, 1.0 equiv) for 20 h at 908C. Column chromatography (eluent 2)
afforded 7a (216 mg, 469 mmol, 47%) as a yellow oil. tR ˆ 0.39 (eluent 2);
‡
ˆ
ˆ
C O), 191.2 (aldehyde-C O); MS (70 eV): m/z (%): 297 (24) [M] , 241
‡
‡
(100) [M ꢀ C4H8] , 197 (61) [M ꢀ CO2C4H8] , 168 (33) [M ꢀ CO2C4H8 ꢀ
‡
‡
CHO] , 57 (78) [C4H9] ; C18H19NO3 (297.4): calcd C 72.71, H 6.44; found C
72.84, H 6.55.
ꢀ
ˆ
ˆ
IR (neat): nÄ ˆ 2978, 2932, 2866 (C H), 1742 (C O), 1616, 1548 (C C),
2-[(E)-2'-(4''-Vinylphenyl)-vinyl]-[1H]-1-N-tert-butyloxycarbonyl-pyrrol
(13): According to general procedure I aldehyde 12 (2.12 g, 7.13 mmol) was
subjected to a Wittig reaction. Column chromatography (100 g silica gel,
eluent 4) afforded compound 13 (1.51 g, 5.11 mmol, 72%) as a pale yellow
958 cmꢀ1 (C H, (E)-alkene); UV (CH3CN): lmax (log e) ˆ 311.0 nm (3.981);
ꢀ
1H NMR (200 MHz, C6D6): d ˆ 1.29 (s, 18H, C(CH3)3), 6.08 (t, J ˆ 3.5 Hz,
2H, 4''-H), 6.50 (m, 2H, 3''-H), 7.05 (dd, J ˆ 6.0, 3.5 Hz, 2H, 4-H, 5-H), 7.34
(dd, J ˆ 3.5, 1.5 Hz, 2H, 5''-H), 7.48 (d, J ˆ 16.0 Hz, 2H, 1'-H), 7.65 (dd, J ˆ
6.0, 3.5 Hz, 2H, 3-H, 6-H), 8.03 (d, J ˆ 16.0 Hz, 2H, 2'-H); 13C NMR
(50.3 MHz, CDCl3): d ˆ 28.02 (C(CH3)3), 83.84 (C(CH3)3), 110.9, 111.0
(C-3'', C-4''), 121.8 (C-2'), 122.2 (C-5''), 125.9, 126.4, 127.4 (C-3, C-4, C-5,
solid. M.p. 778C; tR ˆ 0.57 (eluent 2); IR (KBr): nÄ ˆ 3040, 3002, 2976, 2932
ꢀ1
ꢀ
ˆ
ˆ
ꢀ
(C H), 1744 (C O), 1622, 1602, 1550, 1508 (C C), 966 cm (C H, (E)-
alkene); UV (CH3CN): lmax (log e) ˆ 197.0 (4.502), 240.5 (4.019), 344.5 nm
1
(4.494); H NMR (300 MHz, CDCl3): d ˆ 1.62 (s, 9H, C(CH3)3), 5.23 (dd,
ˆ
C-6, C-1'), 134.6, 135.8 (C-1, C-2, C-2''), 149.4 (C O); MS (70 eV): m/z (%):
ˆ
ˆ
J ˆ 11.0, 1.0 Hz, 1H, trans CH2), 5.74 (dd, J ˆ 18.0, 1.0 Hz, 1H, cis CH2),
6.19 (t, J ˆ 3.5 Hz, 1H, 4-H), 6.56 (m, 1H, 3-H), 6.70 (dd, J ˆ 18.0, 11.0 Hz,
1H, CH ˆ CH2), 6.87 (d, J ˆ 16.5 Hz, 1H, 2'-H), 7.28 (dd, J ˆ 3.5, 1.5 Hz,
1H, 5-H), 7.37, 7.43 (AA'BB'-system, J ˆ 8.0 Hz, 4H, Ph-H), 7.76 (d, J ˆ
16.5 Hz, 1H, 1'-H); 13C NMR (50.3 MHz, CDCl3): d ˆ 28.0 (C(CH3)3), 83.8
‡
‡
‡
460 (44) [M] , 404 (11) [M ꢀ C4H8] , 348 (36) [M ꢀ 2 Â C4H8] , 304 (17)
‡
‡
[M ꢀ CO2C4H8 ꢀ C4H8] , 259 (26) [M ꢀ CO2C4H8 ꢀ CO2C4H9] , 193 (27),
180 (32), 57 (13) [C4H9]; C28H32N2O4 (460.6): calcd C 73.02, H 7.00; found
C 73.00, H 7.00.
