Porphyrins with exocyclic rings. 11.1 Synthesis and characterization of phenanthroporphyrins, a new class of modified porphyrin chromophores

Article abstract of DOI:10.1021/jo980043m

To obtain insights into the factors that influence the electronic spectra of conjugated porphyrin systems, a series of porphyrins with fused phenanthrene subunits have been synthesized. 9-Nitrophenanthrene reacted with esters of isocyanoacetic acid in the presence of DBU in THF to give a series of phenanthro[9,10-c]pyrroles 14 in good to excellent yields, and subsequent acid-catalyzed condensation with various (acetoxymethyl)pyrroles 18 gave six examples of dipyrryl-methanes 17 that incorporate a fused phenanthrene ring. Cleavage of the benzyl esters from 17a by hydrogenolysis over 10% Pd/C gave the corresponding dicarboxylic acid 24 and this condensed with diformyldipyrrylmethanes 22 under modified MacDonald '2 + 2' condensation conditions to afford the monophenanthroporphyrins 19 and 20. Dipyrrylmethanes 17d and 17f with mixed benzyl and tert-butyl ester moieties were converted into the related formyl dipyrrylmethanecarboxylic acids 29, and subsequent head-to-tail self-condensation in the presence of p-toluenesulfonic acid yielded two examples of opp-diphenanthroporphyrins 27. Reaction of phenanthropyrroles 14 with dimenthoxymethane and p-toluenesulfonic acid in acetic acid afforded the symmetrical dipyrrl-methanes 31, and following cleavage of the ester moieties and MacDonald condensation with dialdehyde 22b, the adj-diphenanthroporphyrin 30 was isolated in moderate yield. Metal chelates of the mono-, opp-di, and adj-diphenanthroporphyrin systems were also prepared, and the electronic spectra for these modified porphyrin systems and their nickle(II), copper(II), and zinc complexes were examined. Surprisingly, the UV-vis absorptions were only slightly shifted to higher wavelengths than those for octaalkylporphyrins. Reduction of ethyl ester 14a with lithium aluminum hydride gave an unstable carbinol, and subsequent tetramerization in the presence of BF₃ etherate and oxidation with DDQ afforded the tetraphenanthroporphyrin 10. The free base porphyrin was virtually insoluble in organic solvents, but protonation with TFA gave a soluble dication 10H₂²⁺ with a strong Soret band at 482 nm and two weaker absorptions at 615 and 668 nm. The bathochromic shifts for 10H₂²⁺ are far more significant than those observed for the mono- and diphenanthroporphyrin structures, although again somewhat less than might have been expected for this extraordinarily high degree of ring fusion.

Full text of DOI:10.1021/jo980043m

3998
J . Org. Chem. 1998, 63, 3998-4010
P or p h yr in s w ith Exocyclic Rin gs. 11.1 Syn th esis a n d
Ch a r a cter iza tion of P h en a n th r op or p h yr in s, a New Cla ss of
Mod ified P or p h yr in Ch r om op h or es
Bennett H. Novak and Timothy D. Lash*
Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160
Received J anuary 8, 1998
To obtain insights into the factors that influence the electronic spectra of conjugated porphyrin
systems, a series of porphyrins with fused phenanthrene subunits have been synthesized.
9-Nitrophenanthrene reacted with esters of isocyanoacetic acid in the presence of DBU in THF to
give a series of phenanthro[9,10-c]pyrroles 14 in good to excellent yields, and subsequent acid-
catalyzed condensation with various (acetoxymethyl)pyrroles 18 gave six examples of dipyrryl-
methanes 17 that incorporate a fused phenanthrene ring. Cleavage of the benzyl esters from 17a
by hydrogenolysis over 10% Pd/C gave the corresponding dicarboxylic acid 24 and this condensed
with diformyldipyrrylmethanes 22 under modified MacDonald “2 + 2” condensation conditions to
afford the monophenanthroporphyrins 19 and 20. Dipyrrylmethanes 17d and 17f with mixed benzyl
and tert-butyl ester moieties were converted into the related formyl dipyrrylmethanecarboxylic
acids 29, and subsequent head-to-tail self-condensation in the presence of p-toluenesulfonic acid
yielded two examples of opp-diphenanthroporphyrins 27. Reaction of phenanthropyrroles 14 with
dimethoxymethane and p-toluenesulfonic acid in acetic acid afforded the symmetrical dipyrryl-
methanes 31, and following cleavage of the ester moieties and MacDonald condensation with
dialdehyde 22b, the adj-diphenanthroporphyrin 30 was isolated in moderate yield. Metal chelates
of the mono-, opp-di-, and adj-diphenanthroporphyrin systems were also prepared, and the electronic
spectra for these modified porphyrin systems and their nickel(II), copper(II), and zinc complexes
were examined. Surprisingly, the UV-vis absorptions were only slightly shifted to higher
wavelengths than those for octaalkylporphyrins. Reduction of ethyl ester 14a with lithium
aluminum hydride gave an unstable carbinol, and subsequent tetramerization in the presence of
BF3 etherate and oxidation with DDQ afforded the tetraphenanthroporphyrin 10. The free base
porphyrin was virtually insoluble in organic solvents, but protonation with TFA gave a soluble
2+
dication 10H2 with a strong Soret band at 482 nm and two weaker absorptions at 615 and 668
nm. The bathochromic shifts for 10H22+ are far more significant than those observed for the mono-
and diphenanthroporphyrin structures, although again somewhat less than might have been
expected for this extraordinarily high degree of ring fusion.
In tr od u ction
benzo units.4 The importance of the phthalocyanines has
led to the synthesis of related “conjugated macrocycles”,5
including naphthocyanines (3),6 and hybrid structures
such as tetrabenzoporphyrin (4),7 tetraazaporphyrins
(porphyrazines; 5),8 and macrocycles with an intermedi-
ary number of bridging nitrogen atoms.9 The stunning
array of applications for phthalocyanines and naphtho-
cyanines in material science and elsewhere has led to the
The phthalocyanines (1) are among the best studied
classes of organic pigments and have a myriad of
industrial applications that result in the production of
hundreds of successful patent applications each year.2
They are commonly used as dyes and inks, but are also
finding novel applications in the development of optical
materials (photovoltaics, nonlinear optics, xerography,
solar cells, optical memory and data storage, sensors,
etc.), catalysts and electrical conductors.2 Alongside the
porphyrins, they also have suitable properties to act as
photosensitizers in photodynamic therapy (PDT).3 In
addition, the molecular architecture of the phthalocya-
nines may lead to unique possibilities in molecular
recognition studies and nanotechnology. In structural
terms, phthalocyanines (1) are closely related to the
porphyrins (2), and differ by (a) having bridging nitrogens
instead of carbon linkages and (b) possessing four fused
(4) Moser, F. H.; Thomas, A. L. In Phthalocyanine Compounds;
Reinhold Publishing Corp.: New York, 1963; pp 1-13. Linstead, R. P.
J . Chem. Soc. 1934, 1016.
(5) Linstead, R. P. J . Chem. Soc. 1953, 2873.
(6) Bradbrook, E. F.; Linstead, R. P. J . Chem. Soc. 1936, 1744.
(7) Helberger, J . H.; Hever, D. B. Ann. 1938, 536, 173. Linstead, R.
P.; Noble, E. G. J . Chem. Soc. 1937, 933. Linstead, R. P.; Rowe, G. A.
J . Chem. Soc. 1940, 1070. Linstead, R. P.; Weiss, F. T. J . Chem. Soc.
1950, 2975. Bender, C. O.; Bonnett, R.; Smith, R. G. J . Chem. Soc. (C)
1970, 1251. Bender, C. O.; Bonnett, R.; Smith, R. G. J . Chem. Soc.,
Perkin Trans. 1 1972, 771. Edwards, L.; Gouterman, M.; Rose, C. B.
J . Am. Chem. Soc. 1976, 98, 7638. Vogler, A.; Kunkely, H. Angew.
Chem., Int. Ed. Engl. 1978, 17, 7, 760. Koehorst, R. B. M. et al. J .
Chem. Soc., Perkin Trans. 2 1981, 1005. Remy, D. E. Tetrahedron Lett.
1983, 24, 1451. Vincente, M. G. H.; Tome´, A. C.; Walter, A.; Cavaleiro,
J . A. S. Tetrahedron Lett. 1997, 38, 3639.
(8) Cook, A. H.; Linstead, R. P. J . Chem. Soc. 1937, 929. Linstead,
R. P.; Whalley, M. J . Chem. Soc. 1952, 4839. Ficken, G. E.; Linstead,
R. P. Ibid. 4846. Baguley, M. E.; France, H.; Linstead, R. P.; Whalley,
M. J . Chem. Soc. 1955, 3521. Brown, P. M.; Spiers, D. B.; Whalley, M.
J . Chem. Soc. 1957, 2882.
* Corresponding author. E-mail: tdlash@rs6000.cmp.ilstu.edu.
(1) Part 10: Lash, T. D. Tetrahedron 1998, 54, 359.
(2) Phthalocyanines: Properties and Applications; Leznoff, C. C., Ed.;
VCH Publishers: New York, 1990-1996; Vol. 1-4.
(3) Brown, S. B.; Truscott, T. G. Chem. Br. 1993, 29, 955. Bonnett,
R. Chem. Soc. Rev. 1995, 24, 19.
S0022-3263(98)00043-7 CCC: $15.00 © 1998 American Chemical Society
Published on Web 05/20/1998

