Bis-picket-fence corroles

Article abstract of DOI:10.1016/j.jorganchem.2008.04.039

Superstructured corrole ligands related to the picket-fence porphyrins were obtained from (2,6-dichlorophenyl)dipyrromethane in two steps. Condensation with an aryl aldehyde followed by oxidative ring closure yields A₂B corroles with four perip

Full text of DOI:10.1016/j.jorganchem.2008.04.039

Journal of Organometallic Chemistry 694 (2009) 1011–1015
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Bis-picket-fence corroles
*
Martin Bröring , Carsten Milsmann, Silke Ruck, Silke Köhler
Fachbereich Chemie der Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Superstructured corrole ligands related to the picket-fence porphyrins were obtained from (2,6-dichloro-
phenyl)dipyrromethane in two steps. Condensation with an aryl aldehyde followed by oxidative ring clo-
sure yields A2B corroles with four peripheral bromine atoms. Palladium-catalyzed fourfold amidation at
these positions results in the formation of the desired sterically encumbered species, accompanied
mainly by disubstituted by-products. The insertion of iron ions into the blocked cavity of the new corrole
ligands proves successful when directed towards the nitrosyl derivative. The X-ray crystallographic
investigation of such an iron complex allows a detailed view of the steric restraints imposed by the bulky
amido substituents.
Received 7 February 2008
Received in revised form 24 April 2008
Accepted 28 April 2008
Available online 6 May 2008
Dedicated to Christoph Elschenbroich on the
occasion of his 70th anniversary.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords:
Corroles
Porphyrinoids
Pd catalysis
Iron
NO ligand
Chiral ligands
1. Introduction
Recently, Zhang et al. introduced the palladium-catalyzed ami-
dation reaction as a new method for the preparation of sterically
Over the last few years the chemistry of corroles, one-carbon
short relatives of porphyrin (Fig. 1), and their metal complexes
has been a fast growing field of research stimulated by their
intriguing electronic structures and their numerous potential
applications [1–14]. The basis for this development was provided
by the introduction of new straightforward syntheses for meso-
arylsubstituted corroles [15–21]. Besides the possibility of elec-
tronic fine-tuning of the macrocycle these methods allow the
introduction of reactive groups in the periphery for further func-
tionalization at the meso- and b-positions [20,22–25]. Despite the
general interest in such species, in particular in sterically encum-
bered triarylcorroles, for bioinorganic model compounds or corrole
based catalysts their synthesis has remained a great challenge [26–
28]. Examples for corroles bearing groups larger than chlorine
atoms or methyl groups in the 2- and 6-positions of the meso-sub-
stituents are rare. Collman and Decréau reported the syntheses of
several single-sided hindered corroles [29]. To the best of our
knowledge, the only example for a double-faced protected corrole
so far was reported by Rose and Andrioletti [30]. Both groups used
nitro-substituted triarylcorroles as starting material for their syn-
theses in analogy to the established methods developed for steri-
cally demanding porphyrins [31].
encumbered porphyrins starting from 5,15-bis(2,6-dibromophe-
nyl)porphyrin [32]. Using a catalytic system developed by Buch-
wald et al. [33,34] the desired amidophenylporphyrins were
obtained in high yields. Herein, we report the application of
5,15-bis(2,6-dibromophenyl)corroles as versatile synthons for the
syntheses of both, single-sided and double-sided superstructured
corroles.
2. Results and discussion
2.1. Preparation of bis-picket-fence corroles
A series of five new 5,15-bis(2,6-dibromophenyl)corroles 2a–e
with different meso-aryl substituents at the 10-position was pre-
pared via a [2 + 1] approach developed by Gryko [19]. Starting from
dipyrromethane 1 and the appropriate benzaldehydes, corroles
2a–e were obtained in good yields (Scheme 1). All compounds
were characterized by UV–Vis and 1H NMR spectroscopy as well
as HRMS.
The reaction of corrole 2a with pivalamide 3a was chosen for
optimizing the coupling reaction. The initial attempt to use Zhang’s
conditions developed for the corresponding porphyrins (40 mol%
Pd(OAc)2 based on the amount of corrole 2a) [32] yielded only
trace amounts of the desired tetrasubstituted product 4a. Further-
more, neither the starting material 2a nor additional coupling
* Corresponding author. Tel.: +49 6421 282 5418; fax: +49 6421 282 5653.