ˆ
(E,E)-1,2-Bis-[2'-(1''-tert-butoxycarbonyl-3'',4''-dimethyl-[1''H]-pyrrol-2''-
yl)-vinyl]-benzene (7b): According to general procedure IIc vinyl pyrrole
3b (553 mg, 2.50 mmol, 1.3 equiv) was treated with 1,2-diiodobenzene (4c,
330 mg, 1.00 mmol, 1.0 equiv) for 5h at 908C. Column chromatography
(10 g silica gel, eluent 1) afforded 7b (52.4 mg, 101 mmol, 10%) as a yellow
(C(CH3)3), 110.7 (C-4), 111.1 (C-3), 113.4 (CH CH2), 119.7 (C-1'), 122.3
(C-5), 126.4 (C-2'', C-3'', C-5'', C-6''), 127.7 (C-2'), 134.3 (C-2), 136.4
ˆ
ˆ
(CH CH2), 137.2 (C-1'', C-4''), 149.4 (C O); MS (70 eV): m/z (%): 295 (16)
[M] , 239 (100) [M ꢀ C4H8] , 195 (42) [M ꢀ CO2C4H8] , 57 (32) [C4H9] ;
‡
‡
‡
‡
C19H21NO2 (295.4): HMRS calcd 295.1572; found 295.1572.
Chem. Eur. J. 2001, 7, No. 2
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0702-0371 $ 17.50+.50/0
371

L. F. Tietze et al.
FULL PAPER
1-[(E)-2'-(1''-tert-Butoxycarbonyl-3'',4''-dimethyl-5''-ethoxycarbonyl-
[1''H]-pyrrol-2-yl)-vinyl]-4-[(E)-2'''-(1''''-tert-butoxycarbonyl-[1''''H]-pyr-
rol-2''''-yl)-vinyl]-benzene (10a): According to general procedure IIa the
compound 13 (118 mg, 400 mmol, 1.0 equiv) was treated with the iodopyr-
role (8, 189 mg, 480 mmol, 1.2 equiv) for 2.5 h at 908C. Column chromatog-
raphy (10 g silica gel, eluent 5) afforded 10a (133 mg, 237 mmol, 59%) as a
yellow solid. M.p. 1318C; tR ˆ 0.31 (eluent 2); IR (KBr): nÄ ˆ 3002, 2976,
(E,E)-2,5-Bis-[2'-(4''-vinylphenyl)-vinyl]-[1H]-1-N-tert-butyloxycarbonyl-
pyrrol (18): According to general procedure I the dialdehyde 17 (480 mg,
1.12 mmol) was transformed to the corresponding divinyl compound. Due
to the poor solubility of the substrate it was added as a solution in CH2Cl2.
