C-fused norrole: A fused corrole isomer bearing a N,C-linked bipyrrole unit

Article abstract of DOI:10.1021/jo2014017

Oxidative cyclization of a doubly N-confused bilane afforded a N-confused N,C-linked corrole (N-confused norrole), which was readily oxidized to form a C-fused N,C-linked corrole (C-fused norrole).

Full text of DOI:10.1021/jo2014017

NOTE
pubs.acs.org/joc
C-Fused Norrole: A Fused Corrole Isomer Bearing a N,C-Linked
Bipyrrole Unit
Motoki Toganoh, Yasunori Kawabe, and Hiroyuki Furuta*
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka
819-0395, Japan
S Supporting Information
b
ABSTRACT: Oxidative cyclization of a doubly N-confused
bilane afforded a N-confused N,C-linked corrole (N-confused
norrole), which was readily oxidized to form a C-fused N,C-
linked corrole (C-fused norrole).
orrole is a tetrapyrrolic macrocycle containing a direct C,C-
C
linkage between two neighboring pyrrole rings.1 Corrole has
an ability to stabilize transition metal centers of high oxidation
states due to its trianionic character and a narrow space of the
macrocyclic core.2 Recent studies revealed that corrole deriva-
tives would be promising candidates as catalysts and biologically
active substances.3 Thus, studies on corrole and related com-
pounds have become one of the most active research fields in the
porphyrinoid chemistry.4
Figure 1. Structures of the corrole isomers.
undesired product ratio was not improved by decreasing the
amount of TFA (entry 2). Meanwhile, usage of BF3•OEt2
resulted in considerable refinement of product selectivity to give
2 in 27% yield together with 3 in 13% yield (entry 3). Further
improvement was attained by adding CH2Cl2 as solvent, and the
yield of 2 reached up to 46% (entries 4À6). While we suspect an
acid-catalyzed conversion from 2 to 3, such isomerization was
not yet observed by treatment of 2 with acids.
Second, doubly N-confused bilanes (linear tetrapyrroles) were
synthesized (Scheme 1). Deprotection of 2 with Bu4N+FÀ
proceeded quantitatively to give 4. Then, acylation reaction of
4 was achieved with a thioester method10 to give acylated
products 5 and 6 in 42 and 15% yields, respectively. The attempts
of acylation with pentafluorobenzoyl chloride resulted in the
lower yields. Reduction of 5 with excess NaBH4 and subsequent
TFA-catalyzed condensation reaction with dipyrromethane gave
doubly N-confused bilane 8 in 44% yield (two steps). Similarly,
reduction of 6 and subsequent condensation reaction with
pyrrole gave 10, an isomer of 8, in 84% yield.
Recently, we have reported a series of corrole (COR) isomers,
namely, N-confused corrole (NCC) and N,C-linked corrole or
norrole (NOR).5 The latter was the first example of oligopyrrolic
macrocycles possessing a N,C-linked bipyrrole moiety in their
skeletons. The finding of this unusual N,C-linkage inspired us to
explore a scope of N,C-linked oligopyrrolic macrocycles. Con-
sequently, we have designed a new member of the corrole family,
N-confused norrole (NCN, Figure 1), which is also a member of
multiply N-confused tetrapyrrolic macrocycles.6
For the stepwise synthesis of a series of multiply N-confused
porphyrinoids, it is necessary to handle the multiply N-confused
oligopyrroles as precursors or key building blocks, freely. How-
ever, in spite of recent development in the synthesis of N-con-
fused porphyrinoids,7 poor examples have been reported for the
syntheses of such oligopyrroles.8 Hence, a rapid and convenient
method for the synthesis of multiply N-confused oligopyrroles
was investigated in advance.
First, preparation of doubly N-confused dipyrromethane (2)
was examined by acid-catalyzed condensation reactions of 1-
(triisopropylsilyl)pyrrole (TIPS-pyrrole, 1) as shown in Table 1.