E-mail address: Martin.Broering@chemie.uni-marburg.de (M. Bröring).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.04.039

1012
M. Bröring et al. / Journal of Organometallic Chemistry 694 (2009) 1011–1015
increase of the yield of 4a to 30% was obtained by increasing the
reaction temperature to 125 °C. The disubstituted corrole 5a was
unambiguously characterized as the
-atropisomer by 1H NMR
a,a
spectroscopy. The surprising selectivity of the formation of this iso-
mer suggests a strong cooperativity of more than one palladium
atom during the coupling step. However, the nature of this cooper-
ativity has not been discovered, yet.
Corroles 2a–e were coupled with pivalamide 3a using the opti-
mized procedure from above (Table 1). In all the cases, the forma-
tion of di-, tri- and the desired tetra-substituted products 4a–e,
5a–e and 6a–e was observed in comparable relative amounts ex-
cept for the cyano derivative 2d (entry 4 in Table 1) which reacts
sluggishly and thus produces larger amounts of the di- and tri-
substituted byproducts 5d and 6d. In addition, the chiral corroles
4f and 5f have been prepared from the cyclopropylamide 3b in
41% and 21% yield, respectively. The increase in yield compared
to corrole 4a is most likely due to the reduced steric bulk of 3b.
These tetrapyrroles are rare examples for chiral corroles, and in
particular the tetrasubstituted 4f is of interest as ligand for enan-
tioselective catalysis using metallocorroles [27,35–38].
Fig. 1. Tetraphenylporphyrin and triphenylcorrole.
2.2. Nitrosyl iron chelate 7
Despite the steric encumbrance imposed by two bulky pivalam-
ido substituents on each side of the corrole plane the insertion of
iron into the N4 cavity of the macrocycle 4a was performed easily
by a standard protocol [39]. Furthermore, in situ treatment of the
primarily formed iron complex with sodium nitrite resulted in
the immediate formation of the stable nitrosyliron complex 7
which was isolated in an excellent yield of 75% (Scheme 2). The
compound was unambiguously characterized as a typical nitrosyl-
iron corrole [39–42] containing a linear {FeNO}6 unit [43]. In addi-
tion, a characteristic high field shift of the tert-butyl proton signals
in the 1H NMR spectrum of 7 to 0.78 and 0.50 ppm revealed that
the bulky groups are oriented towards the central iron ion and thus
form protected binding pockets on both sides of the tetrapyrrole
plane. This feature of the new functional ligands is very similar
to the scenario found for the parent picket fence porphyrins
[44,45]. A single crystal X-ray crystallographic analysis was under-
taken in order to visualize and further characterize the binding
pocket of 7. Fig. 2 presents the result of this study.
The orientation of the pivalamido substituents in 7 directly
Scheme 1. Synthesis of sterically demanding bis-picket-fence corroles; for R1 see
Table 1.
above and below the tetrapyrrole
p system was confirmed for
the crystalline state. The tert-butyl groups on either side of the
macrocyclic plane are situated about 2.5 Å apart from each other.
As shown in Fig. 1 this scenario results in the formation of two
groove-like pockets, one of which being occupied by the axial NO
ligand. With minimum distances N5–Ht-Bu and O1–Ht-Bu of 2.805
and 2.663 Å, respectively, the slim and almost linearly coordinated
NO ligand (Fe–N5–O1 170.63°; Fe–N5 1.646 Å; N5–O1 1.156 Å)
does not fill the empty space above the iron atom entirely. There-
fore, it can be expected that sufficient space remains within the
products could be found. A palladium(II) induced oxidative degra-
dation of the corrole macrocycle was suspected to account for this
failure. Consequently, the amount of Pd(OAc)2 was reduced to
10 mol%, which resulted in an increase of the yield for 4a to 6%.
In addition, two previously unobserved species were isolated in
72% and 18% yield, and could be identified as the disubstituted
(5a) and trisubstituted (6a) triarylcorrole, respectively. A further
Table 1
Syntheses of sterically demanding corrolesa
Entry
R1
2
3
5: yield (%)b
6: yield (%)b
4: yield (%)b
1
2
3
4
5
6
3,4,5-(OMe)3C6H2
4-MeC6H4
Ph
4-NCC6H4
4-NO2C6H4
3,4,5-(OMe)3C6H2
2a
2b
2c
2d
2e
2a
3a
3a
3a
3a
3a
3b
5a: 41
5b: 40
5c: 36
5d: 63
5e: 49
5f: 21
6a: 13
6b: 19
6c: 18
6d: 15
6e: 16
6f: n. i.