After warming to room temperature the reaction mixture was stirred for
1.5 h. Column chromatography (20 g silica gel, eluent 6) and subsequent
crystallisation from light petroleum/EtOAc afforded 18 (294 mg, 694 mmol,
62%) as an orange solid. M.p. 1618C; tR ˆ 0.66 (eluent 2); IR (KBr): nÄ ˆ
ꢀ
ˆ
ˆ
2932 (C H), 1744 (carbamate-C O), 1668 (ester-C O), 1624, 1596, 1546,
ꢀ1
ˆ
ꢀ
ꢀ
ˆ
ˆ
1512 (C C), 972, 960 cm (C H, (E)-alkene); UV (CH3CN): lmax (log e) ˆ
242.5 (4.169), 377.0 (4.732), 379.5 nm (4.722); 1H NMR (500 MHz, CDCl3):
d ˆ 1.37 (t, J ˆ 7.0 Hz, 3H, CO2CH2CH3), 1.56 (s, 9H, C(CH3)3''), 1.63 (s,
9H, C(CH3)3''''), 2.14 (s, 3H, 4''-CH3), 2.21 (s, 3 H 3''-CH3), 4.33 (q, J ˆ
7.0 Hz, 2H, CO2CH2CH3), 6.20 (t, J ˆ 3.5 Hz, 1H, 4''''-H), 6.57 (m, 1H, 3''''-
H), 6.76 (d, J ˆ 16.5 Hz, 1H, 1'-H), 6.89 (d, J ˆ 16.5 Hz, 1H, 1'''-H), 7.28 (d,
J ˆ 16.5 Hz, 1H, 2'-H), 7.29 (dd, J ˆ 3.5, 1.5 Hz, 1H, 5''''-H), 7.43, 7.46
(AA'BB'-system, J ˆ 8.5 Hz, 4H, Ph-H), 7.78 (d, J ˆ 16.5 Hz, 1H, 2'''-H);
13C NMR (50.3 MHz, CDCl3): d ˆ 10.4 (3''-CH3), 11.0 (4''-CH3), 14.4
(CO2CH2CH3), 27.7 (C(CH3)3''), 28.1 (C(CH3)3''''), 60.5 (CO2CH2CH3), 83.9
(C(CH3)3''''), 84.4 (C(CH3)3''), 110.8 (C-4''''), 111.2 (C-3''''), 117.5 (C-2'),
119.7 (C-2'''), 120.3, 121.6 (C-3'', C-4''), 122.3 (C-5''''), 126.58, 126.63 (C-2,
C-3, C-5, C-6), 127.6 (C-1'''), 130.2 (C-5''), 132.5 (C-1'), 132.9 (C-2''), 134.3
3078, 3002, 2978, 2932 (C H), 1746 (C O), 1620, 1596, 1552, 1506 (C C),
960 cmꢀ1 (C H, (E)-alkene); UV (CH3CN): lmax (log e) ˆ 198.5 (4.701),
ꢀ
267.0 (4.355), 399.5 nm (4.722); 1H NMR (200 MHz, CDCl3): d ˆ 1.66
ˆ
(C(CH3)3), 5.27 (dd, J ˆ 11.0, 0.5 Hz, 2H, trans CH2), 5.75 (dd, J ˆ 17.5,
ˆ
0.5 Hz, 2H, cis CH2), 6.57 (s, 2H, 3-H, 4-H), 6.71 (dd, J ˆ 17.5, 11.0 Hz, 2H,
ˆ
CH CH2), 6.86 (d, J ˆ 16.5 Hz, 2H, 2'-H), 7.27 (AA'BB'-system, J ˆ 8.0 Hz,
4H, Ph-H), 7.53 (d, J ˆ 16.5 Hz, 2H, 1'-H); 13C NMR (50.3 MHz, CDCl3):
ˆ
d ˆ 28.2 (C(CH3)3), 84.6 (C(CH3)3), 111.0 (C-3, C-4), 113.4 (CH CH2),
119.9 (C-1'), 126.3, 126.5 (C-2'', C-3'', C-5'', C-6''), 127.3 (C-2'), 135.6 (C-2,
ˆ
ˆ
C-5), 136.4 (CH CH2), 136.5, 137.2 (C-1'', C-4''), 150.0 (C O); MS (70 eV):
‡
‡
‡
m/z (%): 423 (26) [M] , 367 (100) [M ꢀ C4H8] , 323 (94) [M ꢀ CO2C4H8] ,
‡
57 (24) [C4H9] ; C29H29NO4 (423.6): calcd C 82.24, H 6.90; found C 82.11, H
6.83.