Porphyrins with Exocyclic Rings
Ch a r t 1. Con ju ga ted Ma cr ocycles
J . Org. Chem., Vol. 63, No. 12, 1998 3999
structures of this type may be generated by the modifica-
tion of preformed porphyrin structures, and this approach
has been applied by Crossley and co-workers to the
development of so-called molecular wires.14 We have
recently synthesized benzo- (e.g. 8)16 and naphthopor-
phyrins (e.g. 9)17,18 of potential geochemical significance
by first preparing monopyrrolic precursors bearing the
required fused ring system. In extending the conjuga-
tion, it had been anticipated that the UV-vis absorption
bands in naphthoporphyrin 9 would be significantly
shifted to higher wavelength compared to 8, a charac-
teristic that would be valuable in medicinal (PDT) and
material science applications. However, the observed
bathochromic shifts were minor,17 even when two naph-
thalene subunits were introduced.18 In an attempt to
gain further insights into the factors that influence the
electronic spectra of conjugated porphyrin systems, we
were interested in extending these investigations to the
synthesis of porphyrins with fused phenanthrene rings
(e.g. 10).19,20 While we were hopeful that these new
systems would exhibit red shifted chromophores, the
principle motivation for this work was to observe the
effect of further conjugation on the porphyrin nucleus.
However, these planar porphyrinoid structures might
have value in other respects by virtue of their altered
dimensions and geometries, and therefore could find
utility in molecular recognition studies.
Resu lts a n d Discu ssion
A prerequisite for these studies was the availability of
suitably substituted phenanthropyrroles. In the synthe-
sis of naphthoporphyrin 9,17a the key dihydronaphtho-
pyrrole intermediates were prepared by application of a
Knorr-type pyrrole condensation.21 However, this ap-
proach was not viable for the preparation of pyrroles with
fused phenanthrene subunits. A valuable and popular
approach to pyrrole synthesis was introduced by Barton
and Zard in 1985 where readily available nitroalkenes
(11) are condensed with isocyanoacetate esters in the
presence of a nonnucleophilic base such as DBU (Scheme
1).22-24 This involves the Michael addition of an enolate
ion to the nitroalkene, followed by cyclization onto the
synthesis of more extended structures such as 6,10 as well
as less symmetrical macrocyles.2 However, the study of
true porphyrins with fused conjugated ring systems has
somewhat surprisingly received little attention, apart
from investigations on tetrabenzoporphyrins.7 Although
tetranaphthoporphyrin 7 has been reported11 and several
other symmetrical systems have been noted,12 there are
presently few examples of asymmetrical porphyrins with
fused aromatic rings in the literature.13-18 In some cases,
(15) Tome´, A. C.; Lacerdo, P. S. S.; Neves, M. G. P. M. S.; Cavaleiro,
J . A. S. Chem. Commun. 1997, 1199. Alonso, C. M. A.; Neves, M. G. P.
M. S.; Silva, A. M. S.; Cavaleiro, J . A. S.; Hombrecher, H. K.
Tetrahedron Lett. 1997, 38, 2757.
(16) Lash, T. D. Energy Fuels 1993, 7, 166. See also: Lash, T. D. In
Advances in Nitrogen Heterocycles, Vol. 1; Moody, C. J ., Ed.; J AI
Press: 1995, pp 19-69.
(17) (a) Lash, T. D.; Denny, C. P. Tetrahedron 1995, 51, 59. (b) Lash,
T. D.; Wijesinghe, C.; Osuma, A. T.; Patel, J . R. Tetrahedron Lett. 1997,
38, 2031.
(18) Lash, T. D.; Roper, T. J . Tetrahedron Lett. 1994, 35, 7715.
(19) Preliminary communication: Lash, T. D.; Novak, B. H. Tetra-
hedron Lett. 1995, 36, 4381.
(9) Barrett, P. A.; Linstead, R. P.; Rundall, F. G.; Tuey, G. A. P. J .
Chem. Soc. 1940, 1079. J ackson, A. H. In The Porphyrins; Dolphin,
D., Ed.; Academic Press: New York, 1978; Vol. 1, pp 365-388.
(10) Blackburn, E. V.; Timmons, C. J . J . Chem. Soc. (C) 1970, 175.
Snow, A. W.; Price, T. R. Synth. Metals 1984, 9, 329.
(11) Rein, M.; Hanack, M. Chem. Ber. 1988, 121, 1601.
(12) Kobayashi, N.; Nevin, W. A.; Mizunuma, S.; Awaji, H.; Yamagu-
chi, M. Chem. Phys. Lett. 1993, 205, 51.
(13) Mono- and dibenzoporphyrins: (a) Clezy, P. S.; Fookes, C. J .
R.; Mirza, A. H. Aust. J . Chem. 1977, 30, 1337. (b) Clezy, P. S.; Mirza,
A. H. Aust. J . Chem. 1982, 35, 197. (c) Clezy, P. S.; Leung, C. W. F.
Aust. J . Chem. 1993, 46, 1705. (d) Nguyen, L. T.; Senge, M. O.; Smith,
K. M. J . Org. Chem. 1996, 61, 998. (e) Bonnett, R.; McManus, K. A. J .
Chem. Soc., Perkin Trans. 1 1996, 2461. See also ref 16.
(20) Results presented, in part, at the 207th National ACS Meeting,
San Diego, CA, March 1994 (Abstract: Lash, T. D.; Novak, B. H.; Lin,
Y. Book of Abstracts, ORGN 154); 27th Great Lakes/26th Central J oint
Regional ACS Meeting, Ann Arbor, Michigan, J une 1994 (Abstract:
Novak, B. H.; Lash, T. D. Program and Abstracts, Paper No. 419);
208th National ACS Meeting, Washington, DC, August 1994 (Novak,
B. H.; Lash, T. D. Book of Abstracts, ORGN 222 and Lash, T. D.; Novak,
B. H.; Roper, T. J ., Symposium on Porphyrin Geochemistry, Book of
Abstracts, GEOC 12). A popularized account of these studies also
appeared in the Sept 26, 1994 issue of Chem. Eng. News: Freemantle,
M. Porphyrin Syntheses have Geochemical and Environmental Ap-
plications. Chem. Eng. 1994, 72 (39), 25-27.
(14) (a) Crossley, M. J .; Burn, P. L. J . Chem Soc., Chem. Commun.
1991, 1569. (b) Crossley, M. J .; Burn, P. L.; Langford, S. J .; Prashar,
J . K. J . Chem. Soc., Chem. Commun. 1995, 1921. (c) Crossley, M. J .;
Prashar, J . K. Tetrahedron Lett. 1997, 38, 6751.
(21) Paine, J . B., III.; Dolphin, D. J . Org. Chem. 1985, 50, 5598.
(22) Barton, D. H. R.; Zard, S. Z. J . Chem. Soc., Chem. Commun.
1985, 1098. Barton, D. H. R.; Kervagoret, J .; Zard, S. Z. Tetrahedron
1990, 46, 7587.

4000 J . Org. Chem., Vol. 63, No. 12, 1998
Novak and Lash
Sch em e 1
isocyanate moiety and elimination of nitrous acid. Hence,
the nitro group serves two functions: (1) activation of
the carbon-carbon double bond toward nucleophilic
attack; and (2) to facilitate the formation of the aromatic
pyrrole nucleus by loss of nitrite anion. Although one
would not expect this type of chemistry to occur for
nitrobenzene, we speculated that 9-nitrophenanthrene
might have sufficient nitroalkene character to allow the
“Barton-Zard” chemistry to occur.25-27 Nitration of
phenanthrene with nitric acid-acetic anhydride leads to
the formation of all five possible nitrophenanthrene
isomers, but careful chromatography on alumina followed
by recrystallization from ethanol affords the required
isomer 12.28 Initially, 12 was condensed with ethyl
isocyanoacetate (13a ) in the presence of DBU in isopropyl
alcohol and THF at room temperature. Condensation
occurred smoothly to generate the required phenan-
thro[9,10-c]pyrrole system 14 in excellent yields, confirm-
ing our initial speculations.25 However, a substantial
amount of transesterification took place under these
conditions to give a mixture of 14a and 14b. This
transesterification must take place prior to pyrrole
formation as ethyl ester 14a does not react with 2-pro-
panol under these conditions. Not surprisingly, if metha-
nol is used as a cosolvent in this chemistry the methyl
ester 14c is the only product isolated. When the reaction
was carried out in THF alone, the required ethyl ester
was isolated in 78% yield. tert-Butyl isocyanoacetate
(13b) similarly condensed with 12 to give the tert-butyl
ester 14d in 61-65% yield, although benzyl isocyanoac-
etate (13c)24 afforded relatively poor yields of pyrrolic
products under these conditions. This minor problem
was easily overcome by reacting 12 with excess 13c (1.2
equiv) in refluxing THF, and benzyl phenanthro[9,10-
c]pyrrole-2-carboxylate was isolated in 87% yield after
recrystallization from carbon tetrachloride.
F igu r e 1. Partial 300 MHz proton NMR spectra of (A)
phenanthropyrrole 14e and (B) dipyrrylmethane 17c.
Sch em e 2
(23) (a) Ono, N.; Kawamura, H.; Maruyama, K. Bull. Chem. Soc.
J pn. 1989, 62, 3386. (b) Sessler, J . L.; Mozaffari, A.; J ohnson, M. R.
Org. Synth. 1991, 70, 68. (c) Bauder, C.; Ocampo, R.; Callot, H. J .
Tetrahedron 1992, 48, 5135. (d) Medforth, C. J .; Senge, M. O.; Smith,
K. M.; Sparks, L. D.; Shelnutt, J . A. J . Am. Chem. Soc. 1992, 114,
9859. (e) Drinan, M. A.; Lash, T. D. J . Heterocycl. Chem. 1994, 31,
255. (f) Tang, J .; Verkade, J . G. J . Org. Chem. 1994, 59, 7793. (g)
Arnold, D. P.; Burgess-Dean, L.; Hubbard, J .; Rahman, M. A. Aust. J .
Chem. 1994, 47, 969. (h) Haake, G.; Struve, D.; Montforts, F.-P.
Tetrahedron Lett. 1994, 35, 9703. (i) Burns, D. H.; J abara, C. S.;
Burden, M. W. Synth. Commun. 1995, 25, 379. (j) Bag, N.; Chern, S.-
S.; Peng, S.-M.; Chang, C. K. Tetrahedron Lett. 1995, 36, 6409. (k)
Dumoulin, H.; Rault, S.; Robba, M. J . Heterocycl. Chem. 1996, 33, 255.
(l) Adamczyk, M.; Reddy, R. E. Tetrahedron 1996, 52, 14689.
(24) Lash, T. D.; Bellettini, J . R.; Bastian, J . A.; Couch, K. B.
Synthesis 1994, 170.
The proton NMR spectra for 14 were insightful, show-
ing the majority of the phenanthrene protons between
7.5 and 8.6 ppm (Figure 1A). However, the proton
overlying the carbonyl moiety at position 11 was further
deshielded to 9.85 ppm by its proximity to the secondary
π-system, and this observation is useful in the spectro-
scopic assignment of related structures. The pyrrole CH
gave a doublet (J ) 2.8 Hz) at 7.87 ppm, while the NH
appeared as a characteristically broad resonance near 10
ppm. The EI MS for these tetracycles showed primary
fragmentation by loss of ROH, and this presumably leads
to the formation of the ketene radical cation 15 (Scheme
3).
(25) Lash, T. D.; Novak, B. H.; Lin, Y. Tetrahedron Lett. 1994, 35,
2493.
(26) After our initial results were reported,25 independent studies
on the application of nitroarenes to Barton-Zard pyrrole syntheses
were noted: Ono, N.; Hironaga, H.; Ono, K.; Kaneko, S.; Murashima,
T.; Ueda, T.; Tsukamura, C.; Ogawa, T. J . Chem. Soc., Perkin Trans.
1 1996, 417. Murashima, T.; Tamai, R.; Fujita, K.; Uno, H.; Ono, N.
Tetrahedron Lett. 1996, 37, 8391.
The synthesis of phenanthroporphyrins could be ac-
complished in principle by using several different syn-
thetic strategies, and we elected to carry out our studies
by the tried and trusted MacDonald “2 + 2” condensa-
tion.29 In any case, the construction of the porphyrin
(27) For related studies, see J aquinod, L.; Gros, C.; Olmstead, M.
M.; Antolovich, M.; Smith, K. M. Chem. Commun. 1996, 1475. Pelkey,
E. T.; Chang, L.; Gribble, G. W. Ibid., 1909. Gros, C. P.; J aquinod, L.;
Khoury, R. G.; Olmstead, M. M.; Smith, K. M. J . Porphyrins Phtha-
locyanines 1997, 1, 201.
(28) Schmidt, J .; Heinle, E. Chem. Ber. 1911, 44, 1488. Dewar, M.
J . S.; Warford, E. W. T. J . Chem. Soc. 1956, 3570.
(29) (a) Arsenault, G. P.; Bullock, E.; MacDonald, S. F. J . Am. Chem.
Soc. 1960, 82, 4384. (b) Cavaleiro, J . A. S.; Rocha Gonsalves, A. M.
d’A.; Kenner, G. W.; Smith, K. M. J . Chem. Soc., Perkin Trans. 1 1974,
1771. (c) Lash, T. D.; Catarello, J . J . Tetrahedron 1993, 49, 4159.

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 12, 1998 4001
Sch em e 3
Sch em e 5
Sch em e 4
macrocycle relies upon the relative propensity of the
phenanthropyrrole nucleus to undergo electrophilic sub-
stitution at the R-position. While this is to be expected
on theoretical grounds, this premise was initially tested
by reacting 14a with bromine in acetic acid at room
temperature (Scheme 2). The corresponding R-bromo
derivative 16 was generated in good yield, confirming our
expectations. This chemistry was applied to the synthe-
sis of dipyrrylmethanes 17 (Scheme 4) by condensing the
well-known (acetoxymethyl)pyrroles 18 with phenan-
thropyrroles 14 in the presence of p-toluenesulfonic acid
in acetic acid or Montmorillonite clay in dichloromethane.30
The mild conditions utilized were compatible with the
presence of tert-butyl esters, as well as ethyl and benzyl
ester moieties, and six examples of the dipyrrolic system
17 were prepared in this fashion and fully characterized.
These dipyrroles could be isolated as white solids, but
these generally turned pink on exposure to air. However,
these compounds are otherwise quite stable and further
decomposition does not appear to take place even after
several years. In the proton NMR spectra for 17, the
bridging methylene unit was observed at 4.5-4.6 ppm
compared to values near 3.9 ppm for dipyrrylmethanes
lacking the fused phenanthrene moiety. This downfield
shift is consistent with the deshielding anisotropy of the
proximal polycyclic π-system (Figure 1B).
Monophenanthroporphyrins 19 and 20 were prepared
using the MacDonald “2 + 2” synthesis from dipyrryl-
methanes 17a and 17b (Scheme 5). The bis-tert-butyl
ester 17a was treated with TFA at room temperature for
15 min, and the resulting mixture diluted with dichlo-
romethane, washed with aqueous sodium bicarbonate
solution, dried, and evaporated to give the deprotected
diunsubstituted dipyrrylmethane 21. Condensation with
diformyldipyrrylmethane 22a in the presence of p-tolu-
enesulfonic acid in methanol-dichloromethane, followed
by addition of zinc acetate and air oxidation of the
porphodimethene intermediate 23, afforded the extended
porphyrin structure 19 in modest yields. The low yields
(12%) obtained in this chemistry were disappointing, but
we felt that this might have been due to the instability
of the diunsubstituted dipyrrylmethane 21 and the
extensive handling required to isolate this intermediary
species. To overcome this perceived problem, the related
dicarboxylic acid 24 was prepared by hydrogenolysis of
the dibenzyl ester 17b over 10% palladium-charcoal. The
dicarboxylic acid would be expected to undergo in situ
decarboxylation to generate 21 under the conditions
utilized to carry out the porphyrin condensation. In the
event, reaction of 24 with dialdehyde 22a afforded
phenanthro[9,10-b]porphyrin 19 in 29% yield. Reaction
of 24 with the dibutyldipyrrole 22b similarly gave
porphyrin 20, although the yield was only 18% in this
case. However, this was raised to over 30% yield when
more dilute conditions were used for the “2 + 2” conden-
sation.
The structures of 19 and 20 were confirmed by NMR
spectroscopy and mass spectrometry. The proton NMR
spectra were consistent with the expected aromatic
structures and exhibited the usual powerful porphyrin
diatropic ring current. For instance, the methyl substit-
uents were shifted downfield to 3.5-3.6 ppm, values that
are in the typical range for â-alkyl-substituted porphy-
(30) J ackson, A. H.; Pandey, R. K.; Rao, K. R. N.; Roberts, E.
Tetrahedron Lett. 1985, 26, 793.

