Facile and efficient hypervalent iodine(III)-mediated meso- functionalization of porphyrins

Article abstract of DOI:10.1021/jo801855d

(Chemical Equation Presented) Highly facile and efficient synthesis of a variety of meso-functionalized porphyrins was accomplished by PhI(OAc) ₂-NaAuCl₄ mediated direct nucleophilic substitution reactions of [5,10,15-triphenylporphy

Full text of DOI:10.1021/jo801855d

Facile and Efficient Hypervalent Iodine(III)-Mediated
meso-Functionalization of Porphyrins
Dong-Mei Shen, Chao Liu, Xiao-Guang Chen, and Qing-Yun Chen*
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy
of Sciences, 354 Fenglin Road, Shanghai 200032, China
chenqy@mail.sioc.ac.cn
ReceiVed August 20, 2008
Highly facile and efficient synthesis of a variety of meso-functionalized porphyrins was accomplished
by PhI(OAc)2-NaAuCl4 mediated direct nucleophilic substitution reactions of [5,10,15-triphenylporphy-
rinato]zinc(II) (Zn1) with different amines and thiophenols. When [5,15-dibromo-10,20-diphenylpor-
phyrinato]zinc(II) (Zn12) was used as the starting porphyrin under similar conditions, the double
nucleophilic substitution products were obtained in good yields.
Introduction
conditions they do undergo oxidative coupling reactions af-
fording various interesting and useful directly fused porphyrin
arrays5,6 or react with some nucleophiles providing the corre-
sponding ꢀ- and meso-substituted porphyrins.7 With these in
mind, we developed a facile and efficient hypervalent iodine(III)-
mediated nucleophilic substitution reaction for direct and
convenient synthesis of a wide range of meso-amino or meso-
arylsulfanyl-substituted porphyrins. Herein the results are
presented.
Functionalization of porphyrins has always attracted much
interest because it is the main foundation of modulating various
properties of the porphyrin macrocycle and further constructing
new and valuable porphyrins. To address this issue, a large
number of methods have been developed.1 Among them,
transition metal-catalyzed reactions of halogenated porphyrins
represent recent considerable progress and enable convenient
and quick installation of a variety of potentially useful porphy-
rins, despite the need for prefunctionalization of the porphyrin
macrocycle.2-4 To the best of our knowledge, no reports on
direct synthesis of the above porphyrins have appeared so far.
π-Radical cations of metalloporphyrins are readily generated
by their reactions with various oxidants. They are relatively
stable due to the delocalization of the unpaired electron over
the π-electron system of the macrocycle. But under appropriate
Results and Discussion
Hypervalent iodine(III) reagents, such as phenyliodine diac-
etate (PIDA) and phenyliodine di(trifluoroacetate) (PIFA), have
(3) (a) Liu, C.; Shen, D.-M.; Chen, Q.-Y. J. Org. Chem. 2007, 71, 2734. (b)
Shen, D.-M.; Liu, C.; Chen, Q.-Y. Synlett 2007, 3068. (c) Liu, C.; Shen, D.-M.;
Chen, Q.-Y. Chem. Commun. 2006, 770. (d) Shen, D.-M.; Liu, C.; Chen, Q.-Y.
J. Org. Chem. 2006, 71, 6508. (e) Liu, C.; Shen, D.-M.; Zeng, Z.; Guo, C.-C.;
Chen, Q.-Y. J. Org. Chem. 2006, 71, 9772. (f) Liu, C.; Shen, D.-M.; Chen,
Q.-Y. Eur. J. Org. Chem. 2006, 2703. (g) Liu, C.; Chen, Q.-Y. Synlett 2005,
1306. (h) Liu, C.; Chen, Q.-Y. Eur. J. Org. Chem. 2005, 3680. (i) Shen, D.-M.;
Liu, C.; Chen, Q.-Y. Chem. Commun. 2005, 4982.
(1) The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R.,
Eds.; Academic Press: San Diego, CA, 2000-2003, Vols. 1-20.
(2) For relevant reviews, see:(a) Senge, M. O.; Richter, J. J. Porphyrins
Phthalocyanines 2004, 8, 934. (b) Sharman, W. M.; Van Lier, J. E. J. Porphyrins
Phthalocyanines 2000, 4, 441.