4a: 30
4b: 24
4c: 23
4d: 6
4e: 24
4f: 41
a
Reactions were carried out in THF under Argon with 1.0 equiv. of 2, 4.0 equiv. of 3, 10 mol% Pd(OAc)2 and 20 mol% Xantphos in the presence of 2 equiv. of Cs2CO3 at
125 °C.
b
Isolated yields.

M. Bröring et al. / Journal of Organometallic Chemistry 694 (2009) 1011–1015
1013
coordination chemistry and application of these fascinating new
non-natural porphyrinoids in catalysis and as protein analogues
are currently under way.
3. Experimental
3.1. General remarks
NMR spectra (1H, 13C for 7) were obtained at ambient tempera-
ture on an instrument Bruker ARX 300. Chemical shifts are given in
ppm relative to the residual proton resonance of the solvent. High
resolution mass spectra were recorded using the ESI method on a
Finnigan TSQ 700. UV–Vis spectra were measured on a Shimadzu
UV-1601 PC spectrometer in concentrations of about 10À5 mol/L.
IR spectra were recorded in nujol film on a Bruker Vector 22 instru-
ment. All reactions were performed in an inert atmosphere of ar-
gon by using standard Schlenk techniques and vacuum-line
methods. Solvents were dried and distilled under nitrogen prior
to use. Column chromatography was carried out under nitrogen
using silica (particle size 0.063–0.200 nm). Free base corroles were
purified using the DCVC method [46] on silica PF 60 (Merck) as the
stationary phase. Chemicals were obtained from commercial
sources and used as received.
Scheme 2. One-pot preparation of nitroso iron corrole 7.
3.2. Crystal structure determination
Data of 7 were collected at 173 K on a STOE IPDS2 diffractome-
ter with Mo Ka radiation, k = 0.71073 Å. The structure was solved
by direct methods using SHELXS [47] and refined by full-matrix
least-squares procedures (SHELXL [48]). Disorder models were ap-
plied for two of the t-Bu groups as well as for the FeNO subunit.
A heavily disordered solvent molecule was treated with the SQUEEZE
function as implemented in PLATON [49]. Crystal data for 7: triclinic,
ꢀ
space group P1, a = 14.0095(10), b = 14.5716(11), c = 17.6620(14) Å,
a
= 75.646(6)°, b = 86.984(6)°,
Z = 2, R1 = 0.0703, wR2 = 0.2106 (for 16,727
= 1.165 g cmÀ3
reflections, Io > 2 (Io)).
c
= 63.670(5)°, V = 3123.8(4) Å3,
q
,
r
3.3. Syntheses of the compounds
3.3.1. Preparation and analyses for 1
A solution of 2,6-dibromobenzaldehyde [50] (6.5 g, 24.6 mmol)
in pyrrole (170 mL, 2.5 mol) was purged with argon for 30 min and
treated under stirring with magnesiumbromide-etherate (2.26 g,
12.5 mmol) for 2 h at ambient temperature. Finely ground NaOH
(4.33 g, 0.1 mol) is then added and stirring continued for 45 min.
The solution is kept unstirred for 2 h and carefully filtered through
a plug of silica in order to remove all solids. The filter cake is
washed with additional pyrrole, and the filtrates concentrated in
vacuo at 65 °C until all pyrrole is completely removed. The dark
residue is first chromatographed on silica with n-hexane/ethyl ace-
tate (7/3) and the product fraction finally recrystallized from etha-
nol/water (4/1) to yield the title compound (4.2 g, 45%) as a slightly
yellow solid.
Fig. 2. Truncated views of the molecular structure of 7 illustrating the seating of the
NO ligand within the binding pocket of the bis-picket-fence corrole (ellipsoids set to
50% probability; space-fill model used for pivalamido groups; 10-(3,4,5-trime-
thoxyphenyl) substituent as well as opposite pivalamido groups removed for cla-
rity). Selected bond lengths/Å and angles/°: Fe–N1 1.906(2), Fe–N2 1.888(2), Fe–N3
1.930(2), Fe–N4 1.979(2), Fe–N5 1.647(4), N5–O1 1.155(5); N1–Fe–N2 88.17(9),
N1–Fe–N3 148.35(10), N1–Fe–N4 91.32(8), N1–Fe–N5 104.75(15), N2–Fe–N3 78.-
37(9), N2–Fe–N4 147.17(10), N2–Fe–N5 101.51(14), N3–Fe–N4 85.22(8), N3–Fe–
N5 105.94(15), N4–Fe–N5 110.31(14), Fe–N5–O1 170.7(4).