4002 J . Org. Chem., Vol. 63, No. 12, 1998
Novak and Lash
Sch em e 6
tautomers (Scheme 6). These structures represent dif-
ferent chromophores and may have quite distinct absorp-
tion spectra. The observed UV-vis data, according to the
Franck-Condon principle, will correspond to a superim-
position of the two sets of absorptions, although it is
certainly possible that one tautomer will predominate.
In tautomer B, the 18 π electron delocalization pathway
within the porphyrin macrocycle bypasses the phenan-
threne nucleus altogether, and the dominance of this
species might explain the limited shifts observed. For
the free bases of these porphyrins, the phenanthrene unit
behaves more like an auxochrome than part of a truly
conjugated system, and these considerations may allow
the data to be rationalized. In the dication, tautomer-
ization is no longer a factor, and the phenanthrene
subunit may exert a larger effect in this case. However,
the crowded macrocyclic cavity is likely to induce the
system to attain a less planar conformation, and this may
also be a factor.
F igu r e 2. Partial 300 MHz NMR spectrum of phenanthro-
porphyrin 19.
To further investigate this phenomenon, the corre-
sponding nickel(II), copper(II), and zinc complexes (26a -
c) were prepared. These all showed single Soret bands
at 412, 414, and 418 nm, respectively. The longer
wavelength region was two-banded, as is typically ob-
served for metalloporphyrins, where the higher wave-
lenth or R-band was more intense than the lower wave-
length â-band. The relative intensity of the â absorption
increased from Ni to Zn, and both bands underwent
bathochromic shifts with increasing atomic number for
the coordinating transition metal cation. All of these
trends are seen for simple octaalkylporphyrin chelates
such as for octaethylporphyrin (OEP).31 The red-shifting
influence of the phenanthrene subunit on the λmax values
for these metal complexes were on the order of 11-27
nm compared to the OEP chelates. The relatively small
shifts involved are comparible for the free base porphy-
rins (19 vs OEP), and this demonstrates that the elec-
tronic structure of the metal chelates is similar to the
parent structures. No tautomeric processes can be
operating for 26a -c and it remains unclear why the
π-system of the phenanthrene exerts such a small effect.
Further speculation will have to await detailed theoreti-
cal analyses.
F igu r e 3. UV-vis spectrum of phenanthroporphyrin 19 in
dichloromethane.
rins. In addition, the internal NHs resonated at a typical
value of -4.0 ppm, while the external meso-protons
appeared near 9.8 (for 2H) and 10.74 (for 2H) ppm
(Figure 2). The downfield 2H resonance corresponded
to the meso-protons adjacent to the phenanthrene sub-
unit, and the additional deshielding is undoubtedly due
in part to the proximity of these methine protons to the
phenanthrene π-system, although steric interactions may
also be a factor. By the same token, the two phenan-
threne protons nearest to the porphyrin macrocycle were
considerably deshielded and were observed near 9.8-9.9
ppm. The UV-vis spectra for 19 and 20 closely resembled
the spectra obtained for naphtho[1,2-b]porphyrin 9, and
the bathochromic shifts for the major λmax values were
all less than 4 nm (Figure 3). For 19 and 20, a strong
Soret band appeared at 417 nm, compared to 415 nm for
9, and the Q-band region was unexceptional. The most
red shifted band (Q1) was relatively weak and appeared
at 634 nm, compared to a value of 630 nm in the
naphthoporphyrin case. These results suggest that the
porphyrin chromophore virtually ignores the presence of
the phenanthrene ring system and the π-interactions
clearly do not follow the simplistic trends that we had
originally anticipated. In the presence of TFA, dications
25 were generated and these showed split Soret band at
403 and 420 nm. This spectrum differs considerably from
the spectra for octaalkylporphyrin dications, which ex-
hibit a single Soret absorption. One factor that is difficult
to assess in these studies is that phenanthroporphyrins
19 and 20 most likely exist as two rapidly interconverting
Although the phenanthroporphyrin chromophore in 19
or 20 showed no unusual electronic absorption properties,
the synthesis of diphenanthrene appended structures was
considered to be a worthwhile goal. In addition to
discovering more about the electronic properties of por-
phyrins with fused aromatic rings, the well-defined
nature of these extended porphyrin structures may have
relevence to the development of nanomolecular based
(31) Porphyrins and Metalloporphyrins; Smith, K. M., Ed., Elsevi-
er: New York, 1975; pp 871-889.

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 12, 1998 4003
Sch em e 7
Sch em e 8
systems such as molecular wires.14 The successful syn-
thesis of 19 and 20 using the MacDonald condensation
suggested that the same strategy could be utilized in the
synthesis of diphenanthroporphyrins. The opp-diphenan-
throporphyrin system 27 can be prepared by the self-
condensation of a suitably substituted dipyrrylmethane
monoaldehyde (Scheme 7). The mixed ester dipyrroles
17d and 17f were treated with trifluoroacetic acid to
cleave the tert-butyl ester protective groups and subse-
quent formylation with Clezy’s variant on the Vilsmeier
reaction (PhCOCl-DMF)32 gave the corresponding alde-
hydes 28. Hydrogenolysis over 10% palladium on acti-
vated carbon then gave the related carboxylic acids 29.
Formyldipyrrylmethane 29a was treated with p-toluene-
sulfonic acid in methanol-dichloromethane and this
induced the decarboxylation of the pyrrolecarboxylic acid,
followed by a head-to-tail self-condensation of two dipyr-
rolic units. Following addition of zinc acetate, air oxida-
tion, and workup, the required porphyrin 27a with two
oppositely fused fused phenanthrene rings was isolated
in good yields. Unfortunately, this compound was very
difficult to work with due to its virtual insolubility in
most organic solvents. Self-condensation of 29b gave the
related opp-diphenanthroporphyrin 27b, and this com-
pound was slightly more soluble in chloroform giving
green solutions. Transesterification with n-butyl alcohol
gave the corresponding dibutyl ester 27c, and the longer
side chains is this structure gave rise to increased
solubility. The adj-diphenanthroporphyrin system 30
was approached in a similar fashion (Scheme 8). Con-
densation of phenanthropyrroles 14a , 14c, or 14e with
dimethoxymethane in the presence of p-toluenesulfonic
acid in acetic acid under a nitrogen atmosphere afforded
the symmetrical dipyrrylmethanes 31 in excellent yields.
These symmetrical dipyrrylmethanes were insufficiently
soluble in CDCl3 for NMR data to be obtained in this
solvent, although 31c had some solubility in d6-DMSO
and 31a and 31b dissolved to a limited extent in d8-THF.
The bridging methylene unit in these structures was
considerably deshielded by the presence of two proximate
phenanthrene ring systems and resonated near 5.5 ppm.
The low solubility of the dibenzyl ester 31c made this
compound unsuitable for deprotection by hydrogenolysis,
F igu r e 4. Electronic spectrum (Soret band excluded) of opp-
diphenanthroporphyrin 27c in chloroform.
and our attentions focused on the saponification of the
diethyl or dimethyl ester counterparts. The ester units
were conveniently cleaved with concomitant decarboxy-
lation by refluxing 31a or 31b with KOH in ethylene
glycol for 25 min with strict exclusion of oxygen. The
deprotected dipyrrole 32 was immediately condensed
with dialdehyde 22b under standard conditions to give
the targeted adj-diphenanthroporphyrin. Initially, poor
yields of 30 were observed, but under more dilute
conditions reasonable yields (18%) were obtainable. This
porphyrin was insufficiently soluble in chloroform to
obtain an NMR spectrum for the free base, although the
data for the corresponding dication could be obtained in
the presence of trifluoroacetic acid. The symmetry of this
compound was confirmed by the proton NMR of the
dication, and three separate resonances were observed
for the meso-protons at 10.4 (1H), 11.4 (2H), and 12.3 (1H)
ppm. Not surprisingly, the methine bridge proton flanked
by two phenanthrene ring systems is further deshielded
to below 12 ppm.
The UV-vis spectra for the free bases of opp-diphenan-
throporphyrins 27b and 27c showed a Soret band at 428
nm and three Q-bands at 568, 591, and 645 nm, although
the highest wavelength absorption was very weak (Figure
4). Poor solubility in the case of 27b gave rise to slightly
turbid green solutions in chloroform and this made molar
(32) Chong, R.; Clezy, P. S.; Liepa, A. J .; Nichol, A. W. Austr. J .
Chem. 1969, 22, 229.