The TIPS group effectively disturbs the reaction at R-pyrrolic
positions due to steric hindrance.9 Upon treatment of 1 (10
equiv) and C6F5CHO (1 equiv) with trifluoroacetic acid (TFA,
0.5 equiv), the desired product (2) was obtained in 19% yield
(entry 1). Disappointingly, singly N-confused dipyrromethane
(3) was also obtained as a major product in 29% yield. This
Finally, oxidative intramolecular cyclization reactions of dou-
bly N-confused bilanes were investigated. When 8 was treated
with a variety of oxidants, such as 2,3-dichloro-5,6-dicyano-1,4-
benzoquinone (DDQ), p-chloranil, o-chloranil, or FeCl3,
Received: July 8, 2011
Published: August 02, 2011
r
2011 American Chemical Society
7618
dx.doi.org/10.1021/jo2014017 J. Org. Chem. 2011, 76, 7618–7622
|

The Journal of Organic Chemistry
NOTE
Table 1. Acid-Catalyzed Condensation Reactions of TIPS-Pyrrole and Pentafluorobenzaldehyde
entry
X
Y
solvent
acid
conditions
yield of 2 (%)
yield of 3 (%)
1
2
3
4
5
6
10
1
1
1
1
1
1
none
TFA (0.5 equiv)
23 °C, 3 h
19
13
27
42
24
46
29
18
13
23
19
6
5
none
TFA (0.02 equiv)
23 °C, 33 h
0 °C, 105 min
0 °C, 30 min
0 °C, 10 min
0 °C, 5 min
5
none
BF3•OEt2 (0.1 equiv)
BF3•OEt2 (0.4 equiv)
BF3•OEt2 (0.4 equiv)
BF3•OEt2 (2 equiv)
5
CH2Cl2
CH2Cl2
CH2Cl2
2.5
5
Scheme 1. Preparation of Doubly N-Confused Bilanes
Figure 2. X-ray structures of 12: (a) top view, (b) side view. The
thermal ellipsoids are shown at the 30% probability level. The meso-aryl
groups are omitted in (b) for clarity.
variety of oxidants. However, no cyclic compound such as 14 was
obtained, contrary to our expectation.
The structure of 12 was unambiguously determined by the
X-ray crystallographic analysis. The ORTEP drawings of 12 are
shown in Figure 2. Formation of the CÀC bond inside the corrole
macrocycle was evidently confirmed. Existence of the peripheral
NH proton in the solid state was supported by formation of
hydrogen bonding with CH3CN in the crystal, where the NÀN
distance is 3.003 Å (Figure S9 in Supporting Information). Beside
this, 12 showed an anion binding affinity for halide in CH2Cl2
solution (Ka = 80 MÀ1 for ClÀ), indicating the existence of a
peripheralNH moiety even in solution. The CÀC and CÀN bond
lengths newly formed by the oxidation reaction are 1.490(10) and
1.395(8) Å, respectively. Because of the narrow space inside the
macrocycle, the dipyrromethene unit was distorted and deviated
from planarity (Figure 2b).
Absorption spectrum of 12 in CH2Cl2 is shown in Figure 3.
The split Soret-like bands were observed at 404 and 430 nm, and
the Q-type band was observed at 606 nm. The theoretical
oscillator strengths calculated with a time-dependent density
functional theory (TDDFT) method are in good agreement with
the experimental result.12 In fluorescence measurement, very
dehydrogenation reaction proceeded and analyses of the reaction
mixtures by matrix-assisted laser desorption ionization mass
spectra afforded an intense molecular ion peak of m/z = 796,
which corresponds exactly to N-confused norrole (11) or doubly
N-confused corrole (13). However, unfortunately, the corre-
sponding product was readily oxidized or decomposed during
purification, and isolation of 11 or 13 was so far unsuccessful.
Since a weak peak of m/z = 794 was detected in many cases, more
harsh conditions were applied. Thus, the reaction of 8 with DDQ
in CH3CN under reflux was achieved, and mass analysis of the
crude product gave a strong molecular ion peak of m/z = 794.
After silica gel column separation, C-fused norrole (12) was
isolated in 2% yield as an air-stable solid. An intramolecular C,C-
coupling reaction could be facilitated by the narrow space inside
the macrocycle of 11 as well as high flexibility of the N-linked and
N-confused pyrrole rings.11 The reason for the low yield was
partly explained by the competitive intermolecular oxidative
coupling reactions leading to octapyrrolic and higher oligopyr-
rolic compounds, as judged by the mass analyses. Separately,
oxidative cyclization reaction of 10 was also attempted with a
7619
dx.doi.org/10.1021/jo2014017 |J. Org. Chem. 2011, 76, 7618–7622

The Journal of Organic Chemistry
NOTE
Table 2. NICS Values, HOMA Indices, and HOMOÀLUMO
Gap Energies of the Corrole Family
structure
NICS (ppm)
HOMAall
HOMA18
ΔEHL (eV)
12
CORa
NCCa
NORa
À10.92
À12.14
À6.82
À7.28
À2.91
0.471
0.726
0.646
0.669
0.571
0.537
0.789
0.645
0.711
0.632
2.29
2.53
1.85
2.23
2.00
NCN
a From ref 5.