ˆ
(C-2''''), 136.2, 137.3 (C-1, C-4), 149.5 (1''''-carbamate-C O), 149.9 (1''-
(E,E)-2,5-Bis-[2'-(4''-((E)-2'''-(1''''-tert-butoxycarbonyl-5''''-ethoxycarbon-
yl-3'''',4''''-dimethyl-[1''''H]-pyrrol-2''''-yl)-vinyl)-phenyl)-vinyl]-[1H]-1-N-
tert-butyloxycarbonyl-pyrrol (19): According to general procedure IIb the
compound 18 (169 mg, 400 mmol, 1.0 equiv) was treated with the iodopyrrole
8 (472 mg, 400 mmol, 1.0 equiv) for 2 h at 758C. Column chromatography
(10 g silica gel, eluent 5) and recrystallisation from Et2O afforded 19
(107 mg, 112 mol, 28%) as red crystals. M.p. 1638C; tR ˆ 0.41 (eluent 3); IR
‡
ˆ
ˆ
carbamate-C O), 161.7 (ester-C O); MS (70 eV): m/z (%): 561 (24) [M] ,
‡
‡
461 (16) [M ꢀ CO2C4H8] , 404 (9) [M ꢀ CO2C4H8 ꢀ C4H9] , 360 (100) [M ꢀ
‡
‡
CO2C4H8 ꢀ CO2C4H9] , 313 (40) [M ꢀ 2 Â CO2C4H9 ꢀ OC2H5] , 56 (55)
‡
‡
[C4H8] , 41 (87) [C3H5] ; C33H40N2O6 (560.7): calcd C 70.69, H 7.19; found
C 70.61, H 7.33.
(E,E)-1,3-Bis-[2'-(4''-((E)-2'''-(1''''-tert-butoxycarbonyl-[1''''H]-pyrrol-2''''-
yl)-vinyl)-phenyl)-vinyl]-benzene (14): According to general procedure
IIb, 13 (443 mg, 1.50 mmol, 1.5 equiv) was treated with 1,3-diiodobenzene
(4, 165 mg, 500 mmol, 1.0 equiv) for 3 h at 708C. Extraction was performed
with CH2Cl2. Column filtration (silica gel, CHCl3) of the poorly soluble
residue gave an orange solid, which for further purification was absorbed
on silica gel (40 g silica gel). After the silica gel was washed with light
petroleum/EtOAc 10:1 to 1:1, 14 was eluated with warm CHCl3 to give an
orange solid (257 mg, 387 mmol, 77%) after evaporation in vacuo. M.p.
ꢀ
ˆ
(KBr): nÄ ˆ 3076, 2978, 2934 (C H), 1742 (carbamate-C O), 1704 (ester-
ꢀ1
ˆ
ˆ
ꢀ
C O), 1618, 1594, 1556, 1510 (C C), 954 cm (C H, (E)-alkene); UV
(CH3CN): lmax (log e) ˆ 197.0 (4.657), 251.0 (4.282), 328.0 (4.265), 431.0 nm
(4.858); 1H NMR (300 MHz, C6D6): d ˆ 1.08 (t, J ˆ 7.0 Hz, 6H,
CO2CH2CH3), 1.34 (s, 9H, C(CH3)3, 1.46 (s, 18H, C(CH3)3''''), 1.93 (s,
6H, 4''''-CH3), 2.20 (s, 6H, 3''''-CH3), 4.17 (q, J ˆ 7.0 Hz, 4H, CO2CH2CH3),
6.55 (s, 2H, 3-H, 4-H), 6.79 (d, J ˆ 16.5 Hz, 2H, 1'''-H), 6.93 (d, J ˆ 16.0 Hz,
2H, 2'-H), 7.40 (s, 8H, Ph-H), 7.65 (d, J ˆ 16.5 Hz, 2H, 2'''-H), 7.86 (d, J ˆ
16.0 Hz, 2H, 1'-H); 13C NMR (75.5 MHz, CDCl3): d ˆ 10.44 (3''''-CH3),
10.97 (4''''-CH3), 14.42 (CO2CH2CH3), 27.66 (C(CH3)3''''), 28.23 (C(CH3)3),