4004 J . Org. Chem., Vol. 63, No. 12, 1998
Novak and Lash
the tetraphenanthroporphyrin 10 (Scheme 9).33 Reduc-
tion of ethyl ester 14a with lithium aluminum hydride
in THF at 0 °C afforded the unstable carbinol 35,34 and
this was immediately cyclotetramerized to give the
tetraphenanthrene-fused porphyrin 10. Initially, we
attempted to carry the chemistry out in refluxing pyri-
dine-acetic acid,35 but no detectable porphyrin products
were formed under these conditions. However, by adapt-
ing the Lindsey conditions for tetraarylporphyrin syn-
thesis, this moderately crowded porphyrin structure was
attainable. Treatment of freshly prepared 35 with boron
trifluoride etherate in chloroform generated the porphy-
rinogen 36, and subsequent oxidation with DDQ afforded
the symmetrical porphyrin system 10. Following recrys-
tallization from chloroform-methanol, this novel hepta-
decacycle was isolated as a greenish-black powder in 13%
yield. It is notable that much poorer results were
obtained when dichloromethane was used as a reaction
solvent. This difference may be due to the presence of
approximately 0.8% ethanol in the commercially avail-
able chloroform used for our studies as this can be a
factor in tetraarylporphyrin formation.36 Tetraphenan-
throporphyrin 10 showed very little solubility in organic
solvents, and UV-vis data could only be obtained for
turbid partially dissolved and presumably aggregated
material (λmax (benzene) 430, 650, 704 nm). In the
Ch a r t 2. Din a p h th op or p h yr in s
absorptivity measurements difficult (sloping baselines
were observed in this case), although dibutyl ester 27c
afforded clear green solutions and gave superior UV-vis
data. The adj-diphenanthrene system 30 showed slightly
longer wavelength shifts with a Soret band at 433 nm
and four Q-bands at 536, 569, 594, and 652 nm. Both
systems showed some significant similarities to the
analogous opp- (33) and adj-dinaphthoporphyrins (34)
(Chart 2),18 and it is interesting to note that the adjacent
ring fused structures gave the longer wavelength absorp-
tions for both series. For 27b and 27c, Q-bands III and
IV appear to have coalesced, bands II and III are
separated by only 23 nm and band I has almost disap-
peared. While the shifts for the dinaphthoporphyrin
counterpart 33 are less extreme (λmax 425 (Soret), 530
(weak, Q4), 564 (Q3), 584 (Q2) and 641 (Q1) nm), and the
Q1 band is stronger, the same general features are
present. The UV-vis spectra for adj-dinaphthoporphyrin
34 (λmax 424 (Soret), 533 (Q4), 566 (Q3), 585 (Q2), and 644
(Q1) nm) and the related diphenanthroporphyrin 30 also
show many similarities and exhibit a more typical four-
banded pattern of Q absorptions. The dication of 27a
and 27b showed a split Soret band at 436 and 458 nm,
together with weaker absorptions at 581 and 638 nm,
while the adj-diphenanthrene system 30 gave a single
Soret absorption at 448 nm and longer wavelength bands
at 584 and 632 nm. The nickel(II), copper(II), and zinc
chelates of 30 were prepared, together with the zinc
chelate of opp-diphenanthroporphyrin 27c (only one
metal complex was prepared in this case due to the
limited quantities of material available). The nickel(II),
copper(II), and zinc complexes of 30 showed the same
trends previously noted for the monophenanthroporphy-
rin system 26, although the molar extinction coefficients
for the copper chelate could not be obtained due to its
extremely poor solubility characteristics and the zinc
complex only completely dissolved in the presence of trace
pyrrolidine. The zinc chelate gave a relatively sharp
Soret band at an anomolously high wavelength value of
453 nm (compared to 429 and 432 nm for Ni(II) and
Cu(II) complexes, respectively), and the Q-bands were
similarly shifted to unusually high values (Figure 5; λmax
573 and 614 nm). The opp-diphenanthroporphyrin zinc
chelate gave a similar result (Figure 5), although the
bathochromic shifts were not as large in this case (λmax
440 (Soret), 565, 614 nm). In this respect, the results
parallel those for the free bases 27 and 30, which also
showed the larger red shifts in the adjacent ring fusion
case. Clearly, distinct trends are emerging from these
studies and further data may allow a deeper understand-
ing of these results to be forthcoming.
presence of 1% TFA, the system was diprotonated to give
2+
deep green solutions of the corresponding dication 10H2
.
This species showed significant bathochromic shifts, with
the Soret band appearing at 482 nm together with two
weaker absorptions at 615 and 668 nm. These bands
have been considerably shifted compared to the dications
for mono- and diphenanthroporphyrins discussed above,
although when one considers the degree of ring fusion
these effects are surprisingly small. The proton NMR
2+
spectrum of 10H2 was consistent with a symmetrical
structure, and the proton ring current was manifested
in the observed chemical shifts. The meso-protons ap-
peared downfield as a 4H singlet near 12.0 ppm, the
deshielding being due in part to the proximity of two
phenanthrene subunits. The high level of symmetry in
10H22+ was particularly well illustrated in its carbon-13
NMR spectrum where the 68 carbon atoms in this
structure gave rise to only nine resonances.
Con clu sion s
The “Barton-Zard” reaction of 9-nitrophenanthrene
with esters of isocyanoacetic acid provides a convenient
route to phenanthro[9,10-c]pyrroles 14 and these tetra-
cyclic structures are easily converted into porphyrins
with one, two, or four fused phenanthrene rings. The
ring fusion induces limited bathochromic shifts in the
electronic spectra of phenanthroporphyrins and their
(33) Lash, T. D.; Novak, B. H. Angew. Chem., Int. Ed. Engl. 1995,
34, 683.
(34) (a) Ono, N.; Kawamura, H.; Bougauchi, M.; Maruyama, K.
Tetrahedron 1990, 46, 7483. (b) Lash, T. D.; Balasubramaniam, R. P.;
Catarello, J . J .; J ohnson, M. C.; May, D. A., J r.; Bladel, K. A.; Feeley,
J . M.; Hoehner, M. C.; Marron, T. G.; Nguyen, T. H.; Perun, T. J ., J r.;
Quizon, D. M.; Shiner, C. M.; Watson, A. Energy Fuels 1990, 4, 668.
(c) May, D. A., J r.; Lash, T. D. J . Org. Chem. 1992, 57, 4820. (d) Chen,
S.; Lash, T. D. J . Heterocycl. Chem. 1997, 34, 273.
(35) Treibs, A.; Haberle, N. Liebigs Ann. Chem. 1968, 450, 164.
(36) Lindsey, J . S.; Schreiman, I. C.; Hsu, H. C.; Kearney, P. C.;
Marguerettaz, A. M. J . Org. Chem. 1987, 52, 827. Lindsey, J . S.;
Wagner, R. W. J . Org. Chem. 1989, 54, 828. Lindsey, J . S.; MacCrum,
K. A.; Tyhonas, J . S.; Chuang, Y.-Y. J . Org. Chem. 1994, 59, 9, 579.
These studies had demonstrated that porphyrins with
two fused phenanthrene rings were easily synthesized
and so we turned our attentions to the preparation of

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 12, 1998 4005
F igu r e 5. Electronic spectra (Soret bands excluded) of the zinc complexes of (A) monophenanthroporphyrin 19 in chloroform; (B)
opp-diphenanthroporphyrin 27c in chloroform; (C) adj-diphenanthroporphyrin 30 in trace pyrrolidine-chloroform.
mL) and then dried over sodium sulfate. The solvent was
evaporated under reduced pressure and the product purified
by distillation to give the N-formylglycinate (94.7 g; 92%) as a
colorless liquid, bp 103-105 °C at 0.1-0.2 mmHg (lit.39 bp 105
°C at 0.15mbar); IR (Nujol mull): ν 3335 (NH str), 1742, 1673
(CdO str) cm-1; 1H NMR (CDCl3): δ 1.47 (9H, s), 3.97 (2H, d,
J ) 5.1 Hz), 6.18 (1H, br s), 8.23 (1H, s).
Sch em e 9
ter t-Bu tyl Isocya n oa ceta te (13b). A stirred solution of
tert-butyl N-formylglycinate (60.60 g) and triethylamine (92.25
g) in dichloromethane (381 mL) were placed in a 3 L three-
necked round-bottomed flask equipped with an addition fun-
nel, thermometer, and drying tube, and the mixture was cooled
to between -2 and 0 °C in an ice-salt bath. Freshly distilled
phosphoryl chloride (58.29 g) was added dropwise, while the
temperature was maintained at 0 °C. Once the addition was
complete, the reddish-brown mixture was stirred at 0 °C for
an additional 1 h. The ice-salt bath was replaced with an
ice-water bath, and sodium carbonate solution (76.2 g in 305
mL water) was added at a sufficient rate to maintain the
temperature of the mixture between 25 and 30 °C. The
biphasic mixture was stirred for 30 min, after which water
was added until the volume of the aqueous layer was brought
up to 765 mL. The aqueous layer was separated and extracted
with dichloromethane (2 × 200 mL). The combined organic
extracts were washed with brine and dried over potassium
carbonate. The solvent was evaporated under reduced pres-
sure and the remaining brown oil distilled under reduce
pressure to afford the isocyanoacetate (42.50 g; 80%) as a pale
yellow liquid, bp 85.5-95 °C at 20 mmHg or 44-49 °C at 0.10
mmHg (lit. bp40 57 °C at 0.5 Torr); IR (Nujol mull): 162 (st,
metal chelates, but these effects are smaller than might
have been expected.37 Nonetheless, some interesting
trends are emerging from these studies and these could
lead to applications (by analogy to the phthalocyanines)
in the future.
sh, CtN), 1754 (st, sh, CdO) cm-1 1H NMR (CDCl3): 1.50
;
(9H, s), 4.13 (2H, s).
9-Nitr op h en a n th r en e (12). Nitric acid (6 mL) was added
dropwise (exothermic reaction) to a stirred acetic anhydride
(12 mL). The resulting mixture was gradually added to a
solution of phenanthrene (8.00 g) in glacial acetic acid (16 mL),
moderating the rate of addition to avoid an overly vigorous
reaction. The mixture was heated on a boiling water bath for
1-2 h and then poured into 500 mL of ice-water. The water
was decanted off from the resulting yellow gum, and the
residue was dissolved in chloroform (75 mL). The ice-water
solution was extracted with 50 mL of chloroform, and the
combined organic solutions were washed sequentially with
water (25 mL), 5% aqueous sodium bicarbonate solution (25
mL), and water (25 mL). The organic layer was dried over
sodium sulfate, and the solvent was evaporated under reduced
pressure. The residue was taken up in a small amount of
toluene and loaded on a column (41 mm internal diameter ×
250 mm) of grade 3 alumina and eluted with hexanes. After
the yellow nitrophenanthrene fraction started to elute, ap-
proximately 2.0 L of hexanes was collected. Evaporation of
the solvent under reduced pressure, followed by recrystalli-
Exp er im en ta l Section 38
tert-Butyl chloroacetate was obtained from Fluka Chemie
AG; all other chemicals were purchased from Aldrich Chemical
Co. and were not further purified unless otherwise indicated.
ter t-Bu tyl N-F or m ylglycin a te. A mixture of formamide
(200 mL) and sodium methoxide in methanol (prepared by
reacting sodium (17.5 g) with 137 mL of methanol) was stirred
in a 1 L round-bottomed flask at room temperature for 5 min.
The flask was placed on a rotary evaporator for 2 h and then
further evacuated overnight using a vacuum pump. The
resulting oil was heated to 52 °C on a water bath. tert-Butyl
chloroacetate (104.0 g) was added slowly, maintaining the
reaction temperature at 55 °C throughout. After being stirred
4-6 h at room temperature, the mixture was poured into a
cold sodium carbonate solution (60.0 g in 600 mL of water)
and the heterogeneous mixture stirred at room-temperature
overnight. If any solid formed, it was filtered off. The filtrate
was extracted with dichloromethane (6 × 50 mL), and the
combined organic extracts were washed with brine (2 × 30
(37) (a) Lin, Y.; Lash, T. D. Tetrahedron Lett. 1995, 36, 9441. (b)
Chandrasekar, P.; Lash, T. D. Tetrahedron Lett. 1996, 37, 4873. (c)
Lash, T. D.; Chandrasekar, P. J . Am. Chem. Soc. 1996, 118, 8767.
(38) For general experimental procedures, see ref 1.
(39) Medura, V.; Sawlewicz, P.; Vogt, R. Synth. Comm. 1989, 19,
1497.
(40) Ugi, I.; Betz, W.; Fetzer, U.; Offermann, K. Chem. Ber. 1961,
94, 2814.