206 J. Org. Chem. 2009, 74, 206–211
10.1021/jo801855d CCC: $40.75 2009 American Chemical Society
Published on Web 11/19/2008

I(III)-Mediated meso-Functionalization of Porphyrins
TABLE 1. Nucleophilic Substitution Reactions of Zn1 with 2a under Various Conditionsa
yield (%)b
Zn3a
entry
oxidant/additive (equiv)
PIFA (1)
PIFA (3)
PIDA (1)
PIDA (3)
PIDA (1)
PIDA (1)
PIDA (1)
PIDA (1)
PIDA (1)
PIDA (1)
DDQ (1)
DDQ (10)
AgPF6 (1)
NaAuCl4 ·2H2O (1)
PIDA (1)
base
solvent
CH2Cl2
T (°C)
t (h)
Zn4
1
2
3
4
5
6
7
8
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
KOH
25
25
25
25
25
25
25
25
40
25
25
25
25
25
84
110
25
25
25
25
25
25
2
2
2
2
2
2
2
2
2
48
2
0.5
0.5
0.5
2
2
2
2
10c
0
30
0
0
0
0
0
0
0
0
0
0
85
93
0
0
0
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
ClCH2CH2Cl
toluene
THF
5d
25c
25c
25c
25c
25c
25c
25c
40f
0g
K2CO3
Et3N
e
-
e
9
-
e
10
11
12
13
14
15
16
17
18
19
20
21
22
-
e
-
e
-
0d
0
e
-
e
-
0
e
-
25c
25c
0g
e
PIDA (1)
PIDA (1)
-
e
-
e
PIDA/FeCl3 ·6H2O (1:1)
PIDA/NaAuCl4 ·2H2O (1:1)
PIDA/NaAuCl4 ·2H2O (1.5:1)
PIDA/NaAuCl4 ·2H2O (1:1.5)
PIDA/NaAuCl4 ·2H2O (1:2)
-
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
55
65
55
92
92
40
25
40
5
e
-
0.5
0.5
0.5
0.5
e
-
e
-
e
-
5
a Reactions were carried out in solvent (10 mL) with Zn1 (30 mg, 1.0 equiv), 2a (5.0 equiv), and base (5.0 equiv) in air in the presence of an
oxidant. b Isolated yields. c Recovery of Zn1: 70-85%. d Serious degradation of porphyrin was observed. e No base was used. f Recovery of Zn1:
∼55%. g No reaction occurred. Recovery of Zn1: ∼95%.
been extensively employed in organic synthesis as popular and
useful oxidants due to their unique and beneficial properties.8
Our group recently reported efficient synthesis of various directly
fused porphyrin arrays promoted by them via porphyrin cation
radical intermediates.5 In connection with these investigations,
we attempted to conduct the direct nucleophilic substitution
reaction of [5,10,15-triphenylporphyrinato]zinc(II) (Zn1) with
4-methylaniline (2a) in the presence of different hypervalent
iodine(III) reagents. The detailed results are listed in Table 1.
We were delighted to find that the reaction utilizing PIDA or
(4) For recent and selective reports, see:(a) Gao, G.-Y.; Ruppel, J. V.; Fields,
K. B.; Xu, X.; Chen, Y.; Zhang, X. P. J. Org. Chem. 2008, 73, 4855. (b) Gao,
G.-Y.; Ruppel, J. V.; Allen, D. B.; Chen, Y.; Zhang, X. P. J. Org. Chem. 2007,
72, 9060. (c) Chen, Y.; Gao, G.-Y.; Zhang, X. P. Tetrahedron Lett. 2005, 46,
4965. (d) Chen, Y.; Fields, K. B.; Zhang, X. P. J. Am. Chem. Soc. 2004, 126,
14718. (e) Gao, G. Y.; Colvin, A. J.; Chen, Y.; Zhang, X. P. J. Org. Chem.
2004, 69, 8886. (f) Gao, G. Y.; Chen, Y.; Zhang, X. P. Org. Lett. 2004, 6, 1837.
(g) Gao, G. Y.; Colvin, A. J.; Chen, Y.; Zhang, X. P. Org. Lett. 2003, 5, 3261.
