Synthesis of nickel(II) azacorroles by Pd-catalyzed amination of α,α'-dichlorodipyrrin NiII complex and their properties

Article abstract of DOI:10.1002/chem.201200485

Synthesis of nickel(II) complexes of meso-aryl-substituted azacorroles was performed by Buchwald-Hartwig amination of a dipyrrin Ni^II complex with benzylamine through C-N and C-C coupling. The highly planar structure of Ni^II azacorroles was elucidated by X-ray diffraction analysis. ¹H NMR analysis and nucleus independent chemical shift (NICS) calculation on Ni^II azacorrole revealed its distinct aromaticity with [17]triaza-annulene 18π conjugation. In addition, acylation of azacorrole selectively afforded N- and C-acylated azacorroles depending on the reaction conditions, showing the dual reactivity of azacorroles. Copyright

Full text of DOI:10.1002/chem.201200485

FULL PAPER
DOI: 10.1002/chem.201200485
Synthesis of Nickel(II) Azacorroles by Pd-Catalyzed Amination of a,a’-
Dichlorodipyrrin NiII Complex and Their Properties
Miki Horie, Yosuke Hayashi, Shigeru Yamaguchi, and Hiroshi Shinokubo*[a]
Abstract: Synthesis of nickel(II) com-
plexes of meso-aryl-substituted azacor-
roles was performed by Buchwald–
Hartwig amination of a dipyrrin NiII
1H NMR analysis and nucleus inde-
pendent chemical shift (NICS) calcula-
tion on NiII azacorrole revealed its dis-
tinct aromaticity with [17]triaza-annu-
lene 18p conjugation. In addition, acy-
lation of azacorrole selectively afforded
N- and C-acylated azacorroles depend-
ing on the reaction conditions, showing
the dual reactivity of azacorroles.
À
complex with benzylamine through C
Keywords: amination · aromaticity ·
À
N and C C coupling. The highly planar
À
C C coupling · palladium · por-
structure of NiII azacorroles was eluci-
dated by X-ray diffraction analysis.
phyrinoids
Introduction
Introduction of one nitrogen atom at the meso-position of
free-base corrole allowed us to draw two possible tautomer-
ic structures of type I and type II (see below; the bold lines
indicate the aromatic 18p-conjugation circuit, Scheme 1).
The former has three inner NH protons and an imine-type
outer nitrogen atom, which is a part of an [18]diaza-annu-
lene structure. In contrast, the latter has two inner NH pro-
tons and the outer nitrogen is amine type, lone pair of
which participates in the 18p aromatic conjugation pathway
of a [17]triaza-annulene. Due to the number of inner NH
protons, type I and type II azacorroles should serve as triva-
lent and divalent ligands, respectively. In other words, differ-
ent valence states of central metal ions would alter the
structure and p conjugation of azacorroles. These potential
variations in azacorroles owing to the outer nitrogen atom
would add novel functions to corrole, thus expanding the
porphyrinoid chemistry. However, there was only one exam-
ple of synthesis of an azacorrole with b-alkyl substituents.[4]
Porphyrinoids have attracted considerable attention due to
their remarkable properties. Importantly, such properties
can be drastically altered by change of the porphyrinoid
skeleton. For instance, corrole, in which one methine carbon
of porphyrin is missing, shows quite different properties
from porphyrin, particularly in view of coordination chemis-
try.[1] Corrole skeleton can stabilize high-valent metal spe-
cies, such as FeIV, CoV, MnV, and MnVI.[2] As observed in the
corrole chemistry, creation of a novel skeleton eventually
leads to a novel properties. Various porphyrinoid skeletons
have been developed and their unique properties have been
unveiled. However, azacorrole, in which one of the meso-
carbon atoms of corrole is replaced with nitrogen, remained
almost unexplored despite its quite simple structure shown
in Scheme 1.[3] In fact, there was no precedent report on the
synthesis of meso-aryl azacorroles.