4006 J . Org. Chem., Vol. 63, No. 12, 1998
Novak and Lash
zation from 95% ethanol, gave the desired nitrophenanthrene
isomer (2.24 g; 22%) as yellow crystals, mp 117 °C (lit. mp28
116-117 °C). 1H NMR (CDCl3): δ 7.68-7.86 (4H, m), 8.02
(1H, d, J ) 7.9 Hz), 8.48 (1H, s), 8.49-8.52 (1H, m), 8.71 (1H,
d, J ) 7.9 Hz), 8.76-8.79 (1H, m).
Recrystallization from carbon tetrachloride gave the methyl
ester 14c (1.489 g; 54%) as a white powder, mp 193-194 °C;
IR (Nujol mull): ν 3431 (NH str), 1698 (CdO str), 760
(phenanthrene-H out-of-plane bending) cm-1
;
1H NMR
(CDCl3): δ 4.00 (3H, s), 7.50-7.66 (4H, m), 7.76 (1H, d, J )
3.3 Hz), 8.05-8.08 (1H, m), 8.51-8.59 (2H, m), 9.77-9.81 (1H,
Eth yl P h en a n th r o[9,10-c]p yr r ole-1-ca r boxyla te (14a ).
DBU (1.596 g) was added dropwise to a solution of ethyl
isocyanoacetate41 (1.185 g) and 9-nitrophenanthrene (2.339 g)
in THF (20 mL), and the resulting mixture was stirred at
room-temperature overnight. The solution was diluted with
chloroform, washed with water, and dried over sodium sulfate.
The solvent was evaporated under reduced pressure and the
residue recrystallized from toluene to give the pyrrole (2.376
g; 78%) as yellow crystals, mp 177-178 °C; IR (Nujol mull):
1
m), 9.90 (1H, br s); H NMR (d8-THF): δ 3.94 (3H, s), 7.44-
7.54 (4H, m), 7.96 (1H, d, J ) 3.3 Hz), 8.17-8.20 (1H, m),
8.54-8.62 (2H, m), 9.89-9.93 (1H, m), 11.97 (1H, br s); 1H
NMR (d6-DMSO-CDCl3): δ 3.95 (3H, s), 7.4-7.54 (4H, m),
7.84 (1H, d, J ) 3.6 Hz), 8.06-8.09 (1H, m), 8.45-8.52 (2H,
m), 9.72-9.76 (1H, m), 12.17 (1H, br s); 13C NMR
(d6-DMSO-CDCl3): δ 50.5, 114.6, 115.6, 121.2, 122.2, 122.3,
122.5, 122.9, 124.8, 125.8, 126.0, 126.5, 127.0 (2), 127.4, 127.5,
129.4, 160.7; EI MS: m/z (% rel abund) 275 (59; [M+]), 243
(100; [M - MeOH]+). Anal. Calcd for C18H13NO2: C, 78.53;
H, 4.76; N, 5.09. Found: C, 78.36; H, 4.84; N, 5.09.
ν 3297 (NH str), 1659 (CdO str) cm-1 1H NMR (CDCl3): δ
;
1.47 (3H, t, J ) 7.2 Hz), 4.48 (2H, q, J ) 7.2 Hz), 7.58 (2H,
m), 7.67 (2H, m), 7.86 (1H, d, J ) 3 Hz), 8.15 (1H, m), 8.60
(2H, m), 9.85 (1H, m), 10.0 (1H, br s); 13C NMR (CDCl3): δ
14.6, 60.7, 114.9, 116.1, 122.8, 122.9, 123.1, 123.5, 124.0, 125.8,
126.8, 127.0, 127.1, 127.5, 128.4, 128.9, 130.5, 160.6; EI MS:
m/z (% rel abund) 289 (52; [M+]), 243 (100; [M - EtOH]+). Anal.
Calcd for C19H15NO2: C, 78.87; H, 5.22; N, 4.84. Found: C,
79.18; H, 5.34; N, 4.85.
Eth yl 3-Br om op h en a n th r o[9,10-c]p yr r ole-1-ca r boxy-
la te (16). Bromine (0.14 g) was added dropwise to a stirred
solution of 14a (0.25 g) in acetic acid, and the resulting solution
stirred at room temperature for 10 min. The solution was
diluted with chloroform and washed with water, 5% sodium
bicarbonate solution and water. The solution was dried over
sodium sulfate, filtered, and evaporated under reduced pres-
sure. The residue was recrystallized from chloroform-hexanes
to give the 3-bromo derivative (0.26 g; 81%) as pale yellow
microneedles, mp 163 °C, dec (sample starts to darken at 120
ter t-Bu t yl P h en a n t h r o[9,10-c]p yr r ole-1-ca r b oxyla t e
(14d ). Over a period of 5 min, DBU (1.796 g) was added
dropwise to a stirred mixture of 9-nitrophenanthrene (1.32 g)
and tert-butyl isocyanoacetate (0.832 g) in THF (15 mL) and
2-propanol (15 mL). The solution was stirred overnight at
room temperature, diluted with chloroform, washed with 25
mL of water, and dried over sodium sulfate. The solvent was
evaporated and the residual oil taken up in a small amount
of hexanes and loaded onto a silica gel eluting with hexanes.
After unreacted 9-nitrophenanthrene had eluted from the
column, the solvent was switched to toluene, and a major
product fraction was collected. Recrystallization from carbon
tetrachloride gave the phenanthropyrrole (1.143 g; 61%) as
pale yellow crystals, mp 178 °C. An analytical sample was
obtained by recrystallization from toluene as yellow crystals,
mp 176 °C (softens at 170 °C). IR (Nujol mull): ν 3297 (NH
°C); IR (Nujol mull): ν 3220 (NH str), 1656 (CdO str) cm-1
;
1H NMR (CDCl3): δ 1.49 (3H, t, J ) 7.2 Hz), 4.49 (2H, q, J )
7.2 Hz), 7.51-7.62 (4H, m), 8.52-8.56 (2H, m), 8.98-9.02 (1H,
m), 9.73-9.77 (1H, m), 9.81 (1H, br s); 13C NMR (CDCl3): δ
14.7, 61.3, 98.6, 116.8, 119.2, 122.7, 123.4, 123.7, 126.0, 126.6,
127.0, 127.0, 127.2, 127.4, 127.7, 128.6, 129.9, 130.9, 160.1.
Anal. Calcd for C19H14BrNO2: C, 61.97; H, 3.83; N, 3.80.
Found: C, 61.24; H, 3.91; N, 3.66.
Ben zyl 3-((5-(Ben zyloxyca r bon yl)-3-eth yl-4-m eth yl-2-
p yr r olyl)m et h yl)p h en a n t h r o[9,10-c]p yr r ole-1-ca r b oxy-
la te (17b). Method A: p-Toluenesulfonic acid (13 mg) was
added to a stirred mixture of benzyl phenanthro[9,10-c]pyrrole-
1-carboxylate (14e; 250 mg) and benzyl 5-(acetoxymethyl)-4-
ethyl-3-methylpyrrole-2-carboxylate42 (18a ; 224 mg) in glacial
acetic acid (25 mL). The mixture was stirred at room tem-
perature for 2 h, and the solution was then poured into 250
mL ice/water and allowed to stand for a further 2 h. The
mixture was extracted with chloroform, and the organic layer
was washed with 3 × 25 mL of portions water, 5% sodium
bicarbonate solution (25 mL), and water (25 mL) and dried
over sodium sulfate. The solvent was evaporated under
reduced pressure and the solid residue recrystallized from
carbon tetrachloride to give the dipyrrylmethane (347 mg;
80%) as white crystals, mp 182-183 °C; IR (Nujol mull): ν
1
str), 1659 (CdO str) cm-1; H NMR (CDCl3): δ 1.70 (9H, s),
7.46-7.63 (4H, m), 7.74 (1H, d, J ) 3.3 Hz), 8.05-8.08 (1H,
m), 8.50-8.57 (2H, m), 9.76 (1H, d, J ) 7.8 Hz), 9.86 (1H, br
s); 13C NMR (CDCl3): δ 28.6, 81.8, 114.1, 117.6, 122.9, 123.1,
123.3, 123.5, 125.7, 126.6, 126.9, 127.0, 127.7, 128.6, 128.9,
130.9, 160.3; EI MS: m/z (% rel abund) 317 (21; [M+]), 261
(50; [M - (CH3)2CdCH2]+), 243 (100; [M - t-BuOH]+). Anal.
Calcd for C21H19NO2: C, 79.47; H, 6.03; N, 4.41. Found: C,
79.33; H, 5.92; N, 4.13.
Ben zyl P h en a n th r o[9,10-c]p yr r ole-1-ca r boxyla te (14e).
Benzyl isocyanoacetate24 (2.395 g) and 9-nitrophenanthrene
(2.730 g) were dissolved in anhydrous THF (30 mL). DBU
(2.235 g) was added dropwise over several minutes, and the
resulting mixture was heated under reflux overnight. The
organic phase was diluted with chloroform, washed with water,
and dried over sodium sulfate. The solvent was removed
under reduced pressure and the residue taken up in a small
amount of toluene and loaded on a silica gel column. The
column was eluted with toluene, and a yellow band was
collected. Recrystallization from carbon tetrachloride gave the
phenanthropyrrole (3.737 g; 87%), as pale yellow crystals, mp
185-186 °C; IR (Nujol mull): ν 3425 (NH str), 1696 (CdO str)
cm-1; 1H NMR (CDCl3): δ 5.44 (2H, s), 7.37-7.59 (9H, m), 7.77
(1H, d, J ) 3.3 Hz), 8.05-8.08 (1H, m), 8.50-8.57 (2H, m),
9.77-9.79 (1H, m), 9.80 (1H, br s); 13C NMR (CDCl3): δ 66.6,
115.3, 115.6, 122.9, 123.2, 123.5, 125.8, 126.9, 127.1, 127.1,
127.4, 127.5, 128.5 (2), 128.8, 128.9, 130.6, 136.0, 160.0; EI
MS: m/z (% rel abund) 351 (68; [M+]), 243 (47; [M - BnOH]+),
91 (100). Anal. Calcd for C24H17NO2‚1/5H2O: C, 81.20; H, 4.94;
N, 3.94. Found: C, 81.20; H, 4.87; N, 3.87.
1
3412, 3301 (2 × NH str), 1710, 1668 (2 × CdO str) cm-1; H
NMR (CDCl3): δ 1.01 (3H, t, J ) 7.5 Hz), 2.31 (3H, s), 2.41
(2H, q, J ) 7.5 Hz), 4.53 (2H, s), 5.22 (2H, s), 5.33 (2H, s),
7.29-7.33 (10H, m), 7.49-7.58 (4H, m), 8.03-8.04 (1H, m),
8.53-8.56 (2H, m), 8.67 (1H, br s), 9.38 (1H, br s), 9.79-9.77
(1H, m); 13C NMR (CDCl3): δ 10.6, 15.2, 17.3, 27.1, 65.7, 66.3,
113.0, 118.0, 118.5, 123.0, 123.4, 123.7, 125.2, 125.5, 126.3,
126.5, 126.7, 127.1, 127.4, 127.7, 128.0 (2), 128.2, 128.3, 128.5,
128.6, 129.5, 130.4, 135.9, 159.9, 161.2; EI MS: m/z (% rel
abund) 606 (23; [M+]), 504 (63), 91 (100). Anal. Calcd for
C
40H34N2O4‚1/2H2O: C, 78.03; H, 5.73; N, 4.55. Found: C,
77.68; H, 5.51; N, 4.46.
Method B: A solution of 14e (100 mg) and 18a (90 mg) in
dichloromethane (10 mL) was stirred vigorously with Mont-
morillonite clay (520 mg) for 16 h. The catalyst was filtered
off and washed with dichloromethane, and the combined
organic solutions were evaporated under reduced pressure.
Recrystallization from carbon tetrachloride gave the dipyrryl-
methane (160 mg; 93%) as pink crystals, mp 180-182 °C.
ter t-Bu tyl 3-((5-(ter t-Bu toxyca r bon yl)-3-eth yl-4-m eth -
yl-2-p yr r olyl)m et h yl)p h en a n t h r o[9,10-c]p yr r ole-1-ca r -
Meth yl P h en an th r o[9,10-c]pyr r ole-1-car boxylate (14c).
The foregoing reaction of 13c (1.962 g) and 12 (2.237 g) was
carried out in refluxing methanol (15 mL)-THF (15 mL).
(42) J ohnson, A. W.; Kay, I. T.; Markham, E.; Price, R.; Shaw, K.
B. J . Chem. Soc. 1959, 3416.
(41) Hartman, G. D.; Weinstock, L. M. Org. Synth. 1979, 59, 183.