(h) Gao, G. Y.; Chen, Y.; Zhang, X. P. J. Org. Chem. 2003, 68, 6215. (i) Chen,
Y.; Zhang, X. P. J. Org. Chem. 2003, 68, 4432. (j) Soares, A. R. M.; Martinez-
Diaz, M. V.; Bruckner, A.; Pereira, A. M. V. M.; Tome, J. P. C.; Alonso,
C. M. A.; Faustino, M. A. F.; Neves, M. G. P. M. S.; Tome, A. C.; Silva,
A. M. S.; Cavaleiro, J. A. S.; Torres, T.; Guldi, D. M. Org. Lett. 2007, 9, 1557.
(k) Matano, Y.; Matsumoto, K.; Terasaka, Y.; Hotta, H.; Araki, Y.; Ito, O.; Shiro,
M.; Sasamori, T.; Tokitoch, N.; Imahori, H. Chem. Eur. J. 2007, 13, 891. (l)
Matano, Y.; Shinokura, T.; Matsumoto, K.; Imahori, H.; Nakano, H. Chem. Asian
J. 2007, 2, 1417. (m) Weng, Y.-Q.; Yue, F.; Zhong, Y.-R.; Ye, B.-H. Inorg.
Chem. 2007, 46, 7749. (n) Esdaile, L. J.; Senge, M. O.; Arnold, D. P. Chem.
Commun. 2006, 4192. (o) Atefi, F.; McMurtrie, J. C.; Duriska, M.; Turner, P.;
Arnold, D. P. Inorg. Chem. 2006, 45, 6479. (p) Peters, M. V.; Goddard, R.;
Hecht, S. J. Org. Chem. 2006, 71, 7846. (q) Esdaile, L. J.; McMurtrie, J. C.;
Turner, P.; Arnold, D. P. Tetrahedron Lett. 2005, 46, 6931. (r) Frampton, M. J.;
Akdas, H.; Cowley, A. R.; Rogers, J. E.; Slagle, J. E.; Fleitz, P. A.; Drobizhev,
M.; Rebane, A.; Anderson, H. L. Org. Lett. 2005, 7, 5365. (s) Takanami, T.;
Hayashi, M.; Hino, F.; Suda, K. Tetrahedron Lett. 2003, 44, 7353. (t) Cheng,
L. L.; Chang, C. J.; Nocera, D. G. J. Org. Chem. 2003, 68, 4075. (u) Khan,
M. M.; Ali, H.; Van Lier, J. E. Tetrahedron Lett. 2001, 42, 1615. (v) Vas, B.;
Alvarez, R.; Nieto, M.; Paniello, A. I.; de Lera, A. R. Tetrahedron Lett. 2001,
42, 7409. (w) Deng, Y.; Chang, C. K.; Nocera, D. G. Angew. Chem., Int. Ed.
2000, 39, 1066. (x) Iovine, P. M.; Kellett, M. A.; Redmore, N. P.; Therien,
M. J. J. Am. Chem. Soc. 2000, 122, 8717. (y) Shanmugathasan, S.; Johnson,
C. K.; Edwards, C.; Matthews, E. K.; Dolphin, D.; Boyle, R. W. J. Porphyrins
Phthalocyanines 2000, 4, 228. (z) Shi, X.; Amin, R.; Liebeskind, L. S. J. Org.
Chem. 2000, 65, 1650.
(5) (a) Jin, L.-M.; Chen, L.; Yin, J.-J.; Guo, C.-C.; Chen, Q.-Y. Eur. J. Org.
Chem. 2005, 3994. (b) Jin, L.-M.; Yin, J.-J.; Chen, L.; Guo, C.-C.; Chen, Q.-Y.
Synlett 2005, 2893.
(6) For some examples of the leading reports, see:(a) Osuka, A.; Shimidzu,
H. Angew. Chem., Int. Ed. Engl. 1997, 36, 135. (b) Ogawa, T.; Nishimoto, Y.;
Yoshida, N.; Ono, N.; Osuka, A. Chem. Commun. 1998, 337. (c) Tsuda, A.;
Osuka, A. Science 2001, 293, 79. (d) Sahoo, A. K.; Nakamura, Y.; Aratani, N.;
Kim, K. S.; Noh, S. B.; Shinokubo, H.; Kim, D.; Osuka, A. Org. Lett. 2006, 8,
4141. (e) Nakamura, Y.; Aratani, N.; Shinokubo, H.; Takagi, A.; Kawai, T.;
Matsumoto, T.; Yoon, Z. S.; Kim, D. Y.; Ahn, T. K.; Kim, D.; Muranaka, A.;
Koayashi, N.; Osuka, A. J. Am. Chem. Soc. 2006, 128, 4119, and references
cited therein. (f) Shi, X.; Amin, S. R.; Liebeskind, L. S. J. Org. Chem. 2000,
65, 1665.