1
Unfortunately, neither H NMR spectrum nor X-ray data of
the azacorrole were described; hence, the structure and aro-
maticity of azacorrole are still in question. Moreover, there
was no precedent report on the synthesis of meso-aryl-sub-
stituted azacorroles. Herein, we report the synthesis and
properties of NiII azacorroles by Buchwald–Hartwig amina-
tion of a dipyrrin precursor.[5]
The key of the present synthetic protocol of NiII azacor-
roles is transition-metal catalysis. Recently, we have demon-
strated that a,a’-dichlorodipyrrin derivatives are good pre-
cursors for construction of porphyrinoids by combination
with metal-mediated reactions.[6] Syntheses of porphyrinoids
have largely relied on acid-promoted condensation–oxida-
tion of pyrroles with aldehydes. However, metal-mediated
reactions offer us an opportunity to access novel porphyri-
noids, which are difficult to synthesize by the conventional
porphyrin synthesis.
Scheme 1. Corrole and two possible tautomeric structures of azacorrole.
The bold lines indicate the aromatic 18p conjugation circuit.
[a] M. Horie, Y. Hayashi, Dr. S. Yamaguchi, Prof. Dr. H. Shinokubo
Department of Applied Chemistry, Graduate School of Engineering
Nagoya University
Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan)
Fax : (+81)52-789-5113
E-mail: hshino@apchem.nagoya-u.ac.jp
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201200485.
Chem. Eur. J. 2012, 18, 5919 – 5923
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5919

Results and Discussion
along with the formation of azacorrole 3 in a lower yield
(13% yield). This result indicates that the product distribu-
tion depends on the reaction conditions including the choice
of the phosphine ligands.
The synthetic protocol is shown in Scheme 2, in which a,a’-
dichlorodipyrrin NiII complex 1 was employed as a precursor.
We attempted Buchwald–Hartwig amination of 1 with ex-
pectation of the formation of diazaporphyrin NiII complex
2.[7,8] We observed the formation of two green spots by TLC
Compound 2 was easily identified to be NiII 5,15-diazapor-
1
phyrin based on its highly symmetric H NMR spectrum and
MS (ESI-TOF) analysis. The assignment was further sup-
ported by the X-ray structure analysis (Figure 1a and b). On
1
the other hand, the H NMR spectrum of 3 in CDCl3 dis-
played rather broad peaks in the aromatic region from d=
Scheme 2. Buchwald–Hartwig amination of dipyrrin NiII complex 1.
analysis. High resolution MS (ESI-TOF) analysis suggested
that the products were nickel azacorrole 3 and N-benzylaza-
corrole 4 (Scheme 2). After separation by silica-gel chroma-
tography, azacorroles 3 and 4 were isolated in 27 and 8%
yields as black solids, respectively. In addition, a trace
amount of NiII 5,15-diazaporphyrin 2 was also obtained.
As a plausible reaction mechanism for the formation of
À
nickel azacorrole 3, we propose double C N coupling of
1 with benzylamine to provide the tetrapyrrole intermediate
5, reductive homocoupling to form N-benzylazacorrole 4,
and debenzylation to azacorrole 3 (Scheme 3). A trace
Scheme 3. Proposed reaction pathway for formation of 3 from 1.
amount of the intermediary open-chain tetrapyrrole 5 was
also isolated from the reaction mixture. Presumably, the
benzyl group was cleaved in situ by the action of Pd0 species.
In fact, we confirmed debenzylation of 4 to azacorrole 3.
Thus, treatment of benzylazacorrole 4 under the same reac-
tion conditions resulted in formation of 3 in 40% yield. In-
terestingly, the use of a different catalyst combination of
Figure 1. X-ray crystal structures: a) top view and b) side view of 2;
c) top view and d) side view of 3; e) top view and f) side view of 4; g) top
view and h) side view of 6; i) top view and j) side view of 7. meso-Aryl
substituents are omitted for clarity. The thermal ellipsoids are scaled to
the 50% probability level.
[PdACHTUNGTRENNUNG(OAc)2-X-Phos] afforded diazaporphyrin 2 in 20% yield
5920
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 5919 – 5923

Synthesis of Nickel(II) Azacorroles
FULL PAPER
acetylated azacorrole 6 in 62% yield. In contrast, C-acyla-
tion occurred exclusively at the C8 position proximal to the
NH group to give b-acetylazacorrole 7 in 53% yield through
electrophilic substitution in the presence of zinc metal.[12]
Importantly, no other regioisomers were detected in the re-
action mixture. This regioselectivity to the C8 position is no-
table, because electrophilic substitution toward regular cor-
roles predominantly occurs in the C2 and C17 positions
(Schemes 4 and 5).[13] X-ray diffraction analysis of N- and C-
1
Figure 2. a) 1H NMR spectrum of 3 in CDCl3 and H NMR spectrum of 3
after the addition of hydroquinone. b) Possible structures of paramagnet-
ic species in the solution of 3.