Scheme 2. Oxidative Cyclization Reaction of 8
Figure 3. Absorption spectrum of 12 in CH2Cl2. Normalized theore-
tical oscillator strengths and solution color are also shown.
weak emission was observed at 679 nm in CH2Cl2 (Figure S10 in
Supporting Information, Φ < 0.001). The fairly large Stokes shift
(1774 cmÀ1) in 12 despite its rigid planar structure is uncommon
among porphyrinoids, which can be rationalized by an intramo-
lecular charge transfer process or structural transformation at the
excited state. Because the solvent effect on UVÀvis absorption of
12 is negligible (Figure S11 in Supporting Information), the
intramolecular charge transfer process should be less important
in its decay process. Thus, the large Stokes shift of 12 might be
due to structural transformation at the excited state. Considering
the rigid molecular skeleton of 12, one of the plausible structural
transformations at the excited state would be intramolecular
proton transfer, which was also proposed for the rigid porphyri-
noids like N-fused porphyrins.13 Although no direct evidence
oscillator model of aromaticity (HOMA)15 indices is also evalu-
ated for the whole skeletons (HOMAall) and [18]annulenic
circuits (HOMA18). The [18]annulenic circuits adopted are
described by the colored bold lines in Figure 1 and Scheme 2.
The black bold lines mean an absence of complete [18]annulenic
circuits. Nevertheless, they were used for calculation of
HOMA18. The HOMAall index of 12 (0.471) is significantly
smaller than those of COR (0.726), NCC (0.646), and NOR
(0.669) in spite of its largely negative NICS value. It is even
smaller than that of NCN (0.571). It could be rationalized by
severe ring strain caused by the CÀC fusion. Additionally, no
significant differences are observed between HOMAall and
HOMA18. Hence, it would be difficult to explain the aromaticity
of highly modified corrole analogues by analogy of simple
[18]annulenic macrocycles or classical Kekulꢀe description.
In conclusion, the method for the synthesis of doubly N-con-
fused oligopyrroles was developed, and their oxidation reactions
were examined. C-fused norrole (12) was isolated, and its
1
was obtained yet, the H NMR spectrum supported an excited
state intramolecular proton transfer process in 12. The NH signal
inside the macrocycle was observed at δ 10.04 ppm in CDCl3.
The large low-field shift in spite of its aromatic character (vide
infra) suggests the existence of strong intramolecular hydrogen
bonding inside the macrocycle in the ground state, which would
be an important factor for rapid intramolecular proton transfer.
Aromaticity of 12 is evaluated experimentally as well as
theoretically.12 Theoretical study on a series of corrole isomers
is achieved at the B3LYP/6-311++G**//B3LYP/6-31G** level
on the meso-pentafluorophenyl derivatives in all cases. The mean
difference in the bond lengths of main framework between the
X-ray structure and the optimized structure of 12 is 0.013 Å,
which supports reliability of the calculation method used. The
1H NMR signals (in CDCl3) of the pyrrolic CH moieties appear
in the region from δ 7.1 to 8.4 ppm, which illustrates the
existence of significant aromatic ring current. The nucleus
independent chemical shift (NICS)14 value for the optimized
structure of 12 is À10.92 ppm (Table 2), indicating moderate or
strong aromaticity of 12. This value is smaller than that of COR
(À12.14) but larger than that of NCC (À6.82) and NOR
(À7.28). The HOMOÀLUMO band gap energies (ΔEHL) show
a good correlation with the NICS values in these four com-
pounds. In the case of NCN, the presumable precursor of 12, the
NICS value indicates nearly non-aromatic character (À2.91),
possibly due to severe distortion from planarity imposed by four
hydrogen atoms inside the macrocycle. Thus, the intramolecular
CÀC bond formation from NCN to 12 would be beneficial for
aromatic stabilization through planarization. The harmonic
1
considerable aromaticity was confirmed by the H NMR mea-
surements, which is a peculiar example of C-fused oligopyrrolic
macrocycles. As the fusion reactions inside the macrocycles often
afford the molecules of unique electronic structures, further
development of this strategy is expected.16 In addition, develop-
ment on the porphyrinoids chemistry derived from the doubly
N-confused oligopyrrole units is also expected.
’ EXPERIMENTAL SECTION
General. All of the reactions were performed in oven-dried reaction
vessels under Ar or N2. Commercially available solvents and reagents
were used without further purification unless otherwise mentioned.