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 12, 1998 4007
boxyla te (17a ). The dipyrrylmethane was prepared from tert-
butyl phenanthro[9,10-c]pyrrole-1-carboxylate (14d ; 1.00 g)
and tert-butyl 5-(acetoxymethyl)-4-ethyl-3-methylpyrrole-2-
carboxylate43 (18b; 0.887 g) by method A. The reaction
mixture was poured into ice/water (350 mL) and the resulting
precipitate collected by suction filtration. Recrystallization
from methanol gave the dipyrrylmethane (1.445 g; 85%) as
pink crystals, mp 191-192 °C; IR (Nujol mull): ν 3424 (NH
Ben zyl 3-((5-(ter t-Bu toxyca r bon yl)-3-(2-(m eth oxyca r -
bon yl)eth yl)-4-m eth yl-2-pyr r olyl)m eth yl)ph en an th r o[9,10-
c]p yr r ole-1-ca r b oxyla t e (17f). The dipyrrylmethane was
prepared by method A from 14e (200 mg) and tert-butyl
5-(acetoxymethyl)-4-(2-(methoxycarbonyl)ethyl)-3-methylpyr-
role-2-carboxylate44 (18d ; 193 mg). Recrystallization from 95%
ethanol gave the desired dipyrrylmethane (191 mg; 53%) as
pale pink crystals. Method B afforded the mixed ester species
17f in 80% yield, mp 165-167 °C. IR (Nujol mull): ν 3423,
1
str), 1696 (CdO str) cm-1; H NMR (CDCl3): δ 1.09 (3H, t, J
1
) 7.5 Hz), 1.51 (9H, s), 1.59 (9H, s), 2.33 (3H, s), 2.48 (2H, q,
J ) 7.5 Hz), 4.55 (2H, s), 7.48-7.62 (4H, m), 8.08-8.11 (1H,
3305 (2 × NH str), 1753, 1701, 1660 (3 × CdO str) cm-1; H
NMR (CDCl3): δ 1.41 (9H, s), 2.27 (3H, s), 2.51 (2H, t, J ) 6.9
Hz), 2.77 (2H, t, J ) 6.9 Hz), 3.51 (3H, s), 4.68 (2H, s), 5.41
(2H, s), 7.35-7.42 (5H, m), 7.51-7.55 (2H, m), 7.59-7.61 (2H,
m), 8.18-8.21 (1H, m), 8.50 (1H, br s), 8.56-8.65 (2H, m),
9.79-9.83 (1H, m), 10.05 (1H, br s); 13C NMR (CDCl3): δ 10.5,
19.1, 26.5, 28.3, 51.6, 66.3, 80.6, 113.2, 118.3, 120.1, 120.6,
122.8, 123.0, 123.8, 123.9, 125.4, 126.1, 126.2, 127.0 (2), 127.2,
127.4, 127.5, 128.0, 128.1, 128.2, 128.4, 128.6, 129.6, 130.5,
136.1, 160.1, 160.2, 173.8. Anal. Calcd for C38H38N2O6: C,
74.27; H, 6.07; N, 4.44. Found: C, 74.40; H, 6.12; N, 4.19.
m), 8.54-8.61 (3H, m), 9.29 (1H, br s), 9.73-9.77 (1H, m); 13
C
NMR (CDCl3): δ 10.5, 15.3, 17.4, 27.1, 28.5, 28.7, 80.7, 81.3,
114.6, 117.8, 120.1, 122.9, 123.4, 123.7, 125.1, 125.2, 125.6,
125.7, 126.3, 126.7, 126.9, 127.0, 127.7, 128.5, 128.6, 129.5,
130.3, 159.8, 161.1. Anal. Calcd for C34H38N2O4‚1/2H2O: C,
74.56, H, 6.99; N, 5.11. Found: C, 74.54; H, 7.04; N, 5.05.
Eth yl 3-((5-(Eth oxyca r bon yl)-3-eth yl-4-m eth yl-2-p yr -
r olyl)m et h yl)p h en a n t h r o[9,10-c]p yr r ole-1-ca r b oxyla t e
(17c). Prepared by method A from 14a (0.500 g) and ethyl
5-(acetoxymethyl)-4-ethyl-3-methylpyrrole-2-carboxylate (18c;
0.438 g). Recrystallization from ethanol gave the diethyl ester
17c (0.725 g; 87%) as fluffy pale pink crystals, mp 219 °C
(softens at 210 °C); IR (Nujol mull): ν 3425, 3300 (2 × NH
Ben zyl 3-((3-Eth yl-5-for m yl-4-m eth yl-2-p yr r olyl)m eth -
yl)p h en a n th r o[9,10-c]p yr r ole-1-ca r boxyla te (28a ). Ben-
zyl 3-((5-(tert-butyloxycarbonyl)-3-ethyl-4-methyl-2-pyrrolyl-
)methyl)phenanthro[9,10-c]pyrrole-1-carboxylate (190 mg) was
dissolved in TFA (8 mL) and placed on a warm water bath
(45-50 °C) for 20 min. The solution was diluted with 15 mL
of dichloromethane, washed with water (25 mL), 5% NaHCO3
solution (25 mL), and water (25 mL), and dried over sodium
sulfate. The solvent was evaporated, and the resulting oil was
taken up in 2.0 mL of DMF and placed in a 10 mL round-
bottom flask. The mixture was cooled in an ice/salt bath to 0
°C. Benzoyl chloride (0.19 mL) was added dropwise, main-
taining the temperature of the mixture at 0 °C. After the
addition was completed, the temperature was allowed to drop
to -5 °C, and then the ice/salt bath was removed and stirring
continued at room temperature for 1 h. The flask was then
cooled with an ice/salt bath, 2.0 mL of toluene was added, and
the mixture allowed to stir for an additional 1 h. The
intermediary imine salt oiled out, so the solvents were removed
on a rotary evaporator, initially using a water aspirator and
then at oil pump pressures. The residual oil was taken up in
a 50:50 mixture of ethanol/water (5 mL), sodium carbonate
(190 mg) was added, and the mixture was stirred on a boiling
water bath for 15 min. Water (7 mL) was added, and the
mixture was allowed to stand at room-temperature overnight.
The resulting precipitate was filtered off and recrystallized
from chloroform/petroleum ether to give the monoaldehyde
(100 mg; 60%) as light brown crystals, mp 188 °C, dec; 1H NMR
(CDCl3): δ 1.07 (3H, t, J ) 7.6 Hz), 2.29 (3H, s), 2.47 (2H, q,
J ) 7.6 Hz), 4.58 (2H, s), 5.34 (2H, s), 7.32-7.38 (5H, m), 7.49-
7.62 (4H, m), 7.97-8.01 (1H, m), 8.54-8.61 (2H, m), 8.86 (1H,
br s), 9.50 (1H, s), 9.59 (1H, br s), 9.76-9.79 (1H, m); 13C NMR
(CDCl3): δ 10.5, 18.4, 19.1, 26.2, 28.3, 34.3, 51.5, 51.6, 58.4,
80.5, 113.4, 118.2, 120.0, 120.3, 122.6, 123.0, 123.9, 125.3,
125.9, 126.0, 126.9 (2), 127.0, 127.2, 127.5, 127.7, 128.3, 129.6,
130.4, 160.7, 160.9, 174.0. HR MS (EI): Calcd for
str), 1713, 1653 (2 × CdO str) cm-1
;
1H NMR (d6-DMSO-
CDCl3): δ 0.89 (3H, t, J ) 7.5 Hz), 1.28 (3H, t), 1.43 (3H, t, J
) 7 Hz), 2.21 (3H, s), 2.41 (2H, q, J ) 7.5 Hz), 4.20 (2H, q, J
) 7 Hz), 4.42 (2H, q, J ) 7 Hz), 4.62 (2H, s), 7.44-7.58 (4H,
m), 8.15-8.18 (1H, m), 8.50-8.54 (2H, m), 9.73-9.76 (1H, m),
10.49 (1H, br s), 11.55 (1H, br s); 13C NMR (d6-DMSO-
CDCl3): δ 9.1, 13.3, 14.0, 15.8, 24.7, 58.0, 59.0, 112.2, 116.5,
116.7, 121.9, 122.3, 122.6, 122.8, 123.7, 125.1, 125.6, 126.5,
127.1, 127.4, 127.5, 127.7, 129.0, 159.7, 160.4. Anal. Calcd
for C30H30N2O4: C, 74.67; H, 6.26; N, 5.80. Found: C, 74.57;
H, 6.03; N, 5.75.
Ben zyl 3-((5-(ter t-Bu toxyca r bon yl)-3-eth yl-4-m eth yl-2-
p yr r olyl)m et h yl)p h en a n t h r o[9,10-c]p yr r ole-1-ca r b oxy-
la te (17d ). The title dipyrrylmethane was prepared by
method A from 14e (300 mg) and tert-butyl 5-acetoxymethyl-
4-ethyl-3-methylpyrrole-2-carboxylate43 (18b; 240 mg). Re-
crystallization from carbon tetrachloride gave the dipyrryl-
methane (363 mg; 74%) as pink crystals, mp 193-194 °C, dec
(mp ≈130 °C with rapid heating). Method B similarly gave
the dipyrrylmethane in 85% yield. IR (Nujol mull): ν 3444,
1
3241 (NH str), 1710, 1654 (CdO str) cm-1; H NMR (CDCl3):
δ 1.04 (3H, t, J ) 7.5 Hz), 1.53 (9H, s), 2.32 (3H, s), 2.44 (2H,
q, J ) 7.5 Hz), 4.57 (2H, s), 5.37 (2H, s), 7.36-7.44 (5H, m),
7.52-7.61 (4H, m), 8.09-8.11 (1H, m), 8.57-8.62 (3H, m), 9.45
(1H, br s), 9.79-9.83 (1H, m); 13C NMR (CDCl3): δ 10.6, 15.2,
17.3, 27.1, 28.5, 51.6, 80.7, 113.1, 115.0, 118.0, 120.1, 122.8,
123.0, 123.1, 123.4, 123.5, 123.7, 125.1, 125.2, 125.4, 125.8,
126.0, 126.3, 126.6, 126.8, 127.0 (2), 127.2, 127.4, 128.3, 129.5,
130.5, 160.7, 161.2. Anal. Calcd for C37H36N2O4‚1/2H2O: C,
76.39; H, 6.41; N, 4.81. Found: C, 76.04; H, 6.26; N, 4.74.
ter t-Bu tyl 3-((5-(Ben zyloxyca r bon yl)-3-eth yl-4-m eth yl-
2-p yr r olyl)m eth yl)p h en a n th r o[9,10-c]p yr r ole-1-ca r boxy-
la te (17e). The dipyrrylmethane was prepared by method A
from tert-butyl phenanthro[9,10-c]pyrrole-1-carboxylate (14d ;
1.00 g) and 18a 42 (0.994 g). Recrystallization from carbon
tetrachloride gave the required dipyrrylmethane (1.23 g; 68%)
as pale orange crystals, mp 192-193 °C; IR (Nujol mull): ν
3424 (NH str), 1696 (CdO str) cm-1; 1H NMR (CDCl3): δ 1.08
(3H, t, J ) 7.5 Hz), 1.56 (9H, s), 2.35 (3H, s), 2.46 (2H, q, J )
7.5 Hz), 4.53 (2H, s), 5.20 (2H, s), 7.28 (5H, s), 7.48-7.61 (4H,
m), 8.02-8.05 (1H, m), 8.52-8.57 (2H, m), 8.84 (1H, br s), 9.29
(1H, br s), 9.75 (1H, d, J ) 8.6 Hz); 13C NMR (CDCl3): δ 10.6,
15.3, 17.3, 27.1, 28.4, 65.7, 81.4, 114.7, 117.8, 118.4, 122.9,
123.3, 123.7, 125.1, 125.2, 125.4, 126.7, 126.9, 127.0, 127.7 (2),
128.0 (2), 128.4, 128.5, 129.4, 130.3, 136.2, 159.8, 161.3. Anal.
Calcd for C37H36N2O4‚1/4H2O: C, 76.99; H, 6.37; N, 4.85.
Found: C, 76.92; H, 6.39; N, 4.85.
C
33H28N4O3: m/z 500.20999. Found: 500.21057.
3-((5-(Ben zyloxyca r bon yl)-3-eth yl-4-m eth yl-2-p yr r olyl-
)m eth yl)ph en an th r o[9,10-c]pyr r ole-1-car boxaldeh yde. tert-
Butyl 3-((5-(benzyloxycarbonyl)-3-ethyl-4-methyl-2-pyrrolyl-
)methyl)phenanthro[9,10-c]pyrrole-1-carboxylate (17e; 200 mg)
was taken up in TFA (0.96 mL) and stirred at room temper-
ature for 15 min. The solution was cooled to 0 °C with a salt-
ice bath, and trimethyl orthoformate (0.3 mL) was added
dropwise, maintaining the temperature at 0 °C throughout.
The mixture was stirred at room temperature for 5 min and
poured into 10 mL of water. The resulting precipitate was
suction filtered and recrystallized from chloroform to give the
1
aldehyde (45 mg; 26%) as white crystals, mp 268 °C, dec; H
NMR (CDCl3): δ 1.10 (3H, t, J ) 7.4 Hz), 2.36 (3H, s), 2.45
(2H, q, J ) 7.4 Hz), 4.62 (2H, s), 5.21 (2H, s), 7.32 (5H, m),
7.56-7.66 (4H, m), 8.11-8.15 (1H, m), 8.45-8.49 (1H, m), 8.62
(43) Clezy, P. S.; Crowley, R. J .; Hai, T. T. Aust. J . Chem. 1982, 35,
411.
(44) Clezy, P. S.; Liepa, A. J . Aust. J . Chem. 1970, 23, 2443.