7.5 to 8.5 ppm (Figure 2a). In addition, the ESR spectrum
of the solution of 3 exhibited a weak signal probably due to
some organic radicals (g=2.0047), but the temperature-de-
pendent magnetic susceptibility by the superconducting
quantum interference device (SQUID) magnetometer ne-
gated the existence of paramagnetic species in the solid
sample of 3 (Figure S14 the Supporting Information). On
the basis of these findings, we assigned 3 as a NiII complex
with type II structure, in which the nickel takes a low-spin
state in a square-planar geometry. The highly planar struc-
ture of azacorrole 3 was unambiguously elucidated by the
X-ray crystallographic analysis (Figure 1c and d).
Scheme 4. Site-selective functionalization of azacorrole 3 by acylation.
The presence of some radical species in solution of 3 is
probably because of adventitious oxidation of azacorrole 3
under ambient conditions. The paramagnetic species could
be a delocalized p radical or a p-radical cation of 3, because
the observed g value and broad shape of the ESR signal
match with ligand radicals rather than NiIII complex of
type I azacorrole (Figure 2c).[9] In the presence of a small
Scheme 5. Electrophilic substitution of normal corrole.[12a]
1
amount of hydroquinone as antioxidant, the H NMR spec-
acylated corroles 6 and 7 revealed their structures (Fig-
ure 1 g–j). Whereas the acetyl moiety in 6 stands perpendic-
ularly to the macrocycle, which adopts coplanar conforma-
tion in 7 due to intramolecular hydrogen-bonding interac-
tion between the meso-NH proton, which is supported by
the downfield-shifted NH peak at d=13.94 ppm. The pyrrol-
ic protons of 6 still appeared in the aromatic region around
d=8 ppm, indicating no significant loss of aromaticity by N-
acylation of NiII azacorrole. The observed dual reactivity
toward an electrophile highlights some similarity to that of
pyrrole.
The shapes of the UV/Vis absorption spectra of azacor-
role 3, N-acetylazacorrole 6, and C-acetylazacorrole 7 are
similar to those of regular corroles and exhibit Soret bands
and Q-like bands, which are attributable for aromatic por-
phyrinoids (Figure 3). A substantial redshift of the Q-like
band observed for 7 resulted from effective expansion of
conjugation due to the coplanar carbonyl group. Similar red-
shift was also observed in formyl-substitued corroles.[14]
Electrochemical properties of 3, 6, and 7 were also studied
by cyclic voltammetry in CH2Cl2 containing 0.1m Bu4NPF6
trum of 3 exhibited distinct four doublet peaks for b-pyrrolic
protons (Figure 2b). Moreover, outer NH proton appeared
in the substantially downfield at d=11.39 ppm. Therefore,
azacorrole 3 is concluded to be a distinctly aromatic
[17]triaza-annulene. The nucleus independent chemical shift
(NICS) value at the point a (indicated in Figure 1c) is calcu-
lated to be d=À17.9 ppm, suggesting strong aromatic char-
acter of 3.[10] The aromaticity of 3 clearly indicates that the
lone pair on the outer nitrogen actually participates in the
18p conjugation. Only a few examples of such large aza-an-
nulenic macrocycles with odd-numbered rings are reported
due to synthetic difficulty.[11] Furthermore, a porphyrinoid
with the amine-type nitrogen atom on the p conjugation is
also rare.
NiII azacorrole 3 has an acidic N H bond at the meso-po-
À
sition, which should be more reactive than the correspond-
À
ing C H bond of corrole. This feature can be employed as
an effective foothold for functionalization of azacorrole by
such as simple acylation. For example, treatment of 3 with
acetyl chloride in the presence of NaH as a base gave N-
Chem. Eur. J. 2012, 18, 5919 – 5923
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5921

H. Shinokubo et al.
1.78 ppm (s, 12H, mesityl); 13C NMR (CDCl3): d=150.5, 144.0, 139.0,
138.5, 135.2, 134.2, 133.6, 128.0, 120.9, 21.5, 21.4 ppm; UV/Vis (CH2Cl2):
lmax (e)=375 (63000), 391 (82000), 573 nm (61000 mÀ1 cmÀ1); HRMS
(ESI): m/z calcd for C36H30N6Ni+: 605.1943 [M+H+]; found: 605.1958.