(7) (a) Jaquinod, L. In The Porphyrin Handbook; Kadish, K. M., Smith,
K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000; Vol. 1, Chapter
5, pp 201-238. (b) Vicente, M. G. H. In The Porphyrin Handbook; Kadish,
K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000;
Vol. 1, Chapter 4, pp 149-199. (c) Padilla, A. G.; Wu, S.-M.; Shine, H. J.
J. Chem. Soc., Chem. Commun. 1976, 236. (d) Shine, H. J.; Padilla, A. G.; Wu,
S.-M. J. Org. Chem. 1979, 44, 4069. (e) Smith, K. M.; Barnett, G. H.; Evans,
B.; Martynenko, Z. J. Am. Chem. Soc. 1979, 101, 5953. (f) Giraudeau, A;
Ruhlmann, L.; Kahef, L. E.; Gross, M. J. Am. Chem. Soc. 1996, 118, 2926.
(8) For selective leading reviews, see:(a) Wirth, T. Angew. Chem., Int. Ed.
2005, 44, 3656. (b) Moriarty, R. M. J. Org. Chem. 2005, 70, 2893. (c) Zhdankin,
V. V.; Stang, P. J. Chem. ReV. 2002, 102, 2523. (d) HyperValent Iodine
Chemistry; Wirth, T., Ed.; Springer-Verlag: Berlin, Germany, 2003.
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Shen et al.
TABLE 2. Nucleophilic Substitution Reactions of Zn1 with Various Amine 2a
a Reactions were carried out in CH2Cl2 (10 mL) with Zn1 (30 mg, 1.0 equiv) and 2 (5.0 equiv) in air at room temperature for 30 min in the presence
of PIDA-NaAuCl4 ·2H2O (1:1.5 equiv). b Isolated yields. c Recovery of Zn1: ∼25%. d Recovery of Zn1: 40-50%.
PIFA as an oxidant in dichloromethane successfully resulted
in the desired nucleophilic substitution product Zn3a without
notable formation of the oxidative coupling product Zn4,
although the yields were low (Table 1, entries 1-4). The use
of base and an elevated temperature proved unnecessary for the
reaction because similar results were obtained in its absence or
at higher temperature (Table 1, entries 1-9). Extended reaction
time facilitated the reaction since the conversion obviously
increased after 48 h (Table 1, entry 10). When using other
oxidants instead of PIDA or PIFA, such as DDQ, AgPF6, and
NaAuCl4 ·2H2O, no desired nucleophilic substitution product
Zn3a was formed under analogous conditions (Table 1, entries
11-14). Additionally, a significant solvent effect on the reaction
was also observed. Noncoordinating solvents 1,2-dichlo-
romethane or toluene led to similar results, whereas no reaction
occurred with the use of THF, which is in line with the literature
(Table 1, entries 15-17).6f
BF3 ·Et2O, AlCl3, Cu(OAc)2 ·H2O, AgPF6, I2, Ce(SO4)2 ·4H2O,
Na2S2O8, NaIO4, and PIFA, on the nucleophilic substitution reaction
were very slight (see the Supporting Information). When
FeCl3 ·6H2O was used as an additive, noticeable improvement in
the conversion and yield was observed, though a considerable
amount of the oxidative coupling product Zn4 was formed (Table
1, entry 18). Finally, NaAuCl4 ·2H2O was proven a superior
additive, giving good yield of the desired nucleophilic substitution
product Zn3a and a small amount of Zn4 in shorter reaction time
(30 min) (Table 1, entry 19). Further investigations indicated that
excellent yield of Zn3a and a trace of Zn4 were obtained by
controlling the equivalents of PIDA and NaAuCl4 ·2H2O (Table
1, entry 20-22). On the basis of these results, the nucleophilic
substitution reactions were successfully conducted in dichlo-
romethane at room temperature in the presence of PIDA-
NaAuCl4 ·2H2O (1:1.5 equiv). Moreover, there is no need for dried
solvent and nitrogen protection.