60.49 (CO2CH2CH3), 84.45 (C(CH3)3''''), 84.75 (C(CH3)3), 111.1 (C-3, C-4),
117.6 (C-2'''), 120.0 (C-1'), 120.4, 121.6 (C-3'''', C-4''''), 126.6, 126.7 (C-2'',
C-3'', C-5'', C-6''), 127.3 (C-2'), 130.3 (C-5''''), 132.5 (C-1'''), 133.0 (C-2''''),
>2008C (dec); tR ˆ 0.29 (eluent 2); IR (KBr): nÄ ˆ 3078, 3024, 2978, 2932
ꢀ1
ꢀ
ˆ
ˆ
ꢀ
(C H), 1740 (C O), 1618, 1590, 1510 (C C), 960 cm (C H, (E)-alkene);
UV (CH2Cl2): lmax (log e) ˆ 246.0 (4.412), 377.5 (4.967), 379.5 nm (4.967);
1H NMR (500 MHz, CDCl3): d ˆ 1.64 (s, 18H, C(CH3)3), 6.20 (t, J ˆ 3.5 Hz,
2H, 4''''-H), 6.58 (ddd, J ˆ 3.5, 1.5, 1.0 Hz, 2H, 3''''-H), 6.90 (d, J ˆ 16.0 Hz,
2H, 1'''-H), 7.14, 7.15 (AB-system, J ˆ 16.5 Hz, 1'-H, 2'-H), 7.29 (dd, J ˆ 3.5,
1.5 Hz, 5''''-H), 7.36 (dd, J ˆ 8.0, 6.5 Hz, 1H, 5-H), 7.41 ± 7.44 (m, 2H, 4-H,
6-H), 7.49, 7.51 (AA'BB'-system, J ˆ 8.0 Hz, 8H, Ph-H), 7.66 (s, 1H, 2-H),
7.79 (d, J ˆ 16.0 Hz, 2H, 2'''-H); 13C NMR (75.5 MHz, CDCl3): d ˆ 28.2
(C(CH3)3), 83.9 (C(CH3)3), 110.9, 111.2 (C-3'''', C-4''''), 119.9 (C-2'''), 122.4
(C-5''''), 124.8 (C-2), 125.7 (C-4, C-6), 126.8, 126.9 (C-2'', C-3'', C-5'', C-6''),
127.8, 128.3, 128.9 (C-1', C-2', C-1'''), 129.0 (C-5), 134.6 (C-2''''), 136.5, 137.4,
ˆ
135.7 (C-2, C-5), 136.3, 137.3 (C-1'', C-4''), 149.4 (1''''-carbamate-C O),
ˆ
ˆ
150.1 (1-carbamate-C O), 161.7 (ester-C O); MS (FAB, positive): m/z
‡
‡
‡
(%): 953 (100) [M] , 897 (8) [M ꢀ C4H8] , 854 (20) [M ꢀ CO2C4H8‡H] ,
‡
‡
754 (13) [M ꢀ 2  CO2C4H8‡H] , 697 (7) [M ꢀ 2  CO2C4H8 ꢀ C4H8] , 653
‡
(93) [M ꢀ 3 Â CO2C4H8] , 607 (14) [M ꢀ 2 Â CO2C4H8 ꢀ CO2C4H9 ꢀ
‡
‡
OC2H5] , 560 (9) [M ꢀ 3 Â CO2C4H9 ꢀ 2 Â OC2H5] ; C57H67N3O10 (954.2):
calcd C 71.75, H 7.08; found C 71.90, H 7.00.
‡
138.0 (C-1, C-3, C-1'', C-4''); MS (DCI, NH3): m/z (%): 666 (100) [M‡H] ,
‡
‡
667 (40) [M‡2H] , 683 (4) [M‡NH4] ; C44H44N2O4 (664.84): calcd C 79.49,
Acknowledgement
H 6.67; found C 79.50, H 6.67.
(E,E)-2,5-Bis-[2'-(4''-formylphenyl)-vinyl]-[1H]-1-N-tert-butyloxycarbon-
yl-pyrrol (17): According to general procedure IIb 4-vinylbenzaldehyde 16
(792 mg, 6.0 mmol, 2.0 equiv) was treated with the diiodopyrrole 15
(692 mg, 1.50 mol, 1.0 equiv) for 2 h at 608C. Extraction was performed
with CH2Cl2. Column filtration (15 g deactivated silica gel, CH2Cl2) of the
crude reaction mixture was followed by recrystallisation from CH2Cl2/light
petroleum to yield 17 (417 mg, 975 mmol, 67%) as orange crystals. M.p.