Single crystals suitable for X-ray diffraction analysis were obtained by
slow vapor diffusion of CH3CN into a chloroform solution of 2. Crystallo-
graphic data: C36H30N6Ni; Mw =605.37 gmolÀ1; monoclinic; C2/c (No.
15); a=42.05(3), b=11.585(7), c=19.735(12) ꢁ; b=115.179(10)8; V=
8700(9) ꢁ3; Z=12; 1calcd =1.387 gcmÀ1
; T=153(2) K; R1 =0.0466 [I>
2.0s(I)], Rw =0.1439 (all data); GOF=1.024 [I>2.0s(I)].
NiII 10-azacorrole 3: 1H NMR (CDCl3): d=11.39 (s, 1H, NH), 8.30 (d,
J=4.5 Hz, 2H, b), 8.23 (d, J=4.5 Hz, 2H, b), 7.96 (d, J=4.5 Hz, 2H, b),
7.93 (d, J=4.5 Hz, 2H, b), 7.17 (s, 4H, mesityl), 2.55 (s, 6H, mesityl),
1.93 ppm (s, 12H, mesityl); 13C NMR (CDCl3): d=144.3, 140.4, 138.5,
137.4, 135.1, 132.7, 132.3, 127.7, 127.6, 124.9, 116.7, 111.4, 21.3, 20.9 ppm
(one peak was not observed probably because of overlapping); UV/Vis
(CH2Cl2): lmax (e)=391 (89000), 560 (8000), 581 (8000), 624 nm
(8000 mÀ1 cmÀ1); HRMS (ESI-TOF): m/z calcd for C36H30N5NiÀ: 590.1860
[MÀHÀ]; found: 590.1860. Single crystals suitable for X-ray diffraction
analysis were obtained by slow vapor diffusion of hexane into a 1,2-di-
chloroethane solution of 3. Crystallographic data: C36H31N5Ni; Mw =
592.37 gmolÀ1; monoclinic; P21 (No. 4); a=8.2257(18), b=13.707(3), c=
Figure 3. UV/Vis absorption spectra of azacorrole 3 (c), N-acetylaza-
corrole 6 (b), and C-acetylazacorrole 7 (a), in CH2Cl2.
(Figure S15 in the Supporting Information). The first oxida-
tion wave for azacorrole 3 was observed at relatively low
potential [0.13 V (vs. ferrocene/fecrrocenium (Fc/Fc+))] be-
cause of electron donation from the outer nitrogen atom.
The low oxidation potential of azacorrole 3 is in sharp con-
trast to that of diazaporphyrin 2 (0.81 V). Although both N-
acetyl- and C-acetylazacorroles 6 and 7 exhibited higher oxi-
dation potentials (0.24 V for 6 and 0.32 V for 7) due to the
electron-withdrawing acyl group, C-acylation was more in-
fluential. Thus, the electronic feature of azacorrole can be
effectively manipulated by regioselective functionalization
at either b-C or meso-N positions.
13.050(3); b=101.556(4)8; V=1441.5(5) ꢁ3; Z=2; 1calcd =1.365 gcmÀ1
;
T=153(2) K; R1 =0.0672 [I>2.0s(I)]; Rw =0.1830 (all data); GOF=
1.068 [I>2.0s(I)].
NiII N-benzyl-10-azacorrole 4: 1H NMR (CDCl3): d=8.25 (d, J=4.3 Hz,
2H, b), 8.14 (d, J=4.8 Hz, 2H, b), 7.96 (d, J=4.8 Hz, 2H, b), 7.87 (d, J=
4.3 Hz, 2H, b), 7.28 (m, 3H, Ph), 7.18 (m, 2H, Ph), 7.14 (s, 4H, mesityl),
6.98 (s, 2H, methylene), 2.52 (s, 6H, mesityl), 1.93 ppm (s, 12H, mesityl);
13C NMR (CDCl3): d=145.3, 144.3, 139.1, 138.5, 138.1, 135.8, 133.7,
133.6, 133.1, 129.7, 128.8, 128.7, 128.3, 126.0, 125.7, 117.6, 112.2, 57.7,
22.0, 21.6 ppm; UV/Vis (CH2Cl2): lmax (e)=395 (75000), 564 (8000), 589
(6000), 639 nm (7000 mÀ1 cmÀ1); HRMS (ESI): m/z calcd for C43H37N5NiÀ:
716.2100 [M+ClÀ]; found: 716.2096. Single crystals suitable for X-ray
diffraction analysis were obtained by slow vapor diffusion of EtOH into
a
1,2-dichloroethane
solution
of
;
4.