CH2Cl2 was distilled over CaH2. Dry THF (stabilizer free) was used as
received. Thin-layer chromatography (TLC) was carried out on alumi-
num sheets coated with silica gel 60 F254. Preparative separation was
7620
dx.doi.org/10.1021/jo2014017 |J. Org. Chem. 2011, 76, 7618–7622

The Journal of Organic Chemistry
NOTE
performed by silica gel flash column chromatography (spherical, neutral,
40À50 μm) or silica gel gravity column chromatography (spherical,
neutral, 63À210 μm). 1H NMR spectra were recorded in CDCl3
solution on a FT-NMR spectrometer at 300 MHz, and chemical shifts
were reported relative to a residual proton of a deutrated solvent, CHCl3
(δ = 7.26) in parts per million. 13C NMR spectra were recorded in
CDCl3 solution on the same instrument at 75 MHz, and chemical shifts
were reported relative to CDCl3 (δ = 77.0) in parts per million. UV/vis
absorption spectra were recorded on a UV spectrometer with a photo-
multiplier tube detector (190À750 nm) and a PbS detector
(750À3200 nm). Emission spectra were recorded on a FL spectrometer
with a photomultiplier tube detector (∼850 nm). Mass spectra were
recorded on a MALDIÀTOF MS spectrometer. High-resolution mass
spectra were measured with an ESI MS spectrometer.
(1.40 mL) under Ar. The mixture was stirred at ambient temperature for 10
min and then cooled to À78 °C. A solution of (S)-2-pyridyl pentafluoro-
benzothioate (448 mg, 1.47 mmol, 1.1 equiv) in THF (1.4 mL) was then
added dropwise over 10 min. The solution was maintained at À78 °C for 7
min. The mixture was allowed to warm to room temperature. After 2.5 h, the
reaction was quenched with saturated aqueous NH4Cl. The reaction mixture
partitioned between CH2Cl2 and water. Then, the CH2Cl2 phase was
washed with water, dried over sodium sulfate, and evaporated in vacuo. The
residue was separated by silica gel column chromatography, using hexane/
CH2Cl2 = 1/4 (v/v) as eluent. The first fraction gave 4 as a clear oil (99.0
mg, 0.317 mmol, 24%). The second fraction gave 5 as a white solid (281 mg,
0.555 mmol, 42%). The third fraction gave 6 as a white solid (144 mg, 0.206
mmol, 15%). 5: 1H NMR (CDCl3, 300 MHz, ppm) δ5.63 (s, 1H), 6.12 (br
s, 1H), 6.57 (br s, 1H), 6.62 (br s, 1H), 6.76À6.77 (m, 1H), 7.10 (br s, 1H),
8.14 (br s, 1H), 9.47 (br s, 1H); 13C NMR (CDCl3, 75 MHz, ppm) δ 30.9,
107.8, 115.7, 118.1, 119.9, 122.1, 126.8, 127.8, 130.9, 172.2 (the signals due
to the pentafluorophenyl moiety could not be assigned due to complicated
5-Pentafluorophenyl-1,9-bis(triisopropylsilyl)-1,9-diaza-
10,11-dicarbadipyrromethane (2) and 5-Pentafluorophe-
nyl-1,11-bis(triisopropylsilyl)-1-aza-10-carbadipyrromethane
(3). TIPS-pyrrole (1, 15.0 g, 67.1 mmol, 5.0 equiv) and pentafluoroben-
zaldehyde (1.66 mL, 13.4 mmol, 1.0 equiv) in 9 mL of dry CH2Cl2 were
stirred at 0 °C under Ar for 10 min. Then, BF3•Et2O (3.36 mL, 26.8 mmol,
2 equiv) was added at 0 °C and stirred further for 5 min. The resulting
reaction mixture was passed through a pad of alumina with CH2Cl2 as
eluent and evaporated in vacuo. The residue was purified by silica gel
column chromatography with hexane as eluent. The first fraction (Rf =
0.60; eluent, hexane) afforded recovered TIPS-pyrrole as a clear oil. The
second fraction afforded 3 as a clear oil (523 mg, 0.873 mmol, 6.2%). The
third fraction gave 2 as a clear white solid (3.85 g, 6.15 mmol, 45.8%). 2: 1H
NMR (CDCl3, 300 MHz, ppm) δ 1.06 (d, J = 7.5 Hz, 36H), 1.38 (sept, J =
7.5 Hz, 6H), 5.67 (s, 1H), 6.12 (br s, 2H), 6.57 (br s, 2H), 6.69 (br t, 2H);
13C NMR (CDCl3, 75 MHz, ppm) δ 11.6, 17.7, 31.9, 110.5, 120.3*, 122.5,
19
multiple coupling of 13CÀ F); HRMS (ESIÀ) foundm/z 505.04025, calcd
À
2
for C22H7F10N2O ([M À H] ) m/z 505.03987; Rf = 0.30 (CH Cl2). 6:
1H NMR (CDCl3, 300 MHz, ppm) δ 5.61 (s, 2H), 6.54 (br s, 2H), 7.05 (br
s, 2H), 9.59 (br s, 2H); 13C NMR (CDCl3, 75 MHz, ppm) δ 31.0, 120.4,
126.6, 127.1, 131.6, 173.0 (the signals due to the pentafluorophenyl moiety
could not be assigned because of the complicated multiple coupling of
13CÀ F); HRMS (ESIÀ) found m/z 699.01690, calcd for C29H6F15N2O2
19
([M À H]À) m/z 699.01898; Rf = 0.15 (CH2Cl2).