4008 J . Org. Chem., Vol. 63, No. 12, 1998
Novak and Lash
(2H, d, J ) 8 Hz), 8.77 (1H, br s), 9.68 (1H, br s), 10.37 (1H,
s); EI MS: m/z (% rel abund) 500 (100; [M+]). HR MS (EI):
Calcd for C33H28N4O3: m/z 500.20999. Found: 500.20985.
Anal. Calcd for C33H28N2O3: C, 79.18; H, 5.64; N, 5.60.
Found: C, 79.08; H, 5.55; N, 5.59.
1-carboxylate (17a ; 200 mg) was dissolved in 4 mL of TFA and
stirred at room temperature for 15 min. The resulting solution
was diluted with dichloromethane (25 mL), washed with water
(15 mL), 5% sodium bicarbonate solution (15 mL), and water
(15 mL), and dried over sodium sulfate. The solvent was
evaporated under reduced pressure, and the crude residue was
dissolved in dichloromethane (44 mL) and methanol (1.5 mL).
3,3′-Diethyl-4,4′-dimethyl-2,2′-dipyrrylmethane-5,5′-dicarbox-
aldehyde1 (22a ; 101 mg) was added to the mixture, followed
by 400 mg of p-toluenesulfonic acid dissolved in 1.5 mL of
methanol, and the solution was allowed to stir in the dark at
room-temperature overnight. The following day, a saturated
solution of zinc acetate (12 mL) in methanol was added and
the mixture stirred in the dark at room-temperature overnight.
The solvent was evaporated under reduced pressure. The
residue was taken up in a small amount of dichloromethane,
loaded onto a column of grade 3 alumina, and eluted with
dichloromethane. A red fraction was collected, the solvent
evaporated, and the residue taken up in a small amount of
TFA. The mixture was diluted with dichloromethane and
washed with water (15 mL), 5% aqueous sodium bicarbonate
solution (15 mL), and water (15 mL). The solvent was
evaported under reduced pressure, and the residue was
chromatographed on grade 3 alumina, eluting with toluene.
The product fraction was collected as a dark maroon band.
Recrystallization from chloroform/methanol gave the mono-
phenanthroporphyrin (24 mg; 12%) as dark purple crystals,
mp >300 °C.
(b) Benzyl 3-((5-(benzyloxycarbonyl)-3-ethyl-4-methyl-2-pyr-
rolyl)methyl)phenanthro[9,10-c]pyrrole-1-carboxylate (200 mg)
was dissolved in THF (15 mL) in a hydrogenation vessel and
diluted with anhydrous methanol (100 mL). Triethylamine
(10 drops) was added to the mixture, and the vessel was
flushed with nitrogen. Palladium/charcoal (10%; 50 mg) was
cautiously added, and the reaction mixture was shaken under
an atmosphere of hydrogen at 45 psi overnight. The catalyst
was filtered off and the solvent evaporated under reduced
pressure. Residual traces of triethylamine were removed
under high vacuum. The residue was reacted with 22a 1 (90
mg) and p-toluenesulfonic acid (0.394 g) under the conditions
described above. Recrystallization from chloroform/methanol
gave the required porphyrin (54 mg; 29%) as dark purple
crystals, mp > 300 °C; UV-vis (CH2Cl2): λmax (log ꢀ) 417 (5.23),
516 (4.02), 553 (4.47), 577 (4.11), 634 nm (3.58); UV-vis (1%
TFA-CH2Cl2): λmax (log ꢀ) 403 (5.13), 420 (5.17), 566 (4.26),
612 nm (4.26); 1H NMR (CDCl3): δ -4.00 (2H, br s), 1.82-
1.88 (9H, m), 3.50 (3H, s), 3.59 (3H, s), 3.60 (3H, s), 3.93-4.08
(6H, m), 7.83-7.89 (2H, m), 8.00-8.07 (2H, m), 9.05 (2H, d, J
) 8.3 Hz), 9.79-9.88 (4H, m), 10.74 (2H, s); HR MS (FAB):
Calcd for C41H38N4 + H: m/z 587.3166; found 587.3178.
Nickel(II) complex: maroon crystals (chloroform-methanol),
mp > 300 °C; UV-vis (CHCl3): λmax (log ꢀ) 412 (5.13), 534 (3.90),
578 nm (4.47). Copper(II) complex: reddish brown crystals
(chloroform-methanol), mp > 300 °C; UV-vis (CH2Cl2): λmax
(log ꢀ) 414 (5.41), 540 (4.02), 585 nm (4.51). Zinc complex:
purple crystals (chloroform-methanol), mp > 300 °C; UV-vis
(CH2Cl2): λmax (log ꢀ) 418 (5.42), 550 (4.14), 590 nm (4.52).
13,17-Dibu tyl-7-eth yl-8,12,18-tr im eth ylph en an th r o[9,10-
b]p or p h yr in (20). Dibenzyl ester 17b (100 mg) was hydro-
genolyzed as described above in procedure b. The resulting
crude dicarboxylic acid was dissolved with 3,3′-dibutyl-4,4′-
dimethyl-2,2′-dipyrrylmethane-5,5′-dicarboxaldehyde1 (22b; 52
mg) in dichloromethane (180 mL) and methanol (8 mL),
p-toluenesulfonic acid (0.35 g) in methanol (8 mL) was added,
and the resulting mixture was stirred in the dark at room
temperature for 16 h. A saturated solution of zinc acetate in
methanol (8 mL) was added and the solution stirred at room
temperature for a further 24 h. Following the standard
workup (as above), recrystallization from chloroform/methanol
gave the required phenanthroporphyrin (36 mg; 37%) as dark
purple crystals, mp > 300 °C; UV-vis (CH2Cl2): λmax (log ꢀ)
416 (5.24), 512 (4.01), 555 (4.48), 576 (4.12), 633 (3.61) nm; 1H
NMR (CDCl3): δ -3.85 (2H, br s), 1.10-1.17 (6H, m), 1.71-
1.82 (4H, m), 1.89 (3H, t, J ) 7.6 Hz), 2.19-2.31 (4H, m), 3.51
(3H, s), 3.60 (3H, s), 3.62 (3H, s), 3.92 (2H, t, J ) 7.6 Hz), 4.03
Ben zyl 3-((5-F or m yl-3-(2-(m et h oxyca r b on yl)et h yl)-4-
m eth yl-2-p yr r olyl)m eth yl)p h en a n th r o[9,10-c]p yr r ole-1-
ca r boxyla te (28b). The monoaldehyde was prepared by the
method described for 28a from benzyl 3-((5-(tert-butyloxycar-
bonyl)-3-ethyl-4-(2-(methoxycarbonyl)ethyl)-2-pyrrolyl)meth-
yl)phenanthro[9,10-c]pyrrole-1-carboxylate (17f; 191 mg). Re-
crystallization from chloroform/petroleum ether gave the
monoaldehyde (96 mg; 57%) as pale brown crystals, mp 223-
1
224 °C; H NMR (CDCl3): δ 2.26 (3H, s), 2.51 (2H, t, J ) 6.8
Hz), 2.76 (2H, t, J ) 6.8 Hz), 3.53 (3H, s), 4.68 (2H, s), 5.37
(2H, s), 7.32-7.59 (9H, m), 8.03-8.06 (1H, m), 8.54-8.60 (2H,
m), 8.92 (1H, br s), 9.43 (1H, s), 9.75-9.78 (1H, m), 10.17 (1H,
br s); 13C NMR (CDCl3): δ 8.9, 18.9, 26.8, 34,1, 51.8, 66.5,
113.8, 118.8, 121.4, 122.8, 123.1, 123.9, 125.5, 125.8, 126.2,
127.1, 127.3, 127.4, 128.1, 128.4, 128.5, 128.7, 129.0, 129.9,
130.5, 131.4, 133.1, 136.1, 160.2, 173.9, 176.5. Anal. Calcd
for C35H30N2O5‚H2O: C, 72.90; H, 5.59; N, 4.86. Found: C,
73.10; H, 5.58; N, 4.80.
Diben zyl 1,1′-Dip h en a n th r o[9,10-c]p yr r olylm eth a n e-
3,3′-d ica r boxyla te (31c). Benzyl phenanthro[9,10-c]pyrrole-
1-carboxylate (14e; 300 mg), dimethoxymethane (65 mg), and
p-toluenesulfonic acid (30 mg) were dissolved in 30 mL of
glacial acetic acid. The reaction vessel was purged with
nitrogen, and the mixture was stirred under an atmosphere
of nitrogen at room temperature for 3 days. The cloudy
mixture was poured into 300 mL of ice/water and allowed to
stand for 2 h. The resulting precipitate was extracted with
THF, washed with 25 mL of water, 25 mL of 5% sodium
bicarbonate solution, and 25 mL of water, and dried over
sodium sulfate. The solvent was evaporated under reduced
pressure and the residue recrystallized from THF/hexanes to
give the dipyrrylmethane (252 mg; 83%) as pale purple
crystals, mp > 300 °C; IR (Nujol mull): ν 3439 (NH str), 1711
(CdO str) cm-1; 1H NMR (d6-DMSO): δ 5.31 (4H, s), 5.53 (2H,
s), 7.18-7.26 (10H, m), 7.37-7.63 (8H, m), 8.17 (2H, m), 8.66-
8.71 (4H, m), 9.73 (2H, d, J ) 9.2 Hz), 11.81 (2H, br s); 13C
NMR (d6-DMSO): δ 28.8, 51.5, 113.3, 117.7, 123.3, 123.6,
124.4, 125.2, 126.8, 126.9, 127.1, 127.4, 127.7, 128.5, 129.8,
160.9; HR MS (EI): Calcd for C49H34N2O4: m/z 714.2510.
Found: 714.2524.
Diet h yl 1,1′-Dip h en a n t h r o[9,10-c]p yr r olylm et h a n e-
3,3′-d ica r boxyla te (31a ). The dipyrrylmethane was prepared
by the procedure given for 31c from ethyl phenanthro[9,10-
c]pyrrole-1-carboxylate (14a ; 500 mg), dimethoxymethane (132
mg), and p-toluenesulfonic acid (50 mg). Recrystallization
from toluene gave the dipyrrylmethane (343 mg; 67%) as off-
white crystals, mp > 300 °C; IR (Nujol mull): ν 3395 (NH str),
1704, 1638 (CdO str) cm-1; 1H NMR (d8-THF): δ 1.08 (6H, t,
J ) 7 Hz), 4.19 (4H, q, J ) 7 Hz), 5.47 (2H, s), 7.45-7.59 (8H,
m), 8.24-8.26 (2H, m), 8.64-8.70 (4H, m), 9.90-9.94 (2H, m),
10.86 (2H, br s); HR MS (EI): Calcd for C39H30N2O4: m/z
590.2198. Found: 590.2200. Anal. Calcd for C39H30N2O4‚
1/2H2O: C, 78.11; H, 5.21; N, 4.67. Found: C, 77.87; H, 4.89;
N, 4.45.
Dim eth yl 1,1′-Dip h en a n th r o[9,10-c]p yr r olylm eth a n e-
3,3′-d ica r boxyla te (31b). The dipyrrylmethane was pre-
pared from methyl phenanthro[9,10-c]pyrrole-1-carboxylate
(14c; 500 mg) by the procedure given for 31c. Recrystallization
from toluene gave the dipyrrylmethane (423 mg; 83%) as off-
white crystals, mp 283 °C, dec; IR (Nujol mull): ν 3409 (NH
str), 1713, 1645 (CdO str) cm-1 1H NMR (d8-THF): δ 3.75
;
(6H, s), 5.45 (2H, s), 7.40-7.58 (8H, m), 8.20-8.23 (2H, m),
8.64-8.70 (4H, m), 9.92-9.96 (2H, m), 10.93 (2H, br s); 13C
NMR (d8-THF): δ 30.6, 51.7, 115.4, 119.6, 124.1, 124.6, 124.8,
126.2, 126.6, 126.8, 127.8, 128.3, 129.0, 129.6, 129.7, 130.8,
131.8, 161.7. Anal. Calcd for C37H26N2O4‚3/5H2O: C, 77.50;
H, 4.78; N, 4.88. Found: C, 77.28; H, 4.35; N, 4.84.
7,13,17-Tr ie t h yl-8,12,18-t r im e t h ylp h e n a n t h r o[9,10-
b]p or p h yr in (19). (a) tert-Butyl 3-((5-(tert-butoxycarbonyl)-
3-ethyl-4-methyl-2-pyrrolyl)methyl)phenanthro[9,10-c]pyrrole-