Crystallographic
data:
C88H78Cl2N10Ni2; Mw =1463.92 gmolÀ1
monoclinic; P21 (No. 4); a=
Conclusion
11.5914(10), b=24.867(2), c=13.6500(11) ꢁ; b=112.4730(10)8; V=
3635.8(5) ꢁ3; Z=2; 1calcd =1.337 gcmÀ1; T=153(2) K; R1 =0.0491 [I>
2.0s(I)]; Rw =0.1274 (all data); GOF=1.042 [I>2.0s(I)].
We have achieved the first synthesis of meso-aryl azacorrole
NiII complexes by Buchwald–Hartwig amination of
a bis(a,a’-dichlorodipyrrinato) Ni complex 1. Azacorrole
NiII complex 3 can be recognized as a [17]triaza-annulene
with distinct aromaticity. We have also accomplished regio-
selective functionalization of NiII azacorrole both at the
meso-nitrogen and b-carbon atoms. Further investigation on
the synthesis of free-base azacorrole and metal-coordination
behavior is currently ongoing in our laboratory.
Procedure for N-acylation: Sodium hydride (8.0 mg, 0.20 mmol) was
washed with dry hexane (3ꢂ3 mL) before adding dry THF (2 mL) under
nitrogen atmosphere. A solution of 3 (14.8 mg, 25 mmol) in THF (5 mL)
was added dropwise at 08C. The reaction mixture was stirred for 30 min,
and acetyl chloride (15.0 mL, 0.21 mmol) was added dropwise. The reac-
tion mixture was stirred at RT for 5 h. The mixture was poured into
water and extracted with AcOEt. The organic layer was dried with
Na2SO4 and evaporated in vacuo. The crude product was purified by
silica-gel column chromatography (CHCl3/hexane as an eluent) to give 6
in 62% yield (9.8 mg, 16 mmol) as a black solid.
N-Acetylazacorrole 6: 1H NMR (CDCl3): d=8.20 (d, J=4.3 Hz, 2H, b),
8.15 (d, J=4.8 Hz, 2H, b), 7.85 (d, J=4.2 Hz, 2H, b), 7.79 (d, J=4.5 Hz,
2H, b), 7.15 (s, 4H, mesityl), 3.28 (s, 3H, -C(O)CH3), 2.53 (s, 6H, mesi-
tyl), 1.93 ppm (s, 12H, mesityl); 13C NMR (CDCl3): d=176.21, 145.4,
138.4, 138.3, 137.6, 134.8, 133.1, 132.9, 132.4, 129.7, 127.7, 127.6, 125.8,
117.3, 110.8, 21.3, 20.8 ppm; UV/Vis (CH2Cl2): lmax (e)=394 (88000), 563
(8000), 596 (5000), and 645 nm (7000 mÀ1 cmÀ1); HRMS (ESI-MS): m/z
calcd for C38H33N5NiOÀ: 633.2006 [MÀ]; found: 633.2033. Single crystals
suitable for X-ray analysis were obtained by slow vapor diffusion of
hexane into a dichloromethane solution of 6. Crystallographic data:
Experimental Section
Synthesis of 3 by Buchwald–Hartwig amination of 1: A Schlenk tube
equipped with a septum rubber containing 1 (143 mg, 0.200 mmol), [Pd2-
ACHTUNGTRENNUNG(dba)3·CHCl3] (dba=dibenzylideneacetone; 10.4 mg, 10.0 mmol),
[tBu3P·HBF4] (11.6 mg, 40.0 mmol), and KOtBu (112.2 mg, 1.00 mmol)
was evacuated and then refilled with N2. Dry toluene (5 mL) and benzyl-
amine (50.0 mL, 0.460 mmol) were added by syringes. The reaction mix-
ture was stirred at 1008C for 20 h. The resulting mixture was filtered
through a pad of Celite (CH2Cl2 as an eluent) and the solvent was evapo-
rated in vacuo. The crude product was purified by silica-gel column chro-
matography (CH2Cl2/hexane as an eluent) to give 3 (32.0 mg, 54.1 mmol)
and 4 (10.3 mg, 15.1 mmol) in 27 and 8% yields, respectively, along with
a trace amount of 2.