5,10,15-Tris(pentafluorophenyl)-1,8-diaza-21,22-dicarb-
abilane (8). NaBH4 (1.69 g, 44.8 mmol, 25 equiv) was added to a
stirred solution of 5 (905 mg, 1.79 mmol, 1 equiv) in THF (100 mL) and
MeOH (20 mL) at room temperature under N2. After 1.5 h, the reaction
was quenched with water and diluted with CH2Cl2. Then, the organic
phase was washed with water, dried over Na2SO4, and evaporated in
vacuo. The resulting product (7) was used in the next step without
further purification. TFA (55.0 μL, 0.716 mmol, 0.5 equiv) was added to
a solution of 7 and 5-pentafluorophenyldipyrromethane (2.80 g, 8.95
mmol, 5 equiv) in CH2Cl2 (20 mL) at room temperature under N2.
After stirring for 1 h, the reaction was quenched with water. The organic
phase was washed with water, dried over Na2SO4, and evaporated in
vacuo. The residue was purified by silica gel column chromatography
using hexane/CH2Cl2 = 1/1 (v/v) as eluent. The first fraction (Rf = 0.30,
hexane/CH2Cl2 = 2/3 (v/v)) afforded 5-pentafluorophenyldipyrro-
methane. The second fraction afforded 8 as a brown solid (957 mg,
1.19 mmol, 66.6%): 1H NMR (CDCl3, 300 MHz, ppm) δ 5.63 (s, 1H),
5.79 (br s, 1H), 5.86 (br s, 1H), 5.94 (br s, 3H), 6.02 (br s, 1H),
6.16À6.18 (m, 2H), 6.58 (br s, 1H), 6.62 (br s, 1H), 6.73 (br s, 1H), 6.74
(br s, 1H), 7.97 (br s, 1H), 8.07 (br s, 2H), 8.15 (br s, 1H); 13C NMR
(CDCl3, 75 MHz, ppm) δ 31.7, 33.08, 33.12, 33.15, 107.6, 107.77,
107.84, 107.87, 108.3, 108.6, 116.2, 116.4, 116.5, 118.0, 118.1, 123.6,
123.7, 124.6, 127.7, 127.9, 128.55, 128.63 (the signals due to the
pentafluorophenyl moieties could not be assigned because of the com-
1
124.0, 126.2, 137.5* (d, JCF = 249.1 Hz), 139.4* (d, 1JCF = 244.1 Hz),
1
145.0* (d, JCF = 246.6 Hz) (*these signals show a further multiplet
19
coupling due to the remote 13CÀ F coupling). Anal. Calcd for
C33H50F5N2Si2: C, 63.42; H, 7.90; N, 4.48. Found: C, 63.27; H, 7.85;
1
N, 4.46; Rf = 0.30 (hexane). 3: H NMR (CDCl3, 300 MHz, ppm) δ
1.01À1.07 (m, 36H), 1.27À1.50(m, 6H), 5.71 (s, 1H),5.98 (br, 1H), 6.22
(t, J = 3.0 Hz, 1H), 6.30 (br s, 1H), 6.33 (br s, 1H), 6.62 (t, J = 3.0 Hz, 1H),
6.79 (br s, 1H); 13C NMR (CDCl3, 75 MHz, ppm) δ 11.6, 13.6, 17.7, 18.3,
34.2, 109.5, 110.6, 112.7, 122.8, 124.0, 125.5, 126.2, 136.1 (the signals due
to the pentafluorophenyl moiety could not be assigned because of the
19
complicated multiple coupling of 13CÀ F); HRMS (ESI+) found m/z
625.34110, calcd for C33H50F5N2Si2 ([M +H]+) m/z625.34327; Rf =0.45
(hexane).