Porphyrins with Exocyclic Rings
J . Org. Chem., Vol. 63, No. 12, 1998 4009
(2H, t, J ) 7.5 Hz), 4.10 (2H, q, J ) 7.6 Hz), 7.89 (2H, t), 8.05-
8.09 (2H, m), 9.08 (2H, d, J ) 8.3 Hz), 9.87-9.91 (4H, m), 10.83
(1H, s), 10.85 (1H, s); HR MS (FAB): Calcd for C45H46N4 + H:
m/z 643.3790. Found: 643.3800.
mL) was added to the mixture and stirring was continued
overnight. The mixture was washed with water, the solvent
evaporated under reduced pressure, and the residue dissolved
in a small amount of TFA to demetalate the zinc chelate and
diluted with dichloromethane, washed with water, 5% aqueous
sodium bicarbonate solution, and water. The solvent was
evaporated under reduced pressure and the residue chromato-
graphed on grade 3 alumina eluting initially with dichlo-
romethane and then chloroform. The deep olive-green solu-
tions were recolumned on grade 3 alumina, eluting initially
with toluene. After a porphyrin byproduct had eluted, the
eluent was switched to 5% ethyl acetate/toluene and an olive-
green band was collected. Recrystallization from chloroform/
methanol gave the diphenanthroporphyrin (65 mg; 18%) as a
dark maroon powder, mp > 300 °C; UV-vis (CH2Cl2): λmax (log
ꢀ) 434 (5.26), 538 (4.15), 571 (4.46), 593 (4.08), 651 (4.16) nm;
UV-vis (1% TFA-CH2Cl2): λmax (log ꢀ) 448 (5.27), 583 (4.32),
632 (4.50) nm; 1H NMR (TFA-CDCl3): δ -2.57 (2H, br s),
-2.16 (2H, br s), 1.08 (6H, t, J ) 7.3 Hz), 1.67 (4H, sextet),
2.11 (4H, pentet), 3.65 (6H, s), 4.04 (4H, t, J ) 7.6 Hz), 8.13-
8.26 (6H, m), 8.33 (2H, t), 9.27 (4H, d, J ) 8.1 Hz), 9.73 (2H,
d, J ) 8.1 Hz), 9.96 (2H, d, J ) 8.1 Hz), 10.47 (1H, s), 11.39
(2H, s), 12.32 (1H, s); 13C NMR (TFA-CDCl3): δ 12.0, 13.7,
23.1, 26.6, 34.2, 98.2, 100.1, 102.1, 125.3, 127.3 (2), 127.5,
127.8, 129.6, 129.8, 129.9, 130.4, 133.7, 133.9, 138.5, 138.6,
143.3, 143.5; HR MS (FAB): Calcd for C54H46N4 + H: m/z
751.3790. Found: 751.3813. Nickel(II) complex: dark green
7,17-Diet h yl-8,18-d im et h yld ip h en a n t h r o[9,10-b:9,10-
l]p or p h yr in (27a ). Benzyl 3-((5-formyl-3-ethyl-4-methyl-2-
pyrrolyl)methyl)phenanthro[9,10-c]pyrrole-1-carboxylate (27a ;
100 mg) was placed in a hydrogenation vessel and dissolved
in anhydrous THF (15 mL) and methanol (100 mL). Triethy-
lamine (10 drops) was added to the mixture, and the vessel
was flushed with nitrogen. Palladium/charcoal (10%; 50 mg)
was added to the mixture, and the reaction vessel was shaken
under an atmosphere of hydrogen at 45 psi overnight. The
catalyst was filtered off and the solvent removed under reduced
pressure. Residual traces of triethylamine were removed
under high vacuum. The crude dipyrrylmethane was taken
up in dichloromethane (22 mL) and methanol (0.75 mL).
p-Toluenesulfonic acid (200 mg) in methanol (0.75 mL) was
added, and the mixture was stirred in the dark at room-
temperature overnight. A saturated solution of zinc acetate
in methanol (3.5 mL) was added and the mixture stirred for
an additional 24 h. The solvent was then evaporated under
reduced pressure and the residue dissolved in a small amount
of TFA. The solution was diluted with 25 mL of dichlo-
romethane and washed with water (15 mL), 5% NaHCO3
solution (15 mL), and water (15 mL). Recrystallization from
chloroform/methanol gave the diphenanthroporphyrin (19 mg;
27%) as purple crystals, mp > 300 °C; UV-vis (1% TFA-
CH2Cl2): λmax (log ꢀ) 436 (5.11), 458 (5.14), 581 (4.12), 638 (4.60)
nm; 1H NMR (TFA-CDCl3): δ -2.91 (2H, br s), -1.39 (2H, br
s), 1.69 (6H, t, J ) 6.7 Hz), 3.61 (6H, s), 4.10 (4H, q, J ) 6.7
Hz), 8.17 (4H, m), 8.35 (4H, m), 9.26 (4H, d, J ) 6.8 Hz), 9.91
(4H, m), 11.32 (4H, s); HR MS (FAB): calcd for C50H38N4 + H:
m/z 695.3166; found: 695.3165.
powder (chloroform-methanol), mp
> 300 °C; UV-vis
(CHCl3): λmax (log ꢀ) 429 (5.19), 551 (4.03), 594 (4.62) nm.
Copper(II) complex: green crystals (chloroform-methanol), mp
> 300 °C; UV-vis (5% pyrrolidine-CHCl3): λmax (relative ratios)
432 (1), 557 (0.064), 599 nm (0.198). Zinc complex: bright
green crystals (chloroform-methanol), mp > 300 °C; UV-vis
(trace pyrrolidine-CHCl3): λmax (log ꢀ) 428 (4.27), 453 (5.02),
573 (3.86), 614 (4.12) nm.
7,17-Bis(2-(m e t h oxyca r b on yl)e t h yl)-8,18-d im e t h yl-
d ip h en a n th r o[9,10-b:9,10-l] p or p h yr in (27b). The title
porphyrin was prepared by the procedure given for 27a from
benzyl 3-((5-formyl-3-(2-(methoxycarbonyl)ethyl)-4-methyl-2-
pyrrolyl)methyl)phenanthro[9,10-c]pyrrole-1-carboxylate (96
mg). Following the demetalation step, the crude product was
reesterified with 5% H2SO4-methanol at room-temperature
overnight. The porphyrin was purified by chromatography on
grade 3 alumina, eluting with dichloromethane. Recrystalli-
zation from chloroform/methanol gave the diphenanthropor-
phyrin (22 mg; 31%) as purple crystals, mp > 300 °C; UV-vis
(CH2Cl2): λmax (log ꢀ) 428 (5.24), 568 (4.57), 591 (4.37), 645
(3.63) nm; UV-vis (1% TFA-CH2Cl2): λmax (log ꢀ) 438 (5.12),
T e t r a p h e n a n t h r o [9,10-b :9,10-g :9,10-l :9,10-q ]p o r -
p h yr in (10). A solution of ethyl phenanthro[9,10-c]pyrrole-
1-carboxylate (500 mg) in THF (50 mL) was added dropwise
over a period of 20-30 min to a stirred mixture of lithium
aluminum hydride (130 mg) in THF (50 mL), maintaining the
temperature of the mixture at 0 °C with the aid of a salt/ice
bath. The mixture was stirred for an additional 1 h, water
was added, and the organic phase was separated. The aqueous
layer was extracted with chloroform (2 × 50 mL), and the
combined organic solutions were washed with water (50 mL)
and dried over sodium sulfate. The solvent was evaporated
under reduced pressure, maintaining the temperature of the
water bath at 25-30 °C. The residual oil was taken up in
chloroform (125 mL), the air was purged with nitrogen, and
60 µL of a 2.5 M boron trifluoride etherate solution in
dichloromethane was added. The resulting pale blue mixture
was stirred in the dark at room temperature for 1 h. DDQ
(290 mg) was added in a single portion, and stirring was
continued for an additional 1 h. The mixture was washed with
water (50 mL), 5% NaHCO3 solution (50 mL), and water (50
mL), and the solvent was evaporated under reduced pressure.
Recrystallization twice from chloroform/methanol gave the
tetraphenanthroporphyrin (52 mg; 13%) as a dark green
powder, mp > 400 °C; UV-vis (1%TFA-CHCl3): λmax (log ꢀ)
1
459 (5.12), 583 (4.20), 635 (4.57) nm; H NMR (TFA-CDCl3):
δ -2.98 (2H, br s), -1.39 (2H, br s), 3.14 (4H, t, J ) 7.4 Hz),
3.63 (6H, s), 3.70 (6H, s), 4.40 (4H, t, J ) 7.4 Hz), 8.19 (4H, t,
J ) 8.3 Hz), 8.34 (4H, q, J ) 8.3 Hz), 9.28 (4H, d, J ) 8.3 Hz),
9.89 (2H, d, J ) 8.3 Hz), 10.05 (2H, d, J ) 8.3 Hz), 11.33 (2H,
s), 11.51 (2H, s); HR MS (FAB): calcd for C54H42N4O4 + H:
m/z 811.3274; found: 811.3271. Dibutyl ester: purple crystals
(chloroform-methanol), mp 282 °C; UV-vis (CHCl3): λmax (log
ꢀ) 409 (infl; 5.07), 429 (5.30), 550 (infl; 4.04), 573 (4.69), 591
(4.10), 647 nm (3.12). Zinc complex: green flakes (chloroform-
methanol), mp > 300 °C; UV-vis (CHCl3): λmax (log ꢀ) 440
(5.49), 565 (4.08), 614 nm (4.76).
13,17-Dibu tyl-12,18-d im eth yld ip h en a n th r o[9,10-b:9,10-
g]p or p h yr in (30). Diethyl 1,1′-diphenanthro[9,10-c]pyrro-
lylmethane-3,3′-dicarboxylate (31a ; 294 mg) and potassium
hydroxide (300 mg) were dissolved in ethylene glycol (30 mL).
Nitrogen was allowed to bubble through the mixture for 5-10
min before placing the reaction flask in a preheated oil bath
(190-200 °C). The mixture was heated under reflux under
an atmosphere of nitrogen for 25 min. The reaction mixture
was cooled and diluted with chloroform, washed with water
(25 mL), and dried over sodium sulfate. The solvent was
evaporated under reduced pressure and the residue taken up
in 550 mL of dichloromethane and 25 mL of methanol.
Dialdehyde 22b1 (160 mg) and p-toluenesulfonic acid (596 mg)
in methanol (25 mL) were added to the mixture, and the
solution was stirred in the dark at room temperature over-
night. A saturated solution of zinc acetate in methanol (20
1
482 (5.35), 615 (4.26), 668 (4.63) nm; H NMR (TFA-CDCl3):
δ - 0.55 (4H, br s), 8.13 (8H, t), 8.24 (8H, t), 9.24 (8H, d, 8.3
Hz), 9.71 (8H, d, J ) 8.2 Hz), 12.01 (4H, s); 13C NMR (TFA-
CDCl3): δ 101.4 (meso-CH), 125.1, 126.9, 127.3, 129.6, 129.7,
129.8, 133.8, 139.5; HRMS (FAB): calculated for C68H38N4
+
H: m/z 911.3175; found: 911.3168. Anal. Calcd for C68H36N4‚
2H2O: C, 86.23; H, 4.47; N, 5.92. Found: C, 86.15; H, 4.42;
N, 5.93.
Ack n ow led gm en t. This material is based upon
work supported by the National Science Foundation
under Grant Nos. CHE-9201149 and CHE-9500630, and
the University Research Fund of Illinois State Univer-
sity.

4010 J . Org. Chem., Vol. 63, No. 12, 1998
Novak and Lash
Su p p or tin g In for m a tion Ava ila ble: Copies of UV-vis
spectra for porphyrins 10, 19, 20, 27 and 30, and 1H and 13C
NMR spectra for compounds 10, 12, 14, 16, 17, 19, 20, 27, 28,
30, and 31 (54 pages). This material is contained in libraries
on microfiche, immediately follows this article in the microfilm
version of the journal, and can be ordered from the ACS; see
any current masthead page for ordering information.
J O980043M