With the optimal conditions in hand, we carried out the
reactions of Zn1 with various aryl and aliphatic amines.
Representative results are summarized in Table 2. A number
of primary anilines with different substituents were efficiently
applied to the direct nucleophilic substitution reactions, generally
furnishing the desired necleophilic substitution products in good
yields with small amounts of the oxidative coupling product
Zn4 (Table 2, entries 1-7). The secondary N-methylaniline was
also a suitable coupling partner for the reaction, providing
similar good yield of the desired product (Table 2, entry 8).
Encouraged by these preliminary results, we decided to further
optimize the reaction conditions by adding some additives because
it was reported that additives, especially Lewis acids, exercised a
great influence on the activity of hypervalent iodine(III) reagents
and the reaction course.8,9 The influences of additives, such as
(9) (a) Dohi, T.; Ito, M.; Iwata, M.; Kita, Y. Angew. Chem., Int. Ed. 2008,
47, 1301. (b) Dohi, T.; Morimoto, K.; Maruyama, A.; Kita, Y. Org. Lett. 2006,
8, 2007. (c) Dohi, T.; Morimoto, K.; Kiyono, Y.; Maruyama, A.; Tohma, H.;
Kita, Y. Chem. Commun. 2005, 2930. (d) Kar, A.; Mangu, N.; Kaiser, H. M.;
Beller, M.; Tse, M. K. Chem. Commun. 2008, 386.
208 J. Org. Chem. Vol. 74, No. 1, 2009

I(III)-Mediated meso-Functionalization of Porphyrins
TABLE 3. Nucleophilic Substitution Reactions of Zn1 with Various Thiophenols 5a
yieldb(%)
entry
reactant
t (h)
product
H26
H21
1
2
3
4
5
5a
5b
5c
5d
5e
2
2
4
4
4
H26a
H26b
H26c
H26d
H26e
65
70
50
60
40
15
15
35
25
40
a Reactions were carried out in CH2Cl2 (10 mL) with Zn1 (30 mg, 1.0 equiv) and 5 (5.0 equiv) in air at room temperature in the presence of
PIDA-NaAuCl4 ·2H2O (1:1.5 equiv). b Isolated yields.
SCHEME 1
The uses of secondary aliphatic amines only led to the
nucleophilic substitution products besides the recovered starting
porphyrin and no oxidative coupling product Zn4 was observed
(Table 2, entries 9-12).
We then tried to expand the scope of the nucleophilic substitution
reaction by subjecting a variety of thiophenols to the reaction. As
demonstrated in Table 3, thiophenols with both electron-donating
and electron-withdrawing substituents were easily reacted with Zn1,
resulting in acceptable yields of the desired nucleophilic substitution
products without formation of the oxidative coupling product,
though a small amount of the demetalated starting porphyrin H21
was obtained. It should be mentioned that central zinc ions in the
nucleophilic substitution products left during the reaction probably
due to the presence of excess amounts of thiophenols and acids in
the reaction system, which is consistent with the previous reports.10
The relatively lower yields might be attributed to the demetalation
J. Org. Chem. Vol. 74, No. 1, 2009 209

Shen et al.
TABLE 4. Double Nucleophilic Substitution Reactions of meso-Dibromoporphyrin Zn12 with Various Amines and Thiophenolsa
a Reactions were carried out in CH2Cl2 (10 mL) with Zn12 (30 mg, 1.0 equiv) and 2 or 5 (5.0 equiv) in air in the presence of PIDA-NaAuCl4 ·2H2O
(1:1.5 equiv). b Isolated yields.
of the starting porphyrin, which results in higher oxidation potential.
This was further supported by the fact that no reaction occurred
when utilizing free-base porphyrin H21 as the starting porphyrin
under similar conditions.
Next, we examined the nucleophilic substitution reaction of
[5,15-diphenylporphyrinato]zinc(II) (Zn7)3c with 4-methylaniline
(2a) and thiophenol 5a under the similar conditions, expecting to
obtain the double nucleophilic substitution products. However, the
reaction with 2a resulted in a complex mixture including various
porphyrin oligomers (Scheme 1). In the case of 5a, the demetalated
starting porphyrin H27 was observed in addition to a trace of
demetalated mononucleophilic substitution product H28 (Scheme
1). In view of the important role of bromoporphyrins as building
(10) (a) Battersby, A. R.; Jones, K.; Snow, R. J. Angew. Chem., Int. Ed.