5-Pentafluorophenyl-1,9-diaza-10,11-dicarbadipyrrometh-
ane (4). To a solution of 2 (360 mg, 0.576 mmol, 1.0 equiv) in 6 mL of
+
THF was added Bu4 NFÀ (1 M in THF, 1.15 mL, 1.15 mmol, 2.0 equiv)
at ambient temperature under Ar. After stirring for 90 min, the reaction
was quenched by adding water and extracted with CH2Cl2. The
combined organic layer was washed with water, dried over Na2SO4,
and evaporated in vacuo. The residue was purified by silica gel column
chromatography using hexane/CH2Cl2 = 4/1 (v/v) as eluent. The first
19
plicated multiple coupling of 13CÀ F). Anal. Calcd for C37H17F15N4: C,
55.37; H, 2.14; N, 6.98. Found: C, 55.58; H, 2.11; N, 6.94; Rf = 0.50
(hexane/CH2Cl2 = 1/4 (v/v)).
1
fraction gave 4 as a clear oil (167 mg, 0.535 mmol, 93%): H NMR
(CDCl3, 300 MHz, ppm) δ 5.79 (s, 1H), 6.26 (br s, 2H), 6.70 (br s, 2H),
6.74À6.77 (m, 2H), 8.03 (br s, 2H); 13C NMR (CDCl3, 75 MHz, ppm)
δ 31.7, 108.3, 116.2, 117.9, 119.8*, 123.9, 137.5* (d, 1JCF = 249.8 Hz),
139.5* (d, 1JCF = 249.1 Hz), 144.8* (d, 1JCF = 243.5 Hz) (*these signals
5, 10, 15-Tris(pentafluorophenyl)-7,13-diaza-22,23-di-
carbabilane (10). NaBH4 (276 mg, 7.30 mmol, 34 equiv) was added
to a stirred solution of 6 (150 mg, 0.215 mmol, 1 equiv) in THF (16 mL)
and MeOH (6 mL) at room temperature under N2. After 3 h, the
reaction was quenched with water and diluted with CH2Cl2. Then, the
organic phase was washed with water, dried over Na2SO4, and evapo-
rated in vacuo. The resulting product (9) was used in the next step
without further purification. TFA (3.3 μL, 0.0429 mmol, 0.2 equiv) was
added to a solution of 9 in pyrrole (1.6 mL, 12.9 mmol, 60 equiv) at
room temperature under N2. After stirring for 105 min, the reaction was
quenched with 0.1 M aqueous NaOH. The organic phase was washed
with water, dried over Na2SO4, and evaporated in vacuo. The residue
19
show the further multiplet coupling due to the remote 13CÀ F
coupling.). Anal. Calcd for C15H9F5N2: C, 57.70; H, 2.91; N, 8.97.
2
Found: C, 57.97; H, 2.89; N, 9.01; Rf = 0.50 (CH Cl2).
2-Pentafluorobenzoyl-5-pentafluoropheny-1,9-diaza-10,11-
dicarbadipyrromethane (5) and 2,8-Bis(pentafluorobenzoyl)-
5-pentafluoropheny-1,9-diaza-10,11-dicarbadipyrro-methane
(6). A THF solution of EtMgBr (3.34 mL, 3.34 mmol, 1.0 M, 2.5 equiv) was
added to a stirred solution of 4 (417 mg, 1.34 mmol, 1.0 equiv) in THF
7621
dx.doi.org/10.1021/jo2014017 |J. Org. Chem. 2011, 76, 7618–7622

The Journal of Organic Chemistry
NOTE
was purifiedby silica gel column chromatography using hexane/CH2Cl2 =
1/1 (v/v) as eluent. The first fraction afforded 10 (145 mg, 84.3%): 1H
NMR (CDCl3, 300 MHz, ppm) δ 5.83 (s, 1H), 5.94 (br s, 2H), 6.04 (br s,
2H), 6.16À6.18 (m, 2H), 6.52 (br s, 2H), 6.70 (br s, 2H), 7.87 (br s, 2H),
8.06 (br s, 2H); 13C NMR (CDCl3, 75 MHz, ppm) δ 31.6, 31.7, 33.0,
107.6, 107.7, 107.9, 108.6, 116.2, 118.2, 124.0, 124.1, 124.2, 124.3, 127.8,
128.4, 128.5 (the signals due to the pentafluorophenyl moieties could not
2000, 41, 697. (e) Pawlicki, M.; Latos-Graz_yꢀnski, L.; Szterenberg, L.
J. Org. Chem. 2002, 67, 5644.
(5) Fujino, K.; Hirata, Y.; Kawabe, Y.; Morimoto, T.; Srinivasan, A.;
Toganoh, M.; Miseki, Y.; Kudo, A.; Furuta, H. Angew. Chem., Int. Ed.
2011, 50, 6855.