1H NMR (300 MHz, CDCl3): d = 8.31 (br s, 2H, NH), 7.68 (d, J = Hz,
groove to bind, activate and transfer atoms or small molecules as
required for bioinorganic models as well as stereoselective
catalysts. Preliminary experiments have shown that the cycloprop-
anation of styrene with ethyl diazoacetate occurs in a diastereose-
lective fashion (E/Z 6:1) when catalyzed by 7. In-depth catalytic
studies are currently being undertaken in our laboratories and will
be published elsewhere in due course.
2H, meta-H), 6.97 (t, J = Hz, 1H, para-H), 6.76–6.73 (m, 2H,
a-H),
6.55 (s, 1H, meso-H), 6.23–6.19 (m, 2H, b-H), 6.13–6.08 (m, 2H, b-
H); 13C NMR (75 MHz, CDCl3): d = 139.4, 133.9, 129.3, 129.1,
125.9, 116.8, 108.7, 107.7, 44.6; HRMS-EI (M+): m/z: 379.9346
(calcd for C15H12Br2N2: 379.9347).
3.3.2. General procedure for the synthesis of 10-aryl-5,15-bis(2,6-
dibromophenyl)corroles 2a–e
2,6-Dibromophenyldipyrromethane 1 (250 mg, 0.66 mmol) was
dissolved in 5 mL of a previously prepared solution of TFA (30 lL,
In summary, we have developed a new method for the synthesis
of sterically demanding A2B-corroles starting from readily accessi-
ble 5,15-bis(2,6-dibromophenyl)corroles and shown the favour-
able sterics of these species. Further investigations towards the

1014
M. Bröring et al. / Journal of Organometallic Chemistry 694 (2009) 1011–1015
0.39 mmol) in CH2Cl2 (100 mL). Substituted benzaldehyde
(0.33 mmol) was added and the mixture was stirred at room tem-
perature for 4 h. The reaction mixture was diluted to 10 mL with
CH2Cl2 and slowly added to vigorously stirred CH2Cl2 (150 mL)
simultaneously with a solution of DDQ (195 mg, 0.86 mmol) in
THF (10 mL). The mixture was stirred for further 15 min and evap-
orated to dryness. The crude product was passed over a chroma-
tography column (silica, CH2Cl2/hexane, 4:1). The first, violet
band contained the corrole 2a contaminated with unreacted alde-
hyde. Dry column vacuum chromatography (DCVC) (silica, CH2 Cl2/
hexane, 3:1) of this mixture afforded the pure corrole.
(toluene)/nm 414 (
569 (16), 609 (9.5), 638 (3.6); 409 (97), 567.7 (15), 605.7 (9.7),
638 (5.2), 673 (1.5).
ꢀ
 10À3/dm3 molÀ1 cmÀ1 100), 430 (91),
4a: UV–Vis (CH2Cl2): kmax (lg
(2.95), 643sh (2.78) nm; 1H NMR (300 MHz, CD2Cl2): d = 9.14 (d,
J = 4.3 Hz, H, b-H), 8.79 (d, J = 4.8 Hz, 2H, b-H), 8.71 (d,
e) = 416 (4.99), 568 (3.20), 615
2
J = 4.8 Hz, 2H, b-H), 8.59 (d, J = 4.3 Hz, 2H, b-H), 8.41 (d, J = 8.3 Hz,
4H, meta-H), 7.80 (t, J = 8.3 Hz, 2H, para-H), 7.34 (s, 2H, ortho-H),
7.22 (s, 4H, NH), 4.06 (s, 3 H, para-OCH3), 3.93 (s, 6 H, meta-
OCH3), 0.18 (s, 36H, t-Bu-H); HRMS-ESI ([M+H]+): m/z: 1013.5282
(calcd for C60H69N8O7: 1013.5284).
2a (67.5 mg, 22%). UV–Vis (CH2Cl2): kmax
(
e
rel) = 411 (1.00), 427
5a: UV–Vis (CH2Cl2): kmax (erel) = 415 (1.00), 566 (0.16), 612
(0.79), 569 (0.16), 610 (0.10), 638 (0.05) nm; 1H NMR (300 MHz,
CD2Cl2): d = 9.04 (d, J = 4.2 Hz, 2H, b-H), 8.70 (d, J = 4.7 Hz, 2H, b-
H), 8.52 (d, J = 4.7 Hz, 2H, b-H), 8.41 (d, J = 4.2 Hz, 2H, b-H), 8.03
(d, J = 8.1 Hz, 4H, meta-H), 7.54 (t, J = 8.1 Hz, 2H, para-H), 7.44 (s,
2H, ortho-H), 4.06 (s, 3H, para-OCH3), 3.94 (s, 6H, meta-OCH3);
HRMS-ESI ([M+H]+): m/z: 932.8944 (calcd for C40H29Br4N4O3:
932.8927).