C38H33N5NiO; Mw =634.40 gmolÀ1
;
monoclinic; C2 (No. 5); a=
26.602(11), b=11.237(5), c=11.071(4) ꢁ; b=90.687(8)8; V=3309(2) ꢁ3;
Z=4; 1calcd =1.273 gcmÀ1; T=153(2) K; R1 =0.0627 [I>2.0s(I)]; Rw =
0.1539 (all data); GOF=1.095 [I>2.0s(I)].
Procedure for C-acylation: A mixture of 3 (14.8 mg, 25 mmol) and zinc
powder (5.0 mg, 76.5 mmol) was evacuated and then refilled with N2. Dry
toluene (3 mL) was added by syringe and the reaction mixture was
stirred at 1108C for 10 min. Then, acetyl chloride (3.0 mL, 42.2 mmol) was
1
NiII 5,15-diazaporphyrin 2: H NMR (CDCl3): d=9.13 (d, J=4.8 Hz, 4H,
b), 8.77 (d, J=5.1 Hz, 4H, b), 7.28 (s, 4H, mesityl), 2.59 (s, 6H, mesityl),
5922
www.chemeurj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 5919 – 5923

Synthesis of Nickel(II) Azacorroles
FULL PAPER
added by syringe and the mixture was stirred for 16 h. The resulting mix-
ture was quenched with saturated sodium dicarbonate solution and ex-
tracted with AcOEt. The organic layer was dried with Na2SO4 and evapo-
rated in vacuo. The residue was purified by silica-gel column chromatog-
raphy (CHCl3/hexane as an eluent). Recrystallization from CHCl3/MeOH
afforded 7 in 53% yield (8.4 mg, 13.3 mmol) as a green solid.
Chem. Soc. 2001, 123, 9447; b) S. Fukuzumi, H. Kotani, K. A.
Prokop, D. P. Goldberg, J. Am. Chem. Soc. 2011, 133, 1859; c) A. J.
McGown, W. D. Kerper, H. Fujii, D. P. Goldberg, J. Am. Chem. Soc.
2009, 131, 8040; d) B. Ramdhanie, J. Telser, A. Caneschi, L. N. Za-
kharov, A. L. Rheingold, D. P. Goldberg, J. Am. Chem. Soc. 2004,
126, 2515.
C-Acetylazacorrole 7: 1H NMR (CDCl3): d=13.94 (s, 1H, NH), 8.31 (s,
1H, b), 8.16 (m, 3H, b), 7.94 (d, J=4.5 Hz, 1H, b), 7.84 (d, J=4.5 Hz,
1H, b), 7.74 (d, J=4.5 Hz, 1H, b), 7.18 (s, 2H, mesityl), 7.14 (s, 2H, me-
[4] W. Johnson, I. T. Kay, R. Rodrigo, J. Chem. Soc. 1963, 2336. meso-
Arylazacorrole has not been synthesized.
[5] a) J. P. Wolfe, S. Wagaw, J.-F. Marcoux, S. L. Buchwald, Acc. Chem.
Res. 1998, 31, 805; b) J. F. Hartwig, Angew. Chem. 1998, 110, 2154;
Angew. Chem. Int. Ed. 1998, 37, 2046; c) J. F. Hartwig, Acc. Chem.
Res. 2008, 41, 1534; d) D. S. Surry, S. L. Buchwald, Angew. Chem.
2008, 120, 6438; Angew. Chem. Int. Ed. 2008, 47, 6338.