Engl. 1983, 22, 734. (b) Lewis, N. J.; Pfaltz, A.; Eschenmoser, A. Angew. Chem.,
Int. Ed. Engl. 1983, 22, 735.
210 J. Org. Chem. Vol. 74, No. 1, 2009

I(III)-Mediated meso-Functionalization of Porphyrins
SCHEME 2. Proposed Reaction Mechanism for the PIDA-NaAuCl4-Mediated Nucleophilic Substitution Reactions
blocks for easy construction of various novel and useful porphy-
rins,2-4 we decided to use [5-bromo-10,20-diphenylporphyrina-
to]zinc(II) (Zn9) as an alternative starting porphyrin. Surprisingly,
its reaction with 2a did not lead to the expected mononucleophilic
substitution product Zn10, but the double nucleophilic substitution
product Zn11 in high yield, indicating that the meso-bromine atom
cannot be retained in the reaction (Scheme 1). Considering the
relatively ready availability of meso-dibromoporphyrin, [5,15-
dibromo-10,20-diphenylporphyrinato]zinc(II) (Zn12) was used for
the following double nucleophilic substitution reactions. As il-
lustrated in Table 4, various aromatic amines and thiols could be
well transformed, affording good yields of the double nucleophilic
substitution products.
free meso position by PIDA-NaAuCl4-mediated nucleophilic
substitution reactions, which allows quick and easy access to a
wide range of meso-amino or meso-arylsulfanyl-substituted
porphyrins. The use of noncoordinating solvents and
NaAuCl4 ·2H2O as an additive are critical for the reaction. This
protocol can also be applied to meso-dibromoporphyrin, provid-
ing the corresponding double nucleophilic substitution products
in good yields.
Experimental Section
General Procedure for PhI(OAc)2-NaAuCl4-Mediated
Nucleophilic Substitution Reactions of Zn1 with Various
Amines 2 or Thiophenols 5. Porphyrin Zn1 (30 mg, 0.05 mmol,
1.0 equiv), amine 2 or thiophenol 5 (5.0 equiv), PIDA (16 mg, 1.0
equiv), and NaAuCl4 ·2H2O (30 mg, 1.5 equiv) were added to a
round-bottomed bottle and CH2Cl2 (10 mL) was charged. The
reaction mixture was stirred in air at room temperature for 30-240
min. Then a saturated solution of Na2S2O3 (10 mL) was added.
After being stirred for 10 min, the reaction mixture was washed
with water three times. The organic layer was collected, filtered
through dry silica gel, and evaporated to dryness. The resulting
solid was purified by flash chromatography to give the desired
nucleophilic substitution products in good yields.
On the basis of the above results and the literature,5,6,9
a
possible reaction mechanism for the PIDA-NaAuCl4-mediated
nucleophilic substitution reaction was outlined in Scheme 2.
The combination of PIDA and the porphyrin macrocycle
generates the charge-transfer complex A1, which further forms
the charge-transfer complex A2 by coordination of gold(III)
cation with the acetate anion in A1. The key intermediate
porphyrin radical cation B is subsequently produced via the
single-electron transfer (SET) oxidation. In situ trapping of
radical cation B by nucleophiles followed by further oxidation
and deprotonation/debromination results in the formation of
nucleophilic substitution products (path A). At the same time,
the porphyrin cation radical B might dimerize to form the
intermediate C, which leads to the oxidative coupling product
Zn4 after deprotonation (path B).
Acknowlegement. We thank the Natural Science Foundation
of China (Nos. 20772146, 20272026, D20032010, and 20532040)
for supporting this work.
Supporting Information Available: Experimental details,
1
characterization data, and copies of H and 19F NMR spectra
Conclusions
of all new porphyrins. This material is available free of charge
via the Internet at http://pubs.acs.org.
In summary, we have developed a facile and efficient
synthesis of various meso-functionalized porphyrins directly
from [5,10,15-triphenylporphyrinato]zinc(II) (Zn1) with a single
JO801855D
J. Org. Chem. Vol. 74, No. 1, 2009 211