>1708C (dec); tR ˆ 0.25 (light petroleum/EtOAc 4:1); IR (KBr): nÄ ˆ 3030,
This research was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie. We thank the BASF AG, Bayer AG,
Degussa-Hüls AG and the Wacker Chemie for the gift of chemicals.
[1] a) F. Blanche, B. Cameron, J. Crouzet, L. Debussche, D. Thibaut, M.
Vuilhorgne, F. J. Leeper, A. R. Battersby, Angew. Chem. 1995, 107,
421; Angew. Chem. Int. Ed. Engl. 1995, 34, 383; b) The Biosynthesis of
Tetrapyrrole Pigments, Ciba Foundation Symposia, Vol. 180 (Eds.:
D. J. Chadwick, K. Ackrill), Wiley, Chichester, 1994; c) Biosynthesis of
Tetrapyrroles (Ed.: P. M. Jordan), Elsevier Publishers, Amsterdam,
1990; d) A. I. Scott, Tetrahedron 1994, 50, 13315; e) L. F. Tietze, G.
Schulz, Chem. Eur. J. 1997, 3, 523; f) L. F. Tietze, H. Geissler, G.
Schulz, Pure Appl. Chem. 1994, 66, 2303; g) L. F. Tietze, H. Geissler,
Angew. Chem. 1993, 105, 1087; Angew. Chem. Int. Ed. Engl. 1993, 32,
1038; h) L. F. Tietze, H.Geissler, Angew. Chem. 1993, 105, 1090;
Angew. Chem. Int. Ed. Engl. 1993, 32, 1040.
ꢀ
ˆ
3004, 2974, 2934, 2822, 2728 (C H), 1734 (carbamate-C O), 1690
ꢀ1
ˆ
ˆ
ꢀ
(aldehyde-C O), 1592, 1562 (C C), 960 cm (C H, (E)-alkene); UV
(CH3CN): lmax (log e) ˆ 195.0 (4.632), 264.0 (4.299), 419.0 nm (4.684);
1H NMR (200 MHz, CDCl3): d ˆ 1.69 (s, 9H, C(CH3)3), 6.67 (s, 2H, 3-H,
4-H), 6.93 (d, J ˆ 16.5 Hz, 2H, 2'-H), 7.59 (d, J ˆ 8.0 Hz, 4H, 2''-H, 6''-H),
7.73 (d, J ˆ 16.5 Hz, 2H, 1'-H), 7.85 (d, J ˆ 8.0 Hz, 4H, 3''-H, 5''-H), 9.99 (s,
2H, CHO); 13C NMR (50.3 MHz, CDCl3): d ˆ 28.2 (C(CH3)3), 85.3
(C(CH3)3), 112.2 (C-3, C-4), 123.0 (C-1'), 126.5 (C-2'', C-6''), 126.7 (C-2'),
ˆ
130.2 (C-3'', C-5''), 135.0, 135.6 (C-2, C-5, C-4''), 143.5 (carbamate-C O),
‡
ˆ
191.4 (aldehyde-C O); MS (70 eV): m/z (%): 427 (24) [M] , 371 (100)
‡
‡
‡
[M ꢀ C4H8] , 327 (77) [M ꢀ CO2C4H8] , 57 (21) [C4H9] ; C27H25NO4
[2] a) B. Franck, A. Nonn, Angew. Chem. 1995, 107, 1941; Angew. Chem.
Int. Ed. Engl. 1995, 34, 1795; b) M. Bröring, H.-J. Dietrich, J. Dörr, G.
(427.5): calcd C 75.86, H 5.89; found C 75.86, H 5.92.
372
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0947-6539/01/0702-0372 $ 17.50+.50/0
Chem. Eur. J. 2001, 7, No. 2

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Â
Á
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Received: May 16, 2000 [F2491]
Chem. Eur. J. 2001, 7, No. 2
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