À
sityl), 2.83 (s, 3H, C(O)CH3), 2.55 (s, 3H, mesityl), 2.52 (s, 3H, mesityl),
1.95 (s, 6H, mesityl), 1.94 ppm (s, 6H, Me); 13C NMR (CDCl3): d=197.1,
148.8, 143.2, 142.8, 139.9, 138.4, 138.2, 137.9, 137.7, 134.7, 134.5, 134.4,
134.2, 134.0, 133.9, 130.5, 128.4, 127.8, 127.7, 123.9, 119.6, 119.0, 117.1,
114.2, 27.6, 21.4, 21.3, 20.9 ppm (two peaks were not observed probably
because of overlapping); UV/Vis (CH2Cl2): lmax (e)=410 (64000), 515
(8000), 559 (4000), 663 nm (11000 mÀ1 cmÀ1); HRMS (ESI): m/z calcd for
C38H33N5NiOÀ: 632.1975 [MÀHÀ]; found: 632.1966. Single crystals suita-
ble for X-ray diffraction analysis were obtained by slow vapor diffusion
[6] T. Sakida, S. Yamaguchi, H. Shinokubo, Angew. Chem. 2011, 123,
2328; Angew. Chem. Int. Ed. 2011, 50, 2280.
[7] For diazaporphyirins, see: a) N. Kobayashi in The Porphyrin Hand-
book, Vol. 2 (Eds.: K. M. Kadish, K. M. Smith, R. Guilard), Aca-
demic Press, San Diego, 2000, p.301; b) J. P. Singh, L. Y. Xie, D. Dol-
phin, Tetrahedron Lett. 1995, 36, 1567; c) S. Neya, H. Hori, K. Imai,
Y. Kawamura-Konishi, H. Suzuki, Y. Shiro, T. Iizuka, N. Funasaki, J.
Biochem. 1997, 121, 654; d) H. Shinmori, F. Kodaira, S. Matsugo, S.
Kawabata, A. Osuka, Chem. Lett. 2005, 34, 322; e) O. G. Khelevina,
N. V. Chizhova, P. A. Stuzhin, A. S. Semeikin, B. D. Berczin, Russ. J.
Coord. Chem. 1996, 22, 811; f) G. Khelevina, N. V. Chizhova, P. A.
Stuzhin, A. S. Semeikin, B. D. Berczin, Russ. J. Phys. Chem. 1997,
71, 74.
of MeOH into
C38H33N5NiO; Mw =634.40 gmolÀ1
8.6358(18), b=45.858(10), c=8.3877(18);
3113.9(11) ꢁ3; Z=4; 1calcd =1.353 gcmÀ1
T=93(2) K; R1 =0.0982 [I>
a
toluene solution of 7. Crystallographic data:
monoclinic; Cc (No. 9); a=
b=110.372(4)8; V=
;
;
2.0s(I)]; Rw =0.2215 (all data); GOF=1.281 [I>2.0s(I)].
CCDC-861381 (2), CCDC-861382 (3), CCDC-861383 (4), CCDC-861384
(6), and CCDC-861385 (7) contain 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.
[8] Matano et al. have independently developed an efficient synthetic
procedure for the synthesis of 5,10-diazaporphyrin from dipyrrin
metal complexes. Y. Matano, T. Shibano, H. Nakano, H. Imahori,
Chem. Eur. J. 2012, 18, DOI:10.1002/chem.201200463.
[9] For a paramagnetic Ni corrole, see: S. Will, J. Lex, E. Vogel, H.
Schmickler, J. P. Gisselbrecht, C. Haubtmann, M. Bernard, M.
Gross, Angew. Chem. 1997, 109, 367; Angew. Chem. Int. Ed. Engl.
1997, 36, 357.
Acknowledgements
This work was supported by Grants-in-Aid for Scientific Research (No.
23108705 “p Space”) from MEXT, Japan and the Global COE Program
in Chemistry of Nagoya University. We thank Prof. Yoshihiro Matano
(Kyoto University) for fruitful discussions. We are indebted to Prof.
Kunio Awaga and Prof. Hirofumi Yoshikawa (Nagoya University) for
help with ESR and SQUID measurements. H.S. also acknowledges Toray
Science for financial support. S.Y. appreciates the JSPS Research Fellow-
ship for Young Scientists.
[10] The NICS value has been successfully used as a measure of aroma-
ticity, see: a) Z. Chen, C. S. Wannere, C. Corminboeuf, P. Puchta, P.
von R. Schleyer, Chem. Rev. 2005, 105, 3842; b) P. von R. Schleyer,
C. Maerker, A. Dransfeld, H. J. Jiao, N. J. R. v. E. Hommes, J. Am.
Chem. Soc. 1996, 118, 6317.