(6) (a) Maeda, H.; Osuka, A.; Furuta, H. J. Am. Chem. Soc. 2003,
125, 15690. (b) Furuta, H.; Maeda, H.; Osuka, A. J. Am. Chem. Soc. 2000,
122, 803. (c) Toganoh, M.; Kimura, T.; Uno, H.; Furuta, H. Angew.
Chem., Int. Ed. 2008, 47, 8913.
19
be assigned because of the complicated multiple coupling of 13CÀ F).
Anal. Calcd for C37H17F15N4: C, 55.37; H, 2.14; N, 6.98. Found: C, 55.76;
H, 2.30; N, 6.89; Rf = 0.50 (hexane/CH2Cl2 = 1/4 (v/v)).
(7) (a) Srinivasan, A.; Ishizuka, T.; Osuka, A.; Furuta, H. J. Am.
Chem. Soc. 2003, 125, 878. (b) Xie, Y.-S.; Yamaguchi, K.; Toganoh, M.;
Uno, H.; Suzuki, M.; Mori, S.; Saito, S.; Osuka, A.; Furuta, H. Angew.
Chem., Int. Ed. 2009, 48, 5496. (c) Won, D.-H.; Toganoh, M.; Terada, Y.;
Fukatsu, S.; Uno, H.; Furuta, H. Angew. Chem., Int. Ed. 2008, 47, 5438.
(d) Srinivasan, A.; Ishizuka, T.; Maeda, H.; Furuta, H. Angew. Chem., Int.
Ed. 2004, 43, 2951. (e) Sessler, J. L.; Cho, D. G.; Ste-pieꢀn, M.; Lynch, V.;
Waluk, J.; Yoon, Z. S.; Kim, D. J. Am. Chem. Soc. 2006, 128, 12640.
(8) (a) Thompson, A.; Dolphin, D. J. Org. Chem. 2000, 65, 7870. (b)
Wood, T. E.; Ross, A. C.; Dalgleish, N. D.; Power, E. D.; Thompson, A.;
Chen, X.; Okamoto, Y. J. Org. Chem. 2005, 70, 9967. (c) Dolenskꢀy, B.;
Kroulík, J.; Krꢀal, V.; Sessler, J. L.; Dvoꢁrꢀakovꢀa, H.; Bouꢁr, P.; Bernꢀatkovꢀa,
M.; Bucher, C.; Lynch, V. J. Am. Chem. Soc. 2004, 126, 13714. (d) Zhang,
Z.; Shin, J.-Y.; Dolphin, D. J. Org. Chem. 2008, 73, 9515.
(9) Bray, B. L.; Mathies, P. H.; Naef, R.; Solas, D. R.; Tidwell, T. T.;
Artis, D. R.; Muchowski, J. M. J. Org. Chem. 1990, 55, 6317.
(10) Rao, P. D.; Littler, B. J.; Geier, G. R., III; Lindsey, J. S. J. Org.
Chem. 2000, 65, 1084.
(11) Toganoh, M.; Furuta, H. J. Phys. Chem. A. 2009, 113, 13953.
(12) See Supporting Information for calculation details.
(13) (a) Formosinho, S. J.; Arnaut, L. G. J. Photochem. Photobiol. A
1993, 75, 21. (b) Doroshenko, A. O.; Posokhov, E. A.; Verezubova,
A. A.; Ptyagina, L. M.; Skripkina, V. T.; Shershukov, V. M. Photochem.
Photobiol. Sci. 2002, 1, 92. (c) Ikeda, S.; Toganoh, M.; Easwaramoorthi,
S.; Lim, J. M.; Kim, D.; Furuta, H. J. Org. Chem. 2010, 75, 8637. (d) Lee,
J. S.; Lim, J. M.; Toganoh, M.; Furuta, H.; Kim, D. Chem. Commun. 2010,
46, 285.
C-Fused Norrole (12). A 50 mL CH3CN solution of 8 (50 mg,
0.0623 mmol) and p-TsOH•H2O (3.23 mg, 0.0188 mmol) were stirred
at ambient temperature for 1 h. Then, the reaction mixture was added
dropwise to a stirred solution of DDQ (50 mg, 0.220 mmol) in CH3CN
(50 mL) under reflux. After 2 h, the solvent was evaporated in vacuo.