(0.10), 636sh (0.07) nm; 1H NMR (300 MHz, CD2Cl2): d = 9.13–
9.10 (m, 2H, b-H), 8.79–8.75 (m, 2H, b-H), 8.75–8.72 (m, 1H,
meta-H), 8.70–8.63 (m, 2H, b-H), 8.56–8.54 (m, 2H, b-H), 8.46–
8.41 (m, 2H, meta-H), 7.83–7.77 (m, 2H, meta-H + para-H), 7.69 (t,
J = 8.2 Hz, 1H, para-H), 7.42–7.33 (m, 2H, meta-H + NH), 7.31 (s,
1H, NH), 7.24 (s, 1H, NH), 4.06 (s, 3H, OCH3), 3.95 (s, 3H, OCH3),
3.92 (s, 3H, OCH3), 0.21 (s, 9H, t-Bu-H), 0.19 (s, 9 H, t-Bu-H), 0.14
(s, 9H, t-Bu-H); HRMS-ESI ([M+H]+): m/z: 992.3704 (calcd for
C55H59BrN7O6: 992.3705).
2b (50.7 mg, 18%). UV–Vis (CH2Cl2): kmax (erel) = 411 (1.00), 426
(0.77), 570 (0.14), 611 (0.09), 639 (0.05) nm; 1H NMR (300 MHz,
CD2Cl2): d = 9.04 (d, J = 4.2 Hz, 2H, b-H), 8.62 (d, J = 4.7 Hz, 2H, b-
H), 8.52 (d, J = 4.7 Hz, 2H, b-H), 8.41 (d, J =4.2 Hz, 2H, b-H), 8.07
(d, J = 7.9 Hz, 2H, Ph-H), 8.02 (d, J = 8.1 Hz, 4H, meta-H), 7.58–7.50
(m, 4H, Ph-H and para-H), 2.67 (s, 3H, CH 3); HRMS-ESI ([M+H]+):
m/z: 856.8761 (calcd for C38H25Br4N4: 856.8766).
6a: UV–Vis (CH2Cl2): kmax (erel) = 412 (1.00), 564 (0.15), 611
(0.09), 636 (0.06) nm; 1H NMR (300 MHz, CD2Cl2): d = 9.10 (d,
J = 4.3 Hz, 2H, b-H), 8.78-8.73 (m, 4H, b-H + meta-H), 8.63 (d,
J = 4.8 Hz, 2H, b-H), 8.50 (d, J = 4.3 Hz, 2H, b-H), 7.79 (dd,
J = 8.1 Hz, J = 1.2 Hz, 2H, meta-H), 7.68 (t, J = 8.2 Hz, 2H, para-H),
7.54 (d, J = 1.8 Hz, 1H, ortho-H), 7.49 (br s, 4H, NH), 7.30 (d,
J = 1.8 Hz, 1H, ortho-H), 4.06 (s, 3H, –OCH3), 3.98 (s, 3H, –OCH3),
3.91 (s, 3H, –OCH3), 0.17 (s, 18H, t-Bu-H); HRMS-ESI ([M+H]+):
m/z: 973.2106 (calcd for C50H49Br2N6O5: 973.2105).
2c (55.4 mg, 20%). UV–Vis (CH2Cl2): kmax (erel) = 410 (1.00), 425
(0.77), 570 (0.14), 610 (0.09), 639 (0.04) nm; 1H NMR (300 MHz,
CD2Cl2): d = 9.04 (d, J = 4.2 Hz, 2H, b-H), 8.59 (d, J = 4.7 Hz, 2H, b-
H), 8.53 (d, J = 4.7 Hz, 2H, b- H), 8.41 (d, J =4.2 Hz, 2H, b-H), 8.21–
8.17 (m, 2H, Ph-H), 8.03 (d, J = 8.1 Hz, 4H, meta-H), 7.77–7.72 (m,
3H, Ph-H), 7.53 (t, J = 8.1 Hz, 2H, para-H); HRMS-ESI ([M+H]+): m/
z: 842.8597 (calcd for C37H23Br4N4: 842.8610).