[11] For annulenes with odd numbered rings, see: a) S. Hayashi, E. Tsur-
umaki, Y. Inokuma, P. Kim, Y. M. Sung, D. Kim, A. Osuka, J. Am.
Chem. Soc. 2011, 133, 4254; b) Y.-H. Lai, P. Chen, J. Org. Chem.
1997, 62, 6060; c) R. H. Mitchell, V. S. Iyer, J. Am. Chem. Soc. 1996,
118, 722; d) R. H. Mitchell, R. Zhou, Tetrahedron Lett. 1991, 32,
6319; e) T. D. Lash, A. D. Lammer, G. M. Ferrence, Angew. Chem.
Int. Ed. 2011, 50, 9718; f) K. Fujino, Y. Hirata, Y. Kawabe, T. Mori-
moto, A. Srinivasan, M. Toganoh, Y. Miseki, A. Kudo, H. Furuta,
Angew. Chem. 2011, 123, 6987; Angew. Chem. Int. Ed. 2011, 50,
6855.
[1] For excellent reviews on corrole chemistry, see: a) D. T. Gryko, Eur.
J. Org. Chem. 2002, 1735; b) Z. Gross, H. B. Gray, Adv. Synth. Catal.
2004, 346, 165; c) A. Ghosh, E. Steene, J. Inorg. Biochem. 2002, 91,
423; d) I. Aviv-Harel, Z. Gross, Chem. Eur. J. 2009, 15, 8382;
e) D. T. Gryko, J. Porphyrins Phthalocyanines 2008, 12, 906; f) R.
Paolesse, Synlett 2008, 2215; g) D. T. Gryko, J. P. Fox, D. P. Gold-
berg, J. Porphyrins Phthalocyanines 2004, 8, 1091; h) I. Aviv-Harel,
Z. Gross, Coord. Chem. Rev. 2011, 255, 717.
[12] For acylation of pyrrole with zinc powder, see: J. S. Yadav, B. V. S.
Reddy, G. Kondaji, R. Srinivasa Rao, S. Praveen Kumar, Tetrahe-
dron Lett. 2002, 43, 8133.
[13] a) A. Mahammed, I. Goldberg, Z. Gross, Org. Lett. 2001, 3, 3443;
b) Z. Gross, A. Mahammed, J. Porphyrins Phthalocyanines 2002, 6,
553.
[14] a) I. Saltsman, A. Mahammed, I. Goldberg, E. Tkachenko, M. Bo-
toshansky, Z. Gross, J. Am. Chem. Soc. 2002, 124, 7411; b) J. J.
Weaver, K. Sorasaenee, M. Sheikh, R. Goldschmidt, E. Tkachenko,
Z. Gross, H. B. Gray, J. Porphyrins Phthalocyanines 2004, 8, 76;
c) K. Sorasaenee, P. Taqavi, L. M. Henling, E. Tkachenko, H. B.
Gray, A. Mahammed, Z. Gross, J. Porphyrins Phthalocyanines 2007,
11, 189.
[2] a) S. Will, J. Lex, E. Vogel, V. A. Adamian, E. Van Caemelbecke,
K. M. Kadish, Inorg. Chem. 1996, 35, 5577; b) E. Vogel, S. Will,
A. S. Tilling, L. Neumann, J. Lex, E. Bill, A. X. Trautwein, K. Wie-
ghardt, Angew. Chem. 1994, 106, 771; Angew. Chem. Int. Ed. Engl.
1994, 33, 731; c) A. Kumar, I. Goldberg, M. Botoshansky, Y. Buch-
man, Z. Gross, J. Am. Chem. Soc. 2010, 132, 15233; d) Z. Gross, G.
Golubkov, L. Simkhovich, Angew. Chem. 2000, 112, 4211; Angew.
Chem. Int. Ed. 2000, 39, 4045.
[3] Corroles in which all meso-carbons are replaced with nitrogen
atoms are known as corrolazines, synthesis of which was achieved in
2001, and the intriguing reactivity based on central metals has been
revealed, see: a) B. Ramdhanie, C. L. Stern, D. P. Goldberg, J. Am.
Received: February 14, 2012
Published online: March 27, 2012
Chem. Eur. J. 2012, 18, 5919 – 5923
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5923