The residue was passed through an alumina column and further purified
by silica gel column chromatography using hexane/CH2Cl2 = 3/2 (v/v)
1
as eluent. The green fraction afforded 12 (1.0 mg, 2.0%): H NMR
(CDCl3, 300 MHz, ppm) δ 7.10À7.14 (m, 1H), 7.22 (d, J = 4.2 Hz, 1H),
7.81 (d, J = 4.2 Hz, 1H), 7.85 (d, J = 4.2 Hz, 1H), 8.05 (d, J = 4.2 Hz, 1H),
8.16À8.20 (m, 1H), 8.39 (d, J = 4.2 Hz, 1H), 8.96 (br s, 1H), 10.0 (br s,
1H); 19F NMR (CDCl3, 282 MHz, ppm) δ À136.5 (dd, J = 22.6, 6.7 Hz,
2F), À138.3 (dd, J = 22.6, 7.9 Hz, 2F), À140.5 (dd, J = 23.2, 7.3 Hz, 2F),
À151.0 (t, J = 20.8 Hz, 1F), À152.7 (t, J = 21.4 Hz, 1F), À154.9 (t, J =
21.4 Hz, 1F), À160.3 (td, J = 21.7, 6.5 Hz, 2F), À161.47 (td, J = 22.0, 7.5
Hz, 2F), À161.50 (td, J = 22.0, 7.5 Hz, 2F); (CH2Cl2, λmax/nm) 404.0,
430, 606.0; HRMS (ESIÀ) found m/z 793.04845, calcd for C37H8F15N4
([M À H]À) m/z 793.05094; Rf = 0.50 (hexane/CH2Cl2 = 1/1).
’ ASSOCIATED CONTENT
S
Supporting Information. Spectroscopic data of new
b
compounds. Details on theoretical studies and X-ray analysis.
This material is available free of charge via the Internet at http://
pubs.acs.org.
(14) (a) Schleyer, P. v. R.; Maerker, C.; Dransfeld, A.; Jiao, H.;
Hommes, N. v. E. J. Am. Chem. Soc. 1996, 118, 6317. (b) Chen, Z.;
Wannere, C. S.; Corminboeuf, C.; Puchta, R.; Schleyer, P. v. R. Chem.
Rev. 2005, 105, 3842.
’ AUTHOR INFORMATION
(15) (a) Krygowski, T. M.; Cyraꢀnski, M. Tetrahedron 1996,
52, 10255. (b) Krygowski, T. M.; Cyraꢀnski, M. Chem. Rev. 2001,
101, 1385.
Corresponding Author
*E-mail: hfuruta@cstf.kyushu-u.ac.jp.
(16) (a) Toganoh, M.; Hihara, Y.; Furuta, H. Inorg. Chem. 2010,
49, 8182. (b) Toganoh, M.; Kimura, T.; Furuta, H. Chem.—Eur. J. 2008,
14, 10585. (c) Toganoh, M.; Kimura, T.; Furuta, H. Chem. Commun.
2008, 102. (d) Gupta, I.; Srinivasan, A.; Morimoto, T.; Toganoh, M.;
Furuta, H. Angew. Chem., Int. Ed. 2008, 47, 4563.
’ ACKNOWLEDGMENT
The present work was supported by the Grant-in-Aid for
Scientific Research (21750047, 21108518, and 22350020) and
the Global COE Program “Science for Future Molecular Sys-
tems” from the Ministry of Education, Culture, Sports, Science
and Technology of Japan.
’ REFERENCES
(1) (a) Gryko, D. T. Eur. J. Org. Chem. 2002, 1735. (b) Aviv-Harel, I.;
Gross., Z. Chem.—Eur. J. 2009, 15, 8382. (c) Gryko, D. T. J. Porphyrins
Phthalocyanines 2008, 12, 906. (d) Roberto, P. Synlett 2008, 2215. (e)
Gryko, D. T.; Fox, J. P.; Goldberg, D. P. J. Porphyrins Phthalocyanines
2004, 8, 1091.
(2) (a) Gross, Z. J. Biol. Inorg. Chem. 2001, 6, 733. (b) Ghosh, A.;
Steene, E. J. Biol. Inorg. Chem. 2001, 6, 739.
(3) (a) Aviv, I.; Gross, Z. Chem. Commun. 2007, 1987. (b) Gross, Z.;
Gray, H. B. Adv. Synth. Catal. 2004, 346, 165. (c) Aviv-Harel, I.; Gross, Z.
Chem. ÀEur. J. 2009, 15, 8382.
(4) (a) Furuta, H.; Maeda, H.; Osuka, A. J. Am. Chem. Soc. 2001,
123, 6435. (b) Shetti, V. S.; Prabhu, U. R.; Ravikanth, M. J. Org. Chem.
2010, 75, 4172. (c) Narayanan, S. J.; Sridevi, B.; Chandrashekar, T. K.
Org. Lett. 1999, 1, 587. (d) Cho, W.-S.; Lee, C.-H. Tetrahedron Lett.
7622
dx.doi.org/10.1021/jo2014017 |J. Org. Chem. 2011, 76, 7618–7622