3.3.4. Preparation and analyses for 7
Under a blanket of Argon, corrole 4a (20 mg, 20
FeCl2 Â 4H2O (12 mg, 60 mol) are dissolved in 2 mL of metha-
nol/pyridine (2:1) and heated to reflux for 90 min. Saturated aque-
ous sodium nitrite (20 L) is then added and the mixture is heated
lmol) and
2d (59.9 mg, 21%). UV–Vis (CH2Cl2): kmax (erel) = 412 (1.00), 428
(0.81), 570 (0.15), 608 (0.09), 638 (0.03) nm; 1H NMR (300 MHz,
CD2Cl2): d = 9.04 (d, J = 4.2 Hz, 2H, b-H), 8.59 (d, J = 4.8 Hz, 2H, b-
H), 8.55 (d, J = 4.8 Hz, 2H, b-H), 8.44 (d, J = 4.2 Hz, 2H, b-H), 8.35
(d, J = 8.2 Hz, 2H, Ph-H), 8.05 (d, J = 8.2 Hz, 2H, Ph-H), 8.00 (d,
J = 8.1 Hz, 4H, meta-H), 7.49 (t, J = 8.1 Hz, 2H, para-H); HRMS-ESI
([M+H]+): m/z: 867.8583 (calcd for C38H22Br4N5: 867.8562).
l
l
for another 30 min. All volatiles are removed in vacuo and the res-
idue is subjected to column chromatography (neutral alumina II,
methyl-t-butylether). The product elutes in the first red band and
yields a dark red solid after removal of the solvent. Yield: 16 mg
2e (73.0 mg, 25%). UV–Vis (CH2Cl2): kmax (erel) = 411 (1.00),
423sh (0.89), 570 (0.22), 608 (0.12), 639 (0.04) nm; 1H NMR
(300 MHz, CD2Cl2): d = 9.06 (d, J = 4.2 Hz, 2H, b-H), 8.62–8.55 (m,
6H, b-H and Ph-H), 8.44 (d, J = 4.2 Hz, 2H, b-H), 8.40 (d, J =8.8 Hz,
2H, Ph-H), 8.04 (d, J = 8.1 Hz, 4H, meta-H), 7.55 (t, J = 8.1 Hz, 2H,
para-H); HRMS-ESI ([M+H]+): m/z: 887.8450 (calcd for
C37H22Br4N5O2: 887.8466).
(15
lmol, 75%).
7: UV–Vis (CH2Cl2): kmax
(erel) = 373 (1.00), 413 (0.85), 540
(0.24) nm; 1H NMR (300 MHz, CD2Cl2): d = 8.24 (dd, 4J = 0.9 Hz,
3J = 8.1 Hz, 2H, meta-H), 8.13 (d, 3J = 4.8 Hz, 2H, b-H), 8.12 (dd,
4J = 0.9 Hz, 3J = 8.1 Hz, 2H, meta-H), 7.73 (d, 3J = 4.5 Hz, 2H, b-H),
7.66 (d, 3J = 4.8 Hz, 2H, b-H), 7.64 (t, 3J = 8.4 Hz, 2H, para-H), 7.58
(d, 3J = 4.8 Hz, 2H, b-H), 7.38 (bs, 2H, NH), 7.15 (bs, 2H, NHNO),
6.99 (d, 3J = 1.8 Hz, 1H, ortho-H), 6.86 (d, 3J = 1.8 Hz, 1H, ortho-H),
3.93 (s, 3H, para-OCH3), 3.90 (s, 3H, meta-OCH3), 3.81 (s, 3H,
meta-OCH3), 0.78 (s, 18 H, t-BuH), 0.50 (s, 18H, t-BuHNO); 13C
NMR (75 MHz, CD2Cl2): d = 176.1, 175.9, 153.3 (2C), 148.5, 147.2,
146.9, 138.5, 137.3 (4C), 134.0, 133.7, 130.1, 127.4 (2C), 125.9
(2C),125.5 (2C), 121.0, 120.2 (2C), 118.9 (2C), 118.0 (2C), 117.7
(2C), 107.7 (2C), 60.7, 56.3, 56.2, 39.4 (2C), 39.2 (2C), 26.9 (6C),
3.3.3. General procedure for the palladium-catalyzed amidation of
bromo-arylcorroles described for 4a/5a/6a
Corrole 2a (50 mg, 53.6
lmol), pivalinamide 3a (202 mg,
2 mmol), Pd(OAc)2 (1.25 mg, 5.5
lmol), Xantphos (7.5 mg,
12 mmol), and Cs2CO3 (325 mg, 1 mmol) were placed in an oven-
dried resealable Schlenk tube under an argon atmosphere. The
tube was sealed with a Teflon screwcap, evacuated and backfilled
with argon. THF (5 mL) was added via syringe. The tube was sealed
again with the Teflon screwcap and its contents were heated with
stirring. After 65 h at 125 °C, the mixture was cooled to room tem-
perature, taken up in ethyl acetate and concentrated in vacuo. The
crude product was purified by column chromatography (silica,
EtOAc/CH2Cl2, 1:9, then 1:4, then 2:5). Careful chromatography
yielded pure corroles 6aa (21.5 mg, 41%) and 5aa (6.9 mg, 13%)
from the first and second violet band, respectively. The third violet
fraction contained corrole 4aa contaminated with unidentified
products. Pure corrole 4aa was obtained by subsequent DCVC (sil-
ica, EtOAc/CH2Cl2, 5:2) as a purple solid (16.3 mg, 30%).
26.4 (6 C); IR (nujol):
m mNO), 1690 (amide),
(cmÀ1) = 3429, 1776 (
1582, 1500 (amide), 1348, 1296, 1261, 1127, 1055, 1017, 798;
HRMS-ESI ([MÀNO+H]+): m/z: 1066.4398 (calcd for C60H66N8O7Fe:
1066.4417); Anal. calc. (C60H65N9O8Fe): C, 65.75; H, 5.98; N, 11.50.
Found: C, 65.52; H, 5.88; N, 11.35%.
Acknowledgement
Financial support for this work by the Deutsche Forschungs-
gemeinschaft (DFG) is gratefully acknowledged.

M. Bröring et al. / Journal of Organometallic Chemistry 694 (2009) 1011–1015
1015
[19] D.T. Gryko, R. Guilard, G. Canard, J.-M. Barbe, B. Koszarna, S. Brandes, M. Tasior,
Org. Lett. 4 (2002) 4491–4494.
Appendix A. Supplementary data
[20] D.T. Gryko, B. Koszarna, Org. Biomol. Chem. 1 (2003) 350–357.
[21] R. Paolesse, A. Marini, S. Nardis, A. Froiio, F. Mandoj, D.J. Nurco, L. Prodi, M.
Montalti, K.M. Smith, J. Porphyrins Phthalocyanines 7 (2003) 25–36.
[22] D.T. Gryko, B. Koszarna, Synthesis (2004) 2205–2209.
[23] E. Steene, A. Dey, A. Ghosh, J. Am. Chem. Soc. 125 (2003) 16300–16309.
[24] S. Hiroto, I. Hisaka, H. Shinokubo, A. Osuka, Angew. Chem., Int. Ed. 44 (2005)
6763–6766.
CCDC 650380 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2008.04.039.
[25] D.T. Gryko, M. Tasior, T. Peterle, M. Bröring, J. Porphyrins Phthalocyanines 10
(2006) 1360–1370.
[26] Z. Gross, L. Simkhovich, N. Galili, Chem. Commun. (1999) 599–600.
[27] Z. Gross, G. Golubkov, L. Simkhovich, Angew. Chem., Int. Ed. 39 (2000) 4045–
4047.
References
[28] Z. Gross, L. Simkhovich, A. Mahammed, I. Goldberg, Chem. Eur. J. 7 (2001)
1041–1055.
[29] J.P. Collman, R.A. Decreau, Org. Lett. 7 (2005) 975–978.
[30] E. Rose, B. Andrioletti, J. Chem. Soc., Perkin Trans. 1 (2002) 715–716.
[31] J.P. Collman, R.R. Gagne, T.R. Halbert, J.-C. Marchon, C.A. Reed, J. Am. Chem. Soc.
95 (1973) 7868–7870.
[1] R. Paolesse, in: K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The Porphyrin
Handbook, vol. 2, Academic Press, New York, 2000, pp. 201–232.
[2] K.M. Kadish, S. Will, C. Erben, in: K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The
Porphyrin Handbook, vol. 2, Academic Press, New York, 2000, pp. 233–300.
[3] R. Guilard, J.-M. Barbe, C. Stern, K.M. Kadish, in: K.M. Kadish, K.M. Smith, R.
Guilard (Eds.), The Porphyrin Handbook, vol. 18, Elsevier Science, Boston, 2003,
pp. 303–349.
[4] D.T. Gryko, J.P. Fox, D.P. Goldberg, J. Porphyrins Phthalocyanines 8 (2004)
1091–1105.
[5] I. Aviv, Z. Gross, Chem. Commun. (2007) 1987–1999.
[6] W.D. Kerber, B. Ramdhanie, D.P. Goldberg, Angew. Chem., Int. Ed. 46 (2007)
3718–3721.
[7] W.D. Kerber, D.P. Goldberg, J. Inorg. Biochem. 100 (2006) 838–857.
[8] M. Bröring, M. Cordes, S. Köhler, Z. Anorg. Allg. Chem. 634 (2008) 125–130.
[9] M. Bröring, F. Brégier, E. Cónsul Tejero, C. Hell, M.C. Holthausen, Angew. Chem.,
Int. Ed. 46 (2007) 445–448.
[10] M. Bröring, C. Hell, M. Steiner, C.D. Brandt, Z. Anorg. Allg. Chem. 633 (2007)
1082–1086.
[11] M. Bröring, C. Hell, C.D. Brandt, Chem. Commun. (2007) 1861–1862.
[12] M. Bröring, C. Hell, C.D. Brandt, E. Cónsul Tejero, J. Porphyrins Phthalocyanines
7 (2003) 214–219.
[13] J. Harmer, S. van Doorslaer, I. Gromov, M. Bröring, G. Jeschke, A. Schweiger, J.
Phys. Chem. B 106 (2002) 2801–2811.
[32] X.P. Zhang, Y. Chen, K.B. Fields, J. Am. Chem. Soc. 126 (2004) 14718–14719.
[33] S.L. Buchwald, J. Yin, Org. Lett. 2 (2000) 1101–1104.
[34] S.L. Buchwald, J. Yin, J. Am. Chem. Soc. 124 (2002) 6043–6048.
[35] Z. Gross, N. Galili, Angew. Chem., Int. Ed. Engl. 38 (1999) 2366–2369.
[36] L. Simkhovich, P. Iyer, I. Goldberg, Z. Gross, Chem. Eur. J. 8 (2002) 2595–2601.
[37] I. Saltsman, I. Goldberg, Z. Gross, Tetrahedron Lett. 44 (2003) 5669–5673.
[38] A. Mahammed, Z. Gross, J. Am. Chem. Soc. 127 (2005) 2883–2887.
[39] K.M. Kadish, M. Gross, E. Vogel, M. Autret, S. Will, E.V. Caemelbecke, J. Lex, J.-P.
Gisselbrecht, J. Am. Chem. Soc. 116 (1994) 9141–9149.
[40] L. Simkhovich, I. Goldberg, Z. Gross, Inorg. Chem. 41 (2002) 5433–5439.
[41] P.C. Ford, A.J. Crisjoe, J. Am. Chem. Soc. 127 (2005) 6737–6743.
[42] P.C. Ford, C.A. Joseph, M.S. Lee, A.V. Iretskii, Inorg. Chem. 45 (2006) 2075–2082.
[43] J.H. Enemark, R.R. Feltham, Coord. Chem. Rev. 13 (1974) 339–406.
[44] M. Momenteau, C.A. Reed, Chem. Rev. 94 (1994) 659–698.
[45] J.P. Collman, R. Boulatov, C.J. Sunderland, L. Fu, Chem. Rev. 104 (2004) 561–
588.
[46] D.S. Pedersen, C. Rosenbohm, Synthesis (2001) 2431–2434.
[47] G.M. Sheldrick, SHELXS-97
Structure, Universität Göttingen, Germany, 1997.
[48] G.M. Sheldrick, SHELXL-97 Program for Crystal Structure Refinement,
– A Program for Automatic Solution of Crystal
[14] M. Bröring, C. Hell, Chem. Commun. (2001) 2336–2337.
[15] Z. Gross, N. Galili, I. Saltsman, Angew. Chem., Int. Ed. 38 (1999) 1427–1429.
[16] R. Paolesse, L. Jaquinod, D.J. Nurco, S. Mini, F. Sagone, T. Boschi, K.M. Smith,
Chem. Commun. (1999) 1307–1308.
[17] D.T. Gryko, Chem. Commun. (2000) 2243–2244.
[18] R. Paolesse, S. Nardis, F. Sagone, R.G. Khoury, J. Org. Chem. 66 (2001) 550–556.
–
A
Universität Göttingen, Germany, 1997.
[49] A.L. Spek, Acta Crystallogr., Sect. A 46 (1990) c34.
[50] J. Serwatowski, S. Lulinski, J. Org. Chem. 68 (2003) 5